Etching solution for silicon nitride, method for processing substrates, method for manufacturing semiconductor devices, silicon etching inhibitor

Abstract

This invention provides an etching solution for silicon nitrides that can efficiently etch silicon nitrides. [Solution] An etching solution for silicon nitride comprising one or more acids selected from the group consisting of sulfuric acid and organic acids that do not contain aromatic rings (component A), a boron compound (component B), a silicon compound (component C) having at least one Si-O bond and one Si-C bond, and water.

Description

Technical Field

[0001] The present invention relates to an etching solution for silicon nitride, a method for treating a substrate, a method for manufacturing a semiconductor device, and a silicon etching inhibitor.

Background Art

[0002] In the semiconductor field, materials such as silicon or silicon oxide are widely used as materials for semiconductor devices. In the manufacture of semiconductor devices, etching technology is used to accurately design complex circuits, and the desired material can be processed into an arbitrary shape by this technology. In the manufacture of semiconductor devices containing silicon, for example, after forming a laminate of a film such as silicon or silicon oxide and a film made of another material, an etching process is performed to remove part or all of the film made of another material.

[0003] As an etching solution capable of efficiently etching silicon nitride, Patent Document 1 proposes an etching solution containing water, sulfuric acid, and a boron compound.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] While efforts have been made to develop technologies for efficiently removing silicon nitride material from materials such as silicon or silicon oxide, these methods are not yet sufficient, and further improvements in efficiency are expected. Therefore, the first objective of the present invention is to provide an etching solution for silicon nitride that can efficiently etch silicon nitride. Furthermore, a second objective of the present invention is to provide an etching inhibitor that can efficiently suppress the etching of materials such as silicon or silicon oxide. [Means for solving the problem]

[0006] In view of the above problems, the inventors conducted diligent research. As a result, they found that the first problem can be solved by including one or more acids selected from the group consisting of sulfuric acid and organic acids that do not contain aromatic rings, a boron compound, and water, in addition to a silicon compound having a specific structure. Furthermore, they found that the second problem can be solved by an organosilicon compound having a specific structure.

[0007] In other words, the gist of this disclosure is as follows: Item 1. An etching solution for silicon nitride comprising one or more acids selected from the group consisting of sulfuric acid and organic acids that do not contain aromatic rings (component A), a boron compound (component B), a silicon compound having at least one Si-O bond and one Si-C bond (component C), and water. Item 2. The silico described in Item 1, wherein the pKa of the acid at 25°C is between -5 and 2. Etching solution for nitrides. Item 3. The silicon nitride etching solution according to Item 1 or 2, wherein at least one of the boiling point and decomposition temperature of the acid at 1 atmosphere is 150°C or higher and 400°C or lower. Item 4. The etching solution for silicon nitride according to any one of items 1 to 3, wherein the aromatic ring-free organic acid is one or more aromatic ring-free organic acids selected from sulfonic acid compounds and carboxylic acid compounds. Item 5. An etching solution for silicon nitride according to any one of Items 1 to 4, further comprising an aromatic ring compound having an electron-withdrawing group (Component G). Item 6. The etching solution for silicon nitride according to any one of Items 1 to 5, wherein the organosilicon compound (Component C) is represented by any one of the following formulas (1) to (3). [Chemical formula] (In the above formulas (1) to (3), R 1 ~R 3 each independently represents a hydrogen atom, an aryl group having 5 to 12 carbon atoms which may have a substituent, a linear alkenyl group having 2 to 10 carbon atoms which may have a substituent, a branched alkenyl group having 3 to 10 carbon atoms which may have a substituent, a linear alkynyl group having 2 to 10 carbon atoms which may have a substituent, a linear alkoxy group having 2 to 10 carbon atoms which may have a substituent, an epoxy group, a styryl group, a methacyloxy group, an acyloxy group, an amino group, a ureido group, an isocyanate group, an isocyanurate group, or a mercapto group; one or more of 1 ~R 3 each independently has a hydrophobic group capable of forming a Si-C bond with Si represented in formula (1); 4 R represents a hydrogen atom, an aryl group having 5 to 12 carbon atoms which may have a substituent, a linear alkenyl group having 2 to 10 carbon atoms which may have a substituent, a branched alkenyl group having 3 to 10 carbon atoms which may have a substituent, a linear alkynyl group having 2 to 10 carbon atoms which may have a substituent, an epoxy group, a styryl group, a methacyloxy group, an acyloxy group, an amino group, a ureido group, an isocyanate group, an isocyanurate group, or a mercapto group; 11 R 16 and 21 ~R 26Each of these independently comprises a hydrogen atom, a C1-C10 linear alkyl group which may have substituents, a C3-C10 branched alkyl group which may have substituents, a C3-C10 cyclic alkyl group which may have substituents, an aryl group which may have substituents, a C5-C12 linear alkenyl group which may have substituents, a C2-C10 linear alkenyl group which may have substituents, a C3-C10 branched alkenyl group which may have substituents, a C2-C10 linear alkynyl group which may have substituents, and even if substituents are present. R represents a linear alkoxy group, epoxy group, styryl group, metasyloxy group, acyloxy group, amino group, ureido group, isocyanate group, isocyanurate group, or mercapto group having 2 to 10 carbon atoms; 11 ~R 16 One or more of these independently have a hydrophobic group capable of forming a Si-C bond with the Si represented in formula (2); R 21 ~R 26 One or more of these independently have a hydrophobic group capable of forming a Si-C bond with the Si represented in formula (3); n 11 n is an integer between 1 and 10; 21 (This is an integer between 1 and 10.) Item 7. An etching solution for silicon nitride according to any one of items 1 to 6, wherein the total concentration of the organosilicon compounds is 0.1 ppm by mass or more and less than 1,000 ppm by mass. Item 8. A method for processing a substrate containing silicon nitride, A method for processing a substrate, comprising an etching step of etching a silicon nitride using a silicon nitride etching solution described in any one of items 1 to 7. Item 9. The substrate further comprises at least one selected from the group consisting of silicon and silicon oxide. The substrate processing method according to item 8, wherein the etching step is a step of selectively etching a silicon nitride with at least one selected from the group consisting of silicon and silicon oxide using the etching solution. Item 10. A method for manufacturing a semiconductor device using a substrate containing silicon nitride, A method for manufacturing a semiconductor device, comprising an etching step of etching a silicon nitride using a silicon nitride etching solution described in any one of items 1 to 7. Item 11. The substrate further comprises at least one selected from the group consisting of silicon and silicon oxide. The method for manufacturing a semiconductor device according to claim 10, wherein the etching step is a step of selectively etching a silicon nitride with at least one selected from the group consisting of silicon and silicon oxide using the etching solution. Item 12. A silicon etching inhibitor comprising an organosilicon compound having at least one Si-O bond and at least one Si-C bond. Item 13. A silicon etching inhibitor comprising an organosilicon compound having a structure represented by any of the following formulas (1) to (3). [ka] (In equations (1) to (3) above, R 1 ~R 3 Each of these independently comprises a hydrogen atom and a carbon atom having 5 to 12 carbon atoms, which may have substituents. R represents an aryl group, a linear alkenyl group having 2 to 10 carbon atoms which may have substituents, a branched alkenyl group having 3 to 10 carbon atoms which may have substituents, a linear alkynyl group having 2 to 10 carbon atoms which may have substituents, a linear alkoxy group having 2 to 10 carbon atoms which may have substituents, an epoxy group, a styryl group, a metasyloxy group, an acyloxy group, an amino group, a ureido group, an isocyanate group, an isocyanurate group, or a mercapto group; 1 ~R 3 One or more of these independently have a hydrophobic group capable of forming a Si-C bond with the Si represented in formula (1); R 4This represents a hydrogen atom, an optionally substituted aryl group having 5 to 12 carbon atoms, an optionally substituted linear alkenyl group having 2 to 10 carbon atoms, an optionally substituted branched alkenyl group having 3 to 10 carbon atoms, an optionally substituted linear alkynyl group having 2 to 10 carbon atoms, an epoxy group, a styryl group, a metasyloxy group, an acyloxy group, an amino group, a ureido group, an isocyanate group, an isocyanurate group, or a mercapto group; R 11 ~R 16 and R 21 ~R 26 Each independently represents a hydrogen atom, a C1-C10 linear alkyl group which may have substituents, a C3-C10 branched alkyl group which may have substituents, a C3-C10 cyclic alkyl group which may have substituents, an aryl group which may have substituents, a C5-C12 linear alkenyl group which may have substituents, a C2-C10 linear alkenyl group which may have substituents, a C3-C10 branched alkenyl group which may have substituents, a C2-C10 linear alkynyl group which may have substituents, a C2-C10 linear alkoxy group which may have substituents, an epoxy group, a styryl group, a metasyloxy group, an acyloxy group, an amino group, a ureido group, an isocyanate group, an isocyanurate group, or a mercapto group; R 11 ~R 16 One or more of these independently have a hydrophobic group capable of forming a Si-C bond with the Si represented in formula (2); R 21 ~R 26 One or more of these independently have a hydrophobic group capable of forming a Si-C bond with the Si represented in formula (3); n 11 n is an integer between 1 and 10; 21 (This is an integer between 1 and 10.) Item 14. A method for producing an etching solution for silicon nitride, comprising a mixing step of mixing one or more acids selected from the group consisting of sulfuric acid and organic acids that do not contain aromatic rings (component A), a boron compound (component B), a silicon compound having at least one Si-O bond and one Si-C bond (component C), and water to obtain a mixture. Item 15. A method for producing an etching solution for silicon nitride according to Item 14, wherein the total concentration of component C in the mixture is 0.1 ppm by mass or more and less than 1,000 ppm by mass. Item 16. A method for producing a silicon nitride etching solution according to item 14 or 15, further comprising a heat treatment of heating the mixture to 80-200°C. [Effects of the Invention]

[0008] According to a first aspect of the present invention, an etching solution for silicon nitrides that can efficiently etch silicon nitrides can be provided. Furthermore, according to a second aspect of the present invention, an etching inhibitor that can efficiently suppress the etching of materials such as silicon or silicon oxides can be provided. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described in detail below, but the present invention is not limited to these contents unless it exceeds the spirit of the invention. Furthermore, the present invention can be modified and implemented as desired without departing from its spirit.

[0010] In this specification, a numerical range indicated by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively, and "A~B" means that it is greater than or equal to A and less than or equal to B. Furthermore, when a numerical range is described in steps, the upper and lower limits of each numerical range can be combined in any way. Furthermore, in this specification, the expression "A or B" means "selected from the group consisting of A and B". This can be rephrased as "at least one." Furthermore, although this specification describes multiple embodiments, various conditions in each embodiment can be applied to each other to the extent applicable. Furthermore, in this specification, the expression "etching selectivity ratio of B to A" refers to "the ratio of the etching rate that removes B to the etching rate that removes A" (etching rate that removes B / etching rate that removes A). Furthermore, in this specification, "concentration" refers to the content (proportion) of each component in a solution at 25°C. Therefore, "concentration" can express not only the content of solute in the solution, but also the content of solvents such as water in the solution. Furthermore, in this specification, "efficient etching" means a fast etching rate unless otherwise specified.

[0011] <Silicon Etching Solution> An etching solution according to one embodiment of the present invention is an etching solution for efficiently removing (etching) silicon nitride (SiN), and specifically comprises one or more acids selected from the group consisting of sulfuric acid and organic acids that do not contain aromatic rings (component A), a boron compound (component B), a silicon compound having at least one Si-O bond and one Si-C bond (component C), and water, and is an etching solution for silicon nitride (first embodiment of the present invention; also simply referred to as "etching solution" or "silicon nitride etching solution"). Therefore, it can be used for etching silicon nitride in the manufacture of semiconductor devices, etc.

[0012] The silicon compound (component C) having at least one Si-O bond and one Si-C bond is a silicon compound having one or more silanol groups (Si-OH), or a silicon compound that can be hydrolyzed in a strong acid to produce a silicon compound having one or more silanol groups, such as silicic acid. The applicant speculates that these silanol groups condense with the hydroxyl groups on the silicon surface, and the silicon compound hydrophobicly covers the silicon surface, thereby making the silicon surface less susceptible to nucleophilic attack and suppressing silicon etching.

[0013] [Specific acid (component A)] The etching solution contains one or more acids (component A) selected from the group consisting of sulfuric acid and organic acids that do not contain aromatic rings. As the specific acid, sulfuric acid may be used alone, an organic acid that does not contain aromatic rings may be used alone, or both may be used in combination. Furthermore, sulfuric acid and organic acids that do not contain aromatic rings may exist in the etching solution as free substances or as salts with basic compounds. However, from the viewpoint of effectively raising at least one of the boiling point and decomposition temperature of the etching solution (hereinafter also referred to as "boiling point, etc."), it is preferable that they exist as free substances. A specific acid may be used alone, or two or more may be used in combination. Furthermore, there are no particular restrictions on the method of producing the specific acid; it may be synthesized by known methods or a commercially available product may be used. Furthermore, the term "aromatic ring" in a specific acid includes both aromatic rings and heteroaromatic rings.

[0014] Furthermore, from the viewpoint of selectively etching silicon nitrides with respect to silicon, organic acids that do not contain aromatic rings are preferably used. The inventors of the present invention speculate as follows on why selective etching of silicon nitrides is possible when sulfuric acid and organic acids that do not contain aromatic rings are used.

[0015] Although the surface of hydrogen-terminated silicon is hydrophobic, the surfaces of hydroxyl-terminated silicon and silicon oxides formed during the silicon etching process are hydrophilic. Therefore, water can easily approach these surfaces, and etching due to nucleophilic substitution reactions between silicon atoms and water proceeds easily. However, if an organic acid without aromatic rings is included as the specific acid, it is presumed that a dehydration condensation reaction occurs between the hydroxyl groups on the surface of silicon, etc., and the organic acid without aromatic rings. In this case, the hydrophobic groups of the organic acid without aromatic rings are directed outward (towards the liquid phase), making the surface of silicon, etc., hydrophobic. Therefore, water has difficulty approaching the surface of silicon, etc., and etching of silicon, etc., becomes less likely to proceed. Furthermore, when an etching inhibitor for silicon, etc. is added separately, using an organic acid without aromatic rings as the specific acid makes the substrate surface hydrophobic, so it can be expected that the etching inhibitor will be more easily adsorbed. On the other hand, although hydroxyl-terminated silicon on the surface of silicon nitride also undergoes a dehydration condensation reaction with organic acids without aromatic rings, the silicon nitride maintains its hydrophilicity due to the presence of nitrogen sites on the surface. That is, under strongly acidic conditions, the nitrogen sites are protonated and become cations, so hydrophilicity is high, and it is presumed that hydrophilicity can be maintained even when organic acids without aromatic rings are bonded to silicon sites. Furthermore, since the silicon atom density on the silicon nitride surface is lower than that on the silicon surface, the density of organic acids that do not contain bonded aromatic rings is also low, resulting in less steric hindrance. Therefore, it is presumed that the approach of nucleophiles such as water is not easily inhibited. Consequently, when organic acids that do not contain aromatic rings are included as specific acids, the etching of silicon and other materials is selectively suppressed compared to the etching of silicon nitride, allowing for selective etching of silicon nitride with respect to silicon and other materials.

[0016] Furthermore, when sulfuric acid is included as a specific acid, it adsorbs onto the surface of silicon or silicon oxide, causing the surface charge of each to become negatively charged. This makes it easier for organosilicon compounds to adsorb, and etching can be efficiently suppressed.

[0017] Etching of silicon nitride proceeds through the protonation of nitrogen sites in the silicon nitride, followed by nucleophilic attack of water or hydroxide ions on silicon sites. Therefore, if the pH of the etching solution is too high (i.e., if the concentration of a specific acid is too low), the rate of protonation of nitrogen sites decreases significantly, and the etching rate of silicon nitride tends to decrease. Also, if the pH of the etching solution is too high (i.e., if the concentration of a specific acid is too low), the boiling point of the etching solution decreases, making it difficult to control the temperature conditions. Note that etching of silicon and similar materials proceeds solely by nucleophilic attack of water or hydroxide ions, so the etching rate tends to increase when the pH of the etching solution is high.

[0018] Therefore, the pH of the etching solution diluted 10 times by mass with water at 24°C is 5.0 or less (0.0 to 5.0). More preferably, the pH is greater than 0.0 and 4.0 or less, even more preferably greater than 0.1 and 3.0 or less, particularly preferably greater than 0.1 and 2.0 or less, and most preferably 0.1 to 1.0 or less. pH refers to the value measured by the glass electrode method described later. The reason for diluting the etching solution 10 times is to avoid unstable pH measurement due to high concentrations of components other than water in the etching solution. Furthermore, there are no particular restrictions on the size of the object to be measured for pH. The entire amount of the manufactured or sold etching solution may be diluted 10 times with water, or a portion of the etching solution (for example, 10 g or 10% by mass of the etching solution) may be taken out and diluted 10 times with water.

[0019] Because the pH of the etching solution is within the above range, the protonation of the nitrogen sites of silicon nitride proceeds sufficiently quickly, allowing for efficient etching of silicon nitride. Furthermore, in terms of adjusting the boiling point and pH of the etching solution, the total concentration of one or more acids selected from the group consisting of sulfuric acid and organic acids that do not contain aromatic rings in the etching solution is preferably 60% by mass or more and 95% by mass or less, and more preferably 60% by mass or more and 90% by mass or less. More preferably 65% ​​by mass or more and 90% by mass or less, particularly preferably 70% by mass or more and 90% by mass or less, and especially particularly preferably 70% by mass or more and 85% by mass or less.

[0020] The pKa of the specific acid is not particularly limited, but it is preferably -5 or higher and 2 or lower at 25°C, more preferably -5 or higher and 1 or lower, even more preferably -5 or higher and 0 or lower, and particularly preferably -5 or higher and -1 or lower. If the above pKa is above the lower limit of the above range, the decrease in the etching rate of silicon nitride caused by the polymerization of silicic acid, which is an etching product of each silicon compound, can be suppressed. Furthermore, if the pKa is below the upper limit of the above range, dehydration condensation with hydroxyl groups on the hydroxyl-terminated silicon surface or silicon oxide surface is easily performed, and etching of silicon and the like can be efficiently suppressed. It is also preferable that the pKa of the specific acid is low, as it allows the boiling point of the etching solution to be raised at a lower concentration of the specific acid. Furthermore, if the specific acid is a polyhydric acid, the specific acid will have multiple pKa levels, but it is preferable that the pKa level of any one of these levels satisfies the above range, and it is more preferable that the lowest first pKa satisfies the above range.

[0021] The boiling point of the specific acid (NBP, boiling point at 1 atmosphere, etc.) is not particularly limited, but even when etching is performed while heating the etching solution for a long period of time, it is preferable that the boiling point be 150°C or higher, more preferably 200°C or higher, even more preferably 250°C or higher, and particularly preferably 300°C or higher, from the viewpoint of suppressing changes in the concentration of the specific acid due to the volatilization of the specific acid. On the other hand, there is no particular upper limit to the boiling point, etc., and it may be 400°C or lower, or 350°C or lower.

[0022] (sulfuric acid) The etching solution may contain sulfuric acid as a specific acid. The presence of sulfuric acid generates hydrogen ions, which can be used to adjust the pH of the etching solution. Furthermore, sulfuric acid has a very low pKa of -3 at 25°C and possesses two hydroxyl groups, resulting in strong interaction with water. In other words, the presence of sulfuric acid makes it easier to suppress the boiling of water and thus raise the boiling point of the etching solution.

[0023] The form of sulfuric acid is not particularly limited, but as will be described later, it is preferable for the etching solution to have a low concentration of metal. Therefore, it is preferable to use sulfuric acid that contains as few metal impurities and insoluble impurities as possible, and commercially available products can be purified and used as needed. In addition, commercially available high-purity sulfuric acid aqueous solutions for the electronics industry can also be used, and when manufacturing the etching solution, this solution can be mixed directly with water and other components.

[0024] Furthermore, from the viewpoint of suppressing the boiling of water in the etching solution when the etching solution is heated, and from the viewpoint of preventing phosphorus residue on the surface of the treated substrate when phosphoric acid is used as the etching agent (it is known that phosphorus tends to remain on the surface of the treated substrate when phosphoric acid is used and is difficult to remove. Also, since phosphorus is an n-type dopant of silicon, its residue is undesirable), sulfuric acid is preferred as the inorganic acid. However, if this limitation is removed, inorganic acids other than sulfuric acid can also be used, for example, phosphoric acid or other sulfonic acids can be used.

[0025] (Organic acids that do not contain aromatic rings) The etching solution may contain an organic acid that does not contain an aromatic ring as a specific acid. Similar to sulfuric acid, the inclusion of an organic acid that does not contain an aromatic ring generates hydrogen ions, which can be used to adjust the pH of the etching solution. In this specification, organic acids that do not contain aromatic rings do not contain boron compounds.

[0026] The form of the organic acid that does not contain an aromatic ring is not particularly limited, for example, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, isobutanoic acid, isopentanoic acid, isohexanoic acid, isoheptanoic acid, isooctanoic acid, 2-cyclobutylacetic acid, cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, tridecanediic acid, methylsuccinic acid, tetramethylsuccinic acid, benzoic acid, nitrobenzoic acid carboxylic acid compounds such as dinitrobenzoic acid, chloronitrobenzoic acid, chlorodinitrobenzoic acid, phthalic acid, chlorophthalic acid, nitrophthalic acid, terephthalic acid, chloroterephthalic acid, or nitroterephthalic acid (the listed aromatic carboxylic acid compounds include their respective isomers); methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, butanesulfonic acid, pentanesulfonic acid, hexanesulfonic acid, peptanesulfonic acid, octanesulfonic acid, hydroxyethane Examples include sulfonic acids, hydroxypropanesulfonic acid, hydroxybutanesulfonic acid, hydroxypentanesulfonic acid, hydroxyhexanesulfonic acid, hydroxyheptanesulfonic acid, hydroxyoctanesulfonic acid, aminoethanesulfonic acid, aminopropanesulfonic acid, aminobutanesulfonic acid, aminopentanesulfonic acid, aminohexanesulfonic acid, aminoheptanesulfonic acid, or sulfonic acid compounds such as aminooctanesulfonic acid, benzenesulfonic acid, nitrobenzenesulfonic acid, dinitrobenzenesulfonic acid, pyridinesulfonic acid (the listed aromatic sulfonic acid compounds include their respective isomer compounds); or phosphorus compounds such as ethylphosphonic acid, propylphosphonic acid, butylphosphonic acid, pentylphosphonic acid, heptylphosphonic acid, octylphosphonic acid, isopropylphosphonic acid, isobutylphosphonic acid, isopentylphosphonic acid, isoheptylphosphonic acid, or isooctylphosphonic acid.

[0027] Among these, from the viewpoint of efficiently etching silicon nitride, organic acids that do not contain one or more aromatic rings selected from sulfonic acid compounds and carboxylic acid compounds are preferred, sulfonic acid compounds are more preferred, organic acids that do not contain one or more aromatic rings selected from alkyl sulfonic acid and phenyl sulfonic acid are even more preferred, and methanesulfonic acid is particularly preferred in terms of raising the boiling point of the etching solution.

[0028] Similar to sulfuric acid, organic acids that do not contain aromatic rings are preferable to etching solutions with low metal concentrations. Therefore, it is preferable to use organic acids that contain as few metal impurities and insoluble impurities as possible, and commercially available products can be purified and used as needed.

[0029] [Boron compound (component B)] The etching solution contains a boron compound (component B). The inclusion of the boron compound increases the etching rate of the silicon nitride. Boron compounds may be used individually or in combination of two or more types. Furthermore, there are no particular restrictions on the method of producing the boron compound; compounds synthesized by known methods may be used, or commercially available products may be used.

[0030] The inventors speculate on the reason for this as follows: When an aqueous solution containing a specific acid is used as an etching solution, the inventors have confirmed from an Arrhenius plot of the etching rate of silicon nitride that, at etching temperatures above a specific temperature (for example, 150°C in the case of a 75% by mass sulfuric acid aqueous solution), the slope of the etching rate of silicon nitride with respect to temperature increase (corresponding to the activation energy) becomes smaller compared to at temperatures below that specific temperature. In other words, at temperatures above a specific temperature, the increase in the etching rate of silicon nitride with respect to temperature increase tended to be smaller. This indicates that when an aqueous solution containing a specific acid is used as an etching solution, the rate-limiting process of etching silicon nitride changes around a specific temperature.

[0031] Furthermore, the etching temperature (turning point) at which the rate-determining process changes tended to shift to lower temperatures as the concentration of the specific acid in the aqueous solution increased. From these findings, it is considered that the rate-determining process at temperatures higher than the turning point is a process in which an increase in water content contributes to an increase in the etching rate of the silicon nitride. One such process in which an increase in water content is thought to contribute to an increase in the etching rate of the silicon nitride is the dissolution of the silicate compound produced by the etching reaction. The inventors surmise that the rate-determining process at temperatures higher than the turning point is the dissolution of the silicate compound.

[0032] On the other hand, when an aqueous solution containing a boron compound in a specific acid solution was used as an etching solution, the slope of the etching rate of silicon nitride with respect to temperature (corresponding to the activation energy) in the Arrhenius plot for the etching rate of silicon nitride did not change at both the temperature below a specific temperature and the temperature above it. From this, the inventors surmise that the inclusion of the boron compound promoted the dissolution of the silicate compound produced by the etching reaction. The inventors speculate that the dissolution of the silicic acid compound is promoted because, in etching with a specific acid aqueous solution, the silicic acid compound becomes oligomerized and difficult to dissolve, or recombines with silicon atoms on the silicon substrate surface and becomes difficult to dissolve. However, by including a boron compound, the silicic acid compound combines with the boron compound to form borosilicate, improving the solubility of the compound in water, while suppressing the oligomerization of the silicic acid compound and its recombination with silicon atoms on the silicon substrate surface.

[0033] A boron compound is a compound that contains boron (B) as a constituent element. There are no particular limitations on the boron compound used in etching solutions, but from the viewpoint of bonding with silicate compounds, it is preferable that it be at least one compound selected from the group consisting of boric acid compounds and boronic acid compounds. Examples include boric acid, borate salts, boric anhydride (boron oxide), metaboric acid, perboric acid, subboric acid, and polymers of boric acid. From the viewpoint of stability, it is more preferable that it be one or more compounds selected from the group consisting of boric acid, borate salts, boric anhydride, and polymers of boric acid, and it is even more preferable that it be one or more compounds selected from the group consisting of boric acid, boric anhydride, and polymers of boric acid.

[0034] The form of the boron compound is not particularly limited, but it is preferable that it is a boron compound that does not contain fluorine atoms. If a fluorine compound is contained in the etching solution whose pH is within the above range according to this embodiment, free hydrogen fluoride may be generated. Since free hydrogen fluoride is easily volatile from the etching solution, it can cause fluctuations in the etching properties of the etching solution. Furthermore, if hydrogen fluoride is present in the etching solution, not only will the etching rate of silicon nitride increase, but the etching rate of silicon oxide will also increase significantly, making it difficult to etch only the silicon nitride. Moreover, from a similar viewpoint, it is preferable that the etching solution does not contain compounds that generate hydrogen fluoride, and it is even more preferable that it does not contain compounds that contain fluorine atoms.

[0035] The etching solution disclosed in Patent Document 1 contains a boron compound containing fluorine, and therefore it is presumed to contain hydrogen fluoride produced by the hydrolysis of the boron compound. In particular, since the etching solution in Patent Document 1 is strongly acidic, it is presumed that the hydrogen fluoride exists mainly as volatile free hydrogen fluoride, rather than in the form of fluoride ions. On the other hand, since the etching solution according to this embodiment uses a boron compound that does not contain fluorine atoms as the boron compound, it does not generate easily volatile free hydrogen fluoride, and can efficiently etch silicon nitride. Furthermore, since the etching solution of this embodiment has a pH of 5.0 or less when diluted 10 times by mass and measured at 24°C, it is less likely to experience a decrease in the boiling point of the etching solution caused by a pH that is too high (i.e., a specific acid concentration that is too low), making it easier to control the temperature conditions during etching. The etching solution described above is particularly useful as an etching solution used when etching silicon nitride for microfabrication during the manufacturing of semiconductor devices. Furthermore, the etching solution according to this embodiment has the effect of having a high etching selectivity ratio of silicon nitride to at least one selected from the group consisting of silicon (Si) and silicon oxide (SiO2). Therefore, it is particularly useful as an etching solution for etching silicon nitride from a substrate or the like that has at least one selected from the group consisting of silicon and silicon oxide, and silicon nitride. In addition, with the etching solution according to this embodiment, the etching selectivity ratio of silicon nitride to silicon can be improved by using a boron compound that does not contain fluorine atoms, and furthermore, the etching selectivity ratio of silicon nitride to silicon oxide can be improved by setting the concentration of the boron compound that does not contain fluorine atoms within a predetermined range.

[0036] Examples of boron compounds containing a fluorine atom include at least one compound selected from the group consisting of boric acid compounds containing a fluorine atom and boronic acid compounds containing a fluorine atom. Examples of boron compounds not containing a fluorine atom include at least one compound selected from the group consisting of boric acid compounds not containing a fluorine atom and boronic acid compounds containing a fluorine atom. Examples of boric acid compounds that do not contain fluorine atoms include, for example, boric acid, borates, and boric anhydride, as well as polymers of boric acid; and one or more compounds selected from the group consisting of boric acid esters such as trimethylboric acid, triethylboric acid, triisopropylboric acid, tributylboric acid, trihexylboric acid, tri-o-toluylboric acid, and trimethylboroxine. Examples of boric acid compounds that contain fluorine atoms include fluorides of these boric acid compounds, specifically fluoroboric acid, difluoroboric acid, trifluoroboric acid, tetrafluoroboric acid, or trifluoromethylboric acid. Examples of boronic acid compounds that do not contain a fluorine atom include one or more compounds selected from the group consisting of alkylboronic acids such as ethylboronic acid, propylboronic acid, butylboronic acid, isobutylboronic acid, pentylboronic acid, hexylboronic acid, heptylboronic acid, octylboronic acid, cyclopentylboronic acid, and cyclohexylboronic acid, and arylboronic acids such as phenylboronic acid, naphthaleneboronic acid, anthraceneboronic acid, and phenylenediboronic acid. Examples of boronic acid compounds that contain a fluorine atom include fluorides of these boric acid compounds, specifically fluoroethylboronic acid, fluoropropylboronic acid, or fluorobutylboronic acid.

[0037] Among these, one or more compounds selected from the group consisting of boric acid, borate salts, boric anhydride, and polymers of boric acid are preferred in terms of their effect in suppressing the formation of by-products in the etching solution, with boric acid being more preferred in terms of ease of handling. The borate is a salt of boric acid or a polymer of boric acid, and examples include metal salts such as sodium tetraborate or sodium perborate, or nonmetal salts such as ammonium borate, but nonmetal salts are preferred. The cation in the borate is preferably an ammonium ion. For this reason, various ammonium salts such as unsubstituted ammonium salts, primary ammonium salts, secondary ammonium salts, tertiary ammonium salts, or quaternary ammonium salts are preferred as borates, and among these, unsubstituted ammonium salts are particularly preferred in terms of suppressing a decrease in the boiling point of the etching solution. Examples of the unsubstituted ammonium salt include ammonium pentaborate octahydrate.

[0038] The concentration (content) of the boron compound in the etching solution is not particularly limited, but a higher concentration of the boron compound improves the etching performance of the etching solution, tends to increase the etching rate of silicon nitride, and can improve the productivity of semiconductor devices. Therefore, the concentration of the boron compound in the etching solution is usually 0.1% by mass or more, preferably 0.20% by mass or more, more preferably 0.40% by mass or more, and even more preferably 0.80% by mass or more. A concentration of 1.00% by mass or more is particularly preferred. Furthermore, the upper limit of the concentration is not particularly limited, but in terms of the solubility of the boron compound in water, it may be 30.00% by mass or less, 20.00% by mass or less, 15.00% by mass or less, or 10.00% by mass or less. Specifically, it is preferably 0.10% by mass or more and 30.00% by mass or less, more preferably 0.10% by mass or more and 20.00% by mass or less, even more preferably 0.10% by mass or more and 15.00% by mass or less, even more preferably 0.40% by mass or more and 15.00% by mass or less, even more preferably 0.80% by mass or more and 15.00% by mass or less, and most preferably 0.80% by mass or more and 10.00% by mass or less. By keeping the boron compound concentration within the above range, silicon nitride can be etched at a sufficient etching rate.

[0039] [Silicon compounds (component C)] The etching solution contains a silicon compound (component C) having at least one Si-O bond and at least one Si-C bond. In this embodiment, the silicon compound is used as a silicon etching inhibitor. As described above, by including the above-mentioned silicon compound in the etching solution, the etching efficiency of silicon nitrides onto silicon or silicon oxides can be improved. The silicon compound may be linear, branched, cyclic, or have a cyclic structure. Silicon compounds may be used individually or in combination of two or more types. Furthermore, there are no particular restrictions on the method of producing the silicon compound; it may be synthesized by known methods or a commercially available product may be used.

[0040] The total concentration of silicon compounds in the etching solution is not particularly limited, but from the viewpoint of suppressing the generation of particles, it is preferably 0.01 ppm or more and less than 1000 ppm by mass, more preferably 0.1 ppm or more and less than 1000 ppm by mass, more preferably 0.1 ppm or more and less than 800 ppm by mass, and even more preferably 0.5 ppm or more and less than 500 ppm by mass.

[0041] The silicon compound is preferably a silicon compound (component C) containing an organic group. The type of organic group is not particularly limited and examples include hydrophobic groups such as a linear alkyl group having 1 to 10 carbon atoms which may have substituents, a branched alkyl group having 3 to 10 carbon atoms which may have substituents, a cyclic alkyl group having 3 to 10 carbon atoms which may have substituents, an aryl group having 5 to 12 carbon atoms which may have substituents, a linear alkenyl group having 3 to 10 carbon atoms which may have substituents, a branched alkenyl group having 3 to 10 carbon atoms which may have substituents, a linear alkynyl group having 2 to 10 carbon atoms which may have substituents, a linear alkoxy group having 2 to 10 carbon atoms which may have substituents, an epoxy group, a styryl group, a metasyloxy group, an acyloxy group, an amino group, a ureido group, an isocyanate group, an isocyanurate group, or a mercapto group.

[0042] The substituents used herein are not particularly limited, but examples include epoxy groups, styryl groups, metasyloxy groups, acyloxy groups, amino groups, ureido groups, isocyanate groups, isocyanurate groups, or mercapto groups.

[0043] From the viewpoint of suppressing particle generation, linear alkyl groups having 1 to 10 carbon atoms are preferably linear alkyl groups having 1 to 5 carbon atoms, more preferably linear alkyl groups having 1 to 3 carbon atoms, and even more preferably linear alkyl groups having 1 to 2 carbon atoms (methyl group, ethyl group). From the viewpoint of suppressing particle generation, branched alkyl groups with 3 to 10 carbon atoms are preferably branched alkyl groups with 1 to 5 carbon atoms, and branched alkyl groups with 1 to 3 carbon atoms are also preferred. It is more preferably a C1 group, and even more preferably a branched alkyl group having 1 to 2 carbon atoms. From the viewpoint of suppressing particle generation, cyclic alkyl groups having 3 to 10 carbon atoms may also be cyclic alkyl groups having 3 to 5 carbon atoms. From the viewpoint of suppressing particle generation, the aryl group having 5 to 12 carbon atoms may also be an aryl group having 5 to 8 carbon atoms. From the viewpoint of suppressing particle generation, the linear alkenyl group having 3 to 10 carbon atoms may also be a linear alkenyl group having 3 to 5 carbon atoms. From the viewpoint of suppressing particle generation, branched alkenyl groups with 3 to 10 carbon atoms may also be branched alkenyl groups with 3 to 5 carbon atoms. From the viewpoint of suppressing particle generation, the linear alkynyl group having 2 to 10 carbon atoms may also be a linear alkynyl group having 2 to 5 carbon atoms. From the viewpoint of suppressing particle generation, the linear alkoxy group having 2 to 10 carbon atoms may also be a linear alkoxy group having 2 to 5 carbon atoms.

[0044] Examples of silicon compounds containing organic groups include, for example, silicon compounds containing the above-mentioned organic groups, and preferably silicon compounds that include a structure in which the above-mentioned organic groups are bonded to silicon atoms.

[0045] The average number of Si-O bonds per silicon atom in a silicon compound is not particularly limited, but from the viewpoint of solubility, it is preferably 1 to 10, and more preferably 2 to 5.

[0046] Silicon compounds containing organic groups include, specifically, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, trimethylalkoxysilane, dimethyldialkoxysilane, methyltrialkoxysilane, hexamethyldisilazane, and 1,3-divinyl-1,1,3,3-tetramethyldisilazane, poly(methylhydrosiloxane), triethoxysilane, silyl ether, polydimethylsiloxane, cyclic siloxane, trimethylethoxysilane, trimethoxymethylsilane, dimethoxydimethylsilane, triethoxymethylsilane, diethoxydimethylsilane, trimethoxysilane, dimethoxymethylsilane, diisopropyldimethoxysilane, diethoxymethylsilane, dimethoxyvinylmethylsilane, dimethoxydivinylsilane, diethoxyvinylmethylsilane, trimethoxymethylsilane, 3-aminopropyltriethoxysilane, bis[[3-(trimethoxysilane [Lyl)propyl]amine, trimethoxy[3-(phenylamino)(propyl]silane, trimethyl[3-(triethoxysilyl)propyl]ammonium chloride, [3-(butylamino)propyl]trimethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, 3-(2-aminoethylamino)propyldimethoxymethylsilane, 3-aminopropyldimethoxymethylsilane, 3-(ethoxydimethylsilyl)propan-1-amine, [3-(6-aminohexylamino)propyl]trimethoxysilane, Examples include [3-[(2-aminoethyl)amino]propyl]diethoxy(methyl)silane, 3-aminopropyldiethoxymethylsilane, 3-(methylamino)propyltriethoxysilane, 3-(2-aminoethylamino)propyltriethoxysilane, [3-(N,N-dimethylamino)propyl]trimethoxysilane, 3-aminopropyltrimethoxysilane, bis[3-(triethoxysilyl)propyl]amine, trimethoxy[3-(methylamino)propyl]silane, trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride, or diethoxydivinylsilane. Among these compounds, those for which isomers exist also include the isomers.

[0047] The organosilicon compound is preferably represented by one of the following formulas (1) to (3).

[0048] [ka]

[0049] In equations (1) to (3) above, R 1 ~R 4Each of these independently represents a hydrogen atom, a hydroxyl group, an optionally substituted C5-C12 aryl group, an optionally substituted C2-C10 linear alkenyl group, an optionally substituted C3-C10 branched alkenyl group, an optionally substituted C2-C10 linear alkynyl group, or an optionally substituted C2-C10 linear alkoxy group; R 1 ~R 4 One or more of these independently have a hydrophobic group capable of forming a Si-C bond with the Si represented in formula (1); R 1 ~R 4 One or more of these independently have a hydrophobic group capable of forming a Si-O bond with the Si represented in formula (1); R 11 ~R 16 and R 21 ~R 26 Each independently represents a hydrogen atom, a hydroxyl group, a C1-C10 linear alkyl group which may have substituents, a C3-C10 branched alkyl group which may have substituents, a C3-C10 cyclic alkyl group which may have substituents, an aryl group which may have substituents, a C5-C12 linear alkenyl group which may have substituents, a C2-C10 linear alkenyl group which may have substituents, a C3-C10 branched alkenyl group which may have substituents, a C2-C10 linear alkynyl group which may have substituents, or a C2-C10 linear alkoxy group which may have substituents; R 11 ~R 16 One or more of these independently have a hydrophobic group capable of forming a Si-C bond with the Si represented in formula (2); R 21 ~R 26 One or more of these independently have a hydrophobic group capable of forming a Si-C bond with the Si represented in formula (3); n 11 n is an integer between 1 and 10; 21is an integer from 1 to 10. The substituents are not particularly limited, but are preferably, for example, an epoxy group, a styryl group, a metasyloxy group, an acyloxy group, an amino group, a ureido group, an isocyanate group, an isocyanurate group, or a mercapto group, and are particularly preferably an amino group.

[0050] R 11 ~R 16 and R 21 ~R 26 From the viewpoint of solubility, each is preferably independently a linear alkyl group having 1 to 10 carbon atoms that may have substituents, a branched alkyl group having 3 to 10 carbon atoms that may have substituents, a cyclic alkyl group having 3 to 10 carbon atoms that may have substituents, or a linear alkoxy group having 2 to 10 carbon atoms that may have substituents, and more preferably a linear alkyl group having 1 to 10 carbon atoms or a linear alkoxy group having 2 to 10 carbon atoms.

[0051] R 1 ~R 3 One or more of these groups, from the viewpoint of suppressing nucleophilic attack, each independently has a hydrophobic group capable of forming a Si-C bond with the Si represented in formula (1). 1 ~R 3 The hydrophobic groups in are not particularly limited and can be, for example, aryl groups having 5 to 12 carbon atoms, linear alkenyl groups having 2 to 10 carbon atoms, branched alkenyl groups having 3 to 10 carbon atoms, linear alkynyl groups having 2 to 10 carbon atoms, or amino group-containing hydrocarbon groups having 2 to 10 carbon atoms. 1 ~R 3 If one or more of these are amino group-containing hydrocarbon groups, for example, the amino group-containing hydrocarbon group may have a Si-C bond (2 to 10 carbon atoms) and an amino group at its tip. In this embodiment, because there is a Si-C bond (2 to 10 carbon atoms) with Si, the area near the silicon substrate surface is made hydrophobic, suppressing nucleophilic attack. Among these, aryl groups with 5 to 12 carbon atoms, linear alkenyl groups with 2 to 10 carbon atoms, branched alkenyl groups with 3 to 10 carbon atoms, or linear alkynyl groups with 2 to 10 carbon atoms are preferred.

[0052] R 11 ~R 16 One or more of these groups, from the viewpoint of suppressing nucleophilic attack, each independently has a hydrophobic group capable of forming a Si-C bond with the Si represented in formula (1). Also, R 21 ~R 26 One or more of these groups, from the viewpoint of suppressing nucleophilic attack, each independently has a hydrophobic group capable of forming a Si-C bond with the Si represented in formula (1). The aforementioned R 11 ~R 16 and R 21 ~R 26 The hydrophobic group in is not particularly limited and can be any of the following independently: a linear alkyl group having 1 to 10 carbon atoms, a branched alkyl group having 3 to 10 carbon atoms, a cyclic alkyl group having 3 to 10 carbon atoms, an aryl group having 5 to 12 carbon atoms, a linear alkenyl group having 2 to 10 carbon atoms, a branched alkenyl group having 3 to 10 carbon atoms, a linear alkynyl group having 2 to 10 carbon atoms, or an amino group-containing hydrocarbon group having 2 to 10 carbon atoms. Among these, it is preferable that the group be a linear alkyl group having 1 to 10 carbon atoms, a branched alkyl group having 3 to 10 carbon atoms, a cyclic alkyl group having 3 to 10 carbon atoms, an aryl group having 5 to 12 carbon atoms, a linear alkenyl group having 2 to 10 carbon atoms, a branched alkenyl group having 3 to 10 carbon atoms, or a linear alkynyl group having 2 to 10 carbon atoms, and more preferably a linear alkyl group having 1 to 10 carbon atoms.

[0053] Examples of amino group-containing hydrocarbon groups include C1-C10 linear alkyl groups substituted with an amino group, C3-C10 branched alkyl groups substituted with an amino group, C3-C10 cyclic alkyl groups substituted with an amino group, C5-C12 aryl groups substituted with an amino group, C3-C10 linear alkenyl groups substituted with an amino group, C3-C10 branched alkenyl groups substituted with an amino group, C2-C10 linear alkynyl groups substituted with an amino group, or C2-C10 linear alkoxy groups substituted with an amino group. Among these, it is preferable that the linear alkyl group having 1 to 10 carbon atoms substituted with an amino group, the branched alkyl group having 3 to 10 carbon atoms substituted with an amino group, the cyclic alkyl group having 3 to 10 carbon atoms substituted with an amino group, or the linear alkoxy group having 2 to 10 carbon atoms substituted with an amino group.

[0054] n 11 The integer is between 1 and 10, but it may also be between 1 and 8, or between 1 and 5.

[0055] n 21 This can be an integer between 1 and 10, but it can also be an integer between 1 and 8, or an integer between 1 and 5.

[0056] Another embodiment of the present invention described above, the silicon etching inhibitor, is a silicon etching inhibitor (second embodiment of the present invention; also simply referred to as "silicon etching inhibitor") comprising an organosilicon compound having at least one Si-O bond and one Si-C bond. The etching inhibitor according to this embodiment is used to etch materials such as silicon or silicon oxide. It can effectively suppress ching. The silicon etching inhibitor can be subjected to the same conditions as those for the silicon compound (component C) described above. In this specification, "consisting of" may be rephrased as "consisting of only".

[0057] The manner in which silicon etching inhibitors are used is not particularly limited, and they may be used not only in the form in which they are manufactured and sold as silicon etching inhibitors, but also in the form in which they are included in products such as silicon etching solutions. The form in which silicon etching inhibitors are manufactured and sold includes not only the form in which they are manufactured and sold as products containing only organosilicon compounds having at least one Si-O bond and one Si-C bond, but also the form in which they are manufactured and sold as silicon etching inhibitors in the form of a composition containing the organosilicon compound as the main component and also containing other components.

[0058] [water] The etching solution contains water. If water is not present, the etching rate tends to decrease. Depending on the type and amount of other components, the concentration (percentage) of water in the etching solution is preferably 5.0% by mass or more and less than 40.0% by mass, more preferably 10.0% by mass or more and less than 40.0% by mass, even more preferably 10.0% by mass or more and less than 35.0% by mass, and particularly preferably 10.0% by mass or more and less than 30.0% by mass. Furthermore, for example, the remainder of the etching solution other than the specific acid and the boron compound that does not contain fluorine atoms may be water. In addition, if the etching solution contains components such as an etching inhibitor for silicon or silicon oxide or a basic compound, the remainder of the etching solution other than the specific acid, the boron compound that does not contain fluorine atoms, and the said components may be water.

[0059] The type of water is not particularly limited, but it is preferable to use high-purity water with few impurities. Water with few impurities can be easily manufactured and obtained as ultrapure water for semiconductor manufacturing. The amount of impurities in the etching solution can be evaluated by its electrical resistivity. Specifically, the electrical resistivity is preferably 0.10 MΩ·cm or higher, more preferably 15.00 MΩ·cm or higher, and even more preferably 18.00 MΩ·cm or higher. The upper limit is not particularly limited, but it may be 18.25 MΩ·cm or lower. That is, preferably, for example, 0.10 MΩ·cm or higher and 18.25 MΩ·cm or lower, 15.00 MΩ·cm or higher and 18.25 MΩ·cm or lower, and 18.00 MΩ·cm or higher and 18.25 MΩ·cm or lower. As mentioned above, water with such low impurity levels can be easily manufactured and obtained as ultrapure water for semiconductor manufacturing. Furthermore, ultrapure water has significantly fewer impurities that do not affect (or have little to no effect on) electrical resistivity, making it highly suitable as a raw material for etching solutions.

[0060] Furthermore, among the metals, it is preferable that the amount of any one metal selected from the group consisting of Fe, Cu, Mn, Cr, and Zn is small. The concentration of any one metal selected from these groups in the water used as a raw material is preferably 0.01 ppt to 1.00 ppb by mass, more preferably 0.01 ppt to 0.50 ppb, even more preferably 0.01 ppt to 0.20 ppb, and particularly preferably 0.01 ppt to 0.1 ppb. In particular, it is preferable that this range is satisfied for all of the metals Fe, Cu, Mn, Cr, and Zn.

[0061] [Other ingredients] The etching solution may further contain components other than those described above (other components) to the extent that the effects of the present invention can be obtained, and an example of such components is shown below.

[0062] (Basic compound (component E)) The etching solution may also contain a basic compound (component E), or it may not contain one. This is also acceptable. By including a basic compound, the pH of the etching solution can be increased. As mentioned above, etching of silicon nitride proceeds by the protonation of the nitrogen sites of silicon nitride, followed by nucleophilic attack of water or hydroxide ions on the silicon sites. Therefore, under conditions where the nucleophilic reaction by hydroxide ions is the rate-limiting factor in the etching of silicon nitride, increasing the pH of the etching solution by including a basic compound may improve the etching rate of silicon nitride. Basic compounds may be used individually or in combination of two or more. Furthermore, there are no particular restrictions on the method of producing the basic compound; it may be synthesized by known methods or used as a commercially available product.

[0063] The basic compound is not particularly limited as long as it reacts with the specific acid to form a salt of the specific acid, but it is preferably ammonia or an organic base, or a salt thereof, and more preferably one or more selected from the group consisting of ammonia, amines, and tetraalkylammonium hydroxides. Furthermore, the salt is preferably a salt of an acid having a pKa equal to or greater than that of the specific acid, and ammonia or an organic base. If the acid is a polyhydric acid, it is acceptable even if the first pKa is less than the pKa of the specific acid, as long as the second or third pKa is equal to or greater than the pKa of the specific acid. Examples of organic bases include onium hydroxide or organic amines.

[0064] Examples of ammonium hydroxides include primary ammonium hydroxide, secondary ammonium hydroxide, tertiary ammonium hydroxide, or quaternary ammonium hydroxide, as well as phosphonium hydroxide, sulfonium hydroxide, iminium hydroxide containing multiple bonds, or diazenium hydroxide. Among these, ammonium hydroxide is preferred, and quaternary ammonium hydroxide is more preferred from the viewpoint of having good stability against specific acids (especially sulfuric acid) and being able to improve the stability of the etching solution over time.

[0065] As the quaternary ammonium hydroxide, one or more selected from the group consisting of tetramethylammonium hydroxide, ethyltrimethylammonium hydroxide, propyltrimethylammonium hydroxide, butyltrimethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, trimethyl-2-hydroxyethylammonium hydroxide, dimethylbis(2-hydroxyethyl)ammonium hydroxide, methyltris(2-hydroxyethyl)ammonium hydroxide, phenyltrimethylammonium hydroxide, and benzyltrimethylammonium hydroxide can be used.

[0066] As the organic amine, one or more selected from the group consisting of primary amines, secondary amines, and tertiary amines can be used.

[0067] Examples of primary or secondary amines include ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,1,3,3-tetramethylguanidine, diethylenetriamine, dipropylenetriamine, bis(hexamethylene)triamine, N,N,N-trimethyldiethylenetriamine, and N,N-bis(3-aminopropyl)ethylenediamine. One or more substances selected from the group consisting of amines, 2-(2-aminoethoxy)ethanol, 2-amino-2-methyl-1-propanol, 4-amino-1-butanol, 5-amino-1-pentanol, 6-amino-1-hexanol, N-(2-aminoethyl)propanolamine, N-(2-hydroxypropyl)ethylenediamine, azetidine, pyrrolidine, piperidine, hexamethyleneimine, pentamethyleneimine, and octamethyleneimine can be used.

[0068] Furthermore, specific examples of tertiary amines include one or more selected from the group consisting of 2-(dimethylamino)ethanol, 3-(dimethylamino)-1-propanol, 4-dimethylamino-1-butanol, 2-(diethylamino)ethanol, triethylamine, methylpyrrolidine, methylpiperidine, 1,8-diazabicyclo[5.4.0]undeca-7-ene, and 1,5-diazabicyclo[4.3.0]non-5-ene.

[0069] Preferably, the organic amine can be one or more selected from the group consisting of ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,1,3,3-tetramethylguanidine, diethylenetriamine, dipropylenetriamine, bis(hexamethylene)triamine, 2-(2-aminoethoxy)ethanol, 2-amino-2-methyl-1-propanol, 4-amino-1-butanol, 5-amino-1-pentanol, 6-amino-1-hexanol, N-(2-aminoethyl)propanolamine, pyrrolidine, piperidine, hexamethyleneimine, and pentamethyleneimine. More preferably, one or more can be selected from the group consisting of ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,1,3,3-tetramethylguanidine, diethylenetriamine, dipropylenetriamine, bis(hexamethylene)triamine, 2-(2-aminoethoxy)ethanol, 2-amino-2-methyl-1-propanol, pyrrolidine, and piperidine.

[0070] Such basic compounds should be selected and used according to their known characteristics, taking into account the target and purpose of etching. As mentioned above, quaternary ammonium hydroxide is more preferred among the above in terms of stability against specific acids. On the other hand, from the viewpoint of suppressing the decrease in the boiling point of the etching solution due to the addition of basic compounds, compounds with a small molar mass relative to the number of nitrogen atoms (molar mass / number of nitrogen atoms) are preferred. Specifically, ammonia or polyamine compounds are preferred. Examples of polyamine compounds include ethylenediamine, diaminopropane, diethylenetriamine, or dipropylenetriamine.

[0071] Furthermore, as will be discussed later, since etching solutions are preferable to have a low concentration of metal, it is preferable to use basic compounds that contain as few metal impurities and insoluble impurities as possible. Commercially available products can be purified by recrystallization, column purification, ion exchange purification, or filtration as needed before use. When using quaternary ammonium hydroxide as the basic compound, depending on the type, extremely high-purity versions are manufactured and sold for semiconductor manufacturing, and it is preferable to use such products. High-purity quaternary ammonium hydroxide for semiconductor manufacturing, which is generally sold, can be used as an aqueous solution or other solution. When manufacturing the etching solution, this solution can be mixed directly with water and other components.

[0072] The concentration of the basic compound in the etching solution is not particularly limited, but it is preferably 0.05 molar equivalents or more relative to the specific acid in the etching solution. A higher molar equivalent relative to the specific acid in the etching solution leads to a higher pH of the etching solution (i.e., a higher hydroxide ion concentration), which tends to increase the etching rate of silicon nitride and improves the productivity of semiconductor devices. Therefore, the concentration of the basic compound is more preferably 0.05 molar equivalents or more, even more preferably 0.10 molar equivalents or more, and particularly preferably 0.25 molar equivalents or more relative to the specific acid in the etching solution. Furthermore, there is no particular upper limit, but in order to suppress the decrease in the boiling point of the etching solution due to the addition of the basic compound, it may be 1.50 molar equivalents or less, 1.00 molar equivalents or less, or 0.75 molar equivalents or less. That is, preferably, for example, 0.05 molar equivalents or more and 1.50 molar equivalents or less, 0.10 molar equivalents or more and 1.00 molar equivalents or less, 0.10 molar equivalents or more and 0.75 molar equivalents or less, and 0.25 molar equivalents or more and 0.75 molar equivalents. The following ranges are listed. Note that the above ranges apply when the specific acid and the basic compound react in a 1:1 ratio. When the specific acid and the basic compound react in a 2:1 or 3:1 ratio, the concentration range of the basic compound will be halved or halved, respectively, for both the upper and lower limits. Specifically, examples of the range of the basic compound when the specific acid and the basic compound react in a 2:1 ratio include, for example, 0.025 molar equivalents or more and 0.750 molar equivalents or less, 0.050 molar equivalents or more and 0.500 molar equivalents or less, 0.050 molar equivalents or more and 0.375 molar equivalents or less, and 0.125 molar equivalents or more and 0.375 molar equivalents or less.

[0073] (Other etching inhibitors (component F)) The etching solution may further contain etching inhibitors other than the silicon compound (component C) described above (component F, other etching inhibitors). The other etching inhibitors shown below can inhibit the etching of not only silicon but also silicon oxide, and therefore can improve the efficiency of selectively etching silicon nitride with at least one selected from the group consisting of silicon and silicon oxide. Other etching inhibitors are used with the expectation of obtaining an etching inhibitory effect on silicon or silicon oxide through adsorption due to hydrophobic and electrostatic interactions with the surface of silicon or silicon oxide. Other etching inhibitors may be used individually or in combination of two or more. Furthermore, there are no particular limitations on the manufacturing method of other etching inhibitors; those synthesized by known methods may be used, or commercially available products may be used.

[0074] The etching inhibitor for silicon or silicon oxide is not particularly limited as long as it is a compound that adsorbs onto the surface of silicon or silicon oxide. Specifically, examples of etching inhibitors for silicon or silicon oxide include one or more selected from nonionic compounds, anionic compounds having hydrophobic groups, and amphoteric compounds having hydrophobic groups. Among these, from the viewpoint of having good stability against specific acids (especially sulfuric acid) and being able to improve the stability of the etching solution over time, cationic compounds having hydrophobic groups and amphoteric compounds having hydrophobic groups are preferred, and from the viewpoint of adsorption to the surface of silicon or silicon oxide, anionic compounds having hydrophobic groups and cationic compounds having hydrophobic groups are more preferred, with cationic compounds having hydrophobic groups being even more preferred. Here, a hydrophobic group refers to a functional group having a hydrocarbon chain, such as an alkyl group or an aryl group.

[0075] It should be noted that the range of "anionic compounds" may overlap with the "specific acids" mentioned above. However, specific acids play the role of base components, while anionic compounds play the role of additives, i.e., auxiliary agents, and their respective roles are different. Therefore, they can be distinguished by their concentration. Specifically, they can be distinguished by the fact that the concentration of each compound included as a specific acid (component A) is 10% by mass or more, and the total concentration of the other compounds included as etching inhibitors (component F) is less than 10% by mass. In this case, for example, if the etching solution contains 60% by mass of methanesulfonic acid and 5% by mass of hexanesulfonic acid, methanesulfonic acid is treated as a specific acid and hexanesulfonic acid as an etching inhibitor. Also, if the etching solution contains 60% by mass of sulfuric acid and 5% by mass of methanesulfonic acid, sulfuric acid is treated as a specific acid and methanesulfonic acid as an etching inhibitor.

[0076] Examples of anionic compounds having hydrophobic groups include butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, isobutanoic acid, isopentanoic acid, isohexanoic acid, isoheptanoic acid, isooctanoic acid, 2-cyclobutylacetic acid, cyclopentanecarboxylic acid, cyclo Carboxylic acid compounds such as hexanecarboxylic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, tridecanediic acid, methylsuccinic acid, or tetramethylsuccinic acid (the listed aromatic carboxylic acid compounds include their respective isomers); Sulfonic acid compounds such as methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, butanesulfonic acid, pentanesulfonic acid, hexanesulfonic acid, peptanesulfonic acid, octanesulfonic acid, hydroxyethanesulfonic acid, hydroxypropanesulfonic acid, hydroxybutanesulfonic acid, hydroxypentanesulfonic acid, hydroxyhexanesulfonic acid, hydroxyheptanesulfonic acid, hydroxyoctanesulfonic acid, aminoethanesulfonic acid, aminopropanesulfonic acid, aminobutanesulfonic acid, aminopentanesulfonic acid, aminohexanesulfonic acid, aminoheptanesulfonic acid, aminooctanesulfonic acid, toluenesulfonic acid, aminobenzenesulfonic acid, benzenesulfonic acid, nitrobenzenesulfonic acid, dinitrobenzenesulfonic acid, or pyridinesulfonic acid (the listed aromatic sulfonic acid compounds include their respective isomers); or Examples include phosphorus compounds such as ethylphosphonic acid, propylphosphonic acid, butylphosphonic acid, pentylphosphonic acid, heptylphosphonic acid, octylphosphonic acid, isopropylphosphonic acid, isobutylphosphonic acid, isopentylphosphonic acid, isoheptylphosphonic acid, or isooctylphosphonic acid.

[0077] Examples of nonionic compounds include glycols such as ethylene glycol, propylene glycol, and dipropylene glycol, and polyol compounds having multiple hydroxyl groups, such as glycerin; Examples include glycol ether compounds such as alkylene glycol monoalkyl esters like ethylene glycol monopropyl ether, ethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, or diethylene glycol n-butyl ether, or alkylene glycol dialkyl esters like diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, or diethylene glycol diethyl ether.

[0078] Examples of cationic compounds having hydrophobic groups include tetramethylammonium chloride, tetramethylammonium bromide, tetraethylammonium chloride, tetraethylammonium bromide, tetrapropylammonium chloride, tetrapropylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium bromide, dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, decyltrimethylammonium chloride, decyltrimethylammonium Examples include halogen salts of quaternary ammonium, sulfates of quaternary ammonium, or hydrogen sulfates of quaternary ammonium, such as umbromide, decamethonium dichloride, decamethonium dibromide, hexamethonium dichloride, hexamethonium dibromide, 1,1'-(decane-1,10-diyl)bis[4-aza-1-azoniabicyclo[2.2.2]octane]dibromide, and 1,1'-(decane-1,10-diyl)bis[4-aza-1-azoniabicyclo[2.2.2]octane]dichloride. The sulfates of quaternary ammonium may be produced by reacting quaternary ammonium hydroxide with sulfuric acid and included in the etching solution. As mentioned above, sulfuric acid is treated as a specific acid if it is present in the etching solution at a concentration of 10% by mass or more.

[0079] The above cationic compounds are preferably cationic compounds having two or more cationic sites in their structure, from the viewpoint of increasing adsorption (increasing the probability of adsorption and decreasing the probability of desorption). For example, decamethonium dichloride, decamethonium dibromide, hexamethonium dichloride, hexamethonium dibromide, 1,1'-(decane-1,10-di Examples include yl)bis[4-aza-1-azoniabicyclo[2.2.2]octane]dibromide or 1,1'-(decane-1,10-diyl)bis[4-aza-1-azoniabicyclo[2.2.2]octane]dichloride. Among these, cationic compounds in which the alkyl chain between the two cationic sites has 8 or fewer carbon atoms are even more preferred in terms of stability to high temperatures and sulfuric acid. Specifically, examples include hexamethonium dichloride or hexamethonium dibromide.

[0080] Examples of amphoteric compounds having hydrophobic groups include amino acid compounds such as methylglycine, ethylglycine, alanine, β-alanine, leucine, isoleucine, proline, hydroxyproline, N-methylproline, α-methylproline, or tyrosine.

[0081] The etching inhibitor for silicon or silicon oxide can be one or more compounds selected from the group consisting of the compounds listed above.

[0082] From the viewpoint described below, the etching solution preferably contains a cationic compound having a hydrophobic group as an etching inhibitor, and more preferably a compound having multiple cationic parts, with hydrophobic parts between the multiple cationic parts. Among the multiple compounds listed above, compounds that adsorb to the substrate surface due to either hydrophobic interactions, electrostatic interactions, or both are preferably used. Since the surface of hydrogen-terminated silicon is hydrophobic and the surface of silicon nitride is hydrophilic, using a compound that adsorbs to the substrate surface due to hydrophobic interactions as an etching inhibitor can selectively suppress the etching of silicon relative to the etching of silicon nitride. In particular, when an organic acid is used as the specific acid, the silicon surface and silicon oxide surface to which the organic acid is bonded are hydrophobic, so using a compound that adsorbs to the substrate surface due to hydrophobic interactions as an etching inhibitor can efficiently suppress the etching of silicon or silicon oxide. Furthermore, when sulfuric acid is used as the specific acid, when sulfuric acid is adsorbed on the silicon surface or silicon oxide surface, the surface charge of each is negatively charged, so cationic compounds are easily adsorbed, and etching can be efficiently suppressed. On the other hand, the silicon nitride surface is positively charged due to protonation of nitrogen sites and is hydrophilic, so cationic compounds and compounds that adsorb to the substrate surface due to hydrophobic interactions are less likely to adsorb. When the etching solution contains sulfuric acid at a high concentration, it is preferable to use a compound with high stability to sulfuric acid as the etching inhibitor.

[0083] Compounds adsorbed onto the substrate surface by hydrophobic interactions are not particularly limited as long as they have hydrophobic groups. Specifically, compounds with high stability against certain acids include carboxylic acid compounds such as butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, isobutanoic acid, isopentanoic acid, isoheptanoic acid, isooctanoic acid, 2-cyclobutylacetic acid, cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, tridecanediic acid, methylsuccinic acid, tetramethylsuccinic acid, methylglycine, ethylglycine, alanine, β-alanine, leucine, isoleucine, proline, hydroxyproline, N-methylproline, α-methylproline, or tyrosine; One or more sulfonic acid compounds selected from the group consisting of ethanesulfonic acid, propanesulfonic acid, butanesulfonic acid, pentanesulfonic acid, hexanesulfonic acid, peptanesulfonic acid, octanesulfonic acid, hydroxyethanesulfonic acid, hydroxypropanesulfonic acid, hydroxybutanesulfonic acid, hydroxypentanesulfonic acid, hydroxyhexasulfonic acid, hydroxyheptanesulfonic acid, hydroxyoctanesulfonic acid, aminoethanesulfonic acid, aminopropanesulfonic acid, aminobutanesulfonic acid, aminopentanesulfonic acid, aminohexanesulfonic acid, aminoheptanesulfonic acid, or aminooctanesulfonic acid; etc. ru.

[0084] Compounds that adsorb to the substrate surface due to the effects of both hydrophobic and electrostatic interactions include, for example, aromatic ring compounds having electron-withdrawing groups such as nitrobenzene, dinitrobenzene, chloronitrobenzene, chlorodinitrobenzene, benzenesulfonic acid, nitrobenzenesulfonic acid, dinitrobenzenesulfonic acid, nitropyridine, hydroxynitropyridine, pyridinesulfonic acid, or aromatic compounds such as N8,N8,3-trimethyl-2,8-phenazinediamine (the listed compounds include their respective isomers); or tetramethylammonium chloride, tetramethylammonium bromide, tetraethylammonium chloride, tetraethylammonium bromide, tetrapropylammonium chloride, tetrapropylammonium bromide, tetrabutylammonium One or more examples selected from the group consisting of halogen salts of quaternary ammonium, sulfates of quaternary ammonium, or hydrogen sulfates of quaternary ammonium, such as ammonium chloride, tetrabutylammonium bromide, dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, decyltrimethylammonium chloride, decyltrimethylammonium bromide, decametonium chloride, decametonium bromide, hexamethonium chloride, hexamethonium bromide, 1,1'-(decane-1,10-diyl)bis[4-aza-1-azoniabicyclo[2.2.2]octane]dibromide, or 1,1'-(decane-1,10-diyl)bis[4-aza-1-azoniabicyclo[2.2.2]octane]dichloride; etc.

[0085] The total concentration of the etching inhibitor in the etching solution is not particularly limited, but may be, for example, 0.001% by mass or more and 20.000% by mass or less, 0.010% by mass or more and 10.000% by mass or less, preferably 0.005% by mass or more and less than 15.000% by mass, more preferably 0.005% by mass or more and less than 10.000% by mass, even more preferably 0.010% by mass or more and less than 7.500% by mass, and particularly preferably 0.020% by mass or more and less than 7.500% by mass. Furthermore, the concentration of each compound contained in the etching solution as an etching inhibitor is less than 10% by mass, may be 0.001% by mass or more and less than 10% by mass, preferably 0.005% by mass or more and less than 10.000% by mass, more preferably 0.010% by mass or more and less than 7.500% by mass, even more preferably 0.020% by mass or more and less than 7.500% by mass, and particularly preferably 0.020% by mass or more and less than 5.000% by mass. If the total concentration of the etching inhibitors and the concentration of each compound are above the lower limit of the above range, a sufficient etching inhibitory effect on silicon or silicon oxide can be obtained. Furthermore, if these concentrations are below the upper limit of the above range, a sufficient concentration of the specific acid and the amount of water can be ensured, and consequently, a sufficient etching rate for silicon nitride can be ensured.

[0086] (Polymerization inhibitor (component G)) The etching solution may further contain a polymerization inhibitor (component G) that suppresses the polymerization of the silicon compound (component C) described above. The form of the polymerization inhibitor is not particularly limited, and examples include aromatic ring compounds having electron-withdrawing groups. Polymerization inhibitors may be used individually or in combination of two or more types. Furthermore, there are no particular restrictions on the method of producing the polymerization inhibitor; it may be synthesized by known methods or a commercially available product may be used.

[0087] The silicon compound (component C) can be hydrolyzed in a strong acid to produce silicon compounds having multiple silanol groups, such as silicic acid. Silicic acid can also be produced by etching silicon nitride. The silicon compounds thus produced, having multiple silanol groups, can be polymerized by condensation of the silanol groups. If the silicic acid concentration in the etching solution is high... This can lead to problems such as polymerization and precipitation, or gelation. When the electron-withdrawing group of an aromatic ring compound having an electron-withdrawing group condenses with the silanol group of a silicon compound having multiple silanol groups, such as silicic acid, the silanol group is capped, and polymerization of the silicon compound having multiple silanol groups, such as silicic acid, can be suppressed.

[0088] The type of electron-withdrawing group is not particularly limited, but it is preferable that it be one or more electron-withdrawing groups selected from the group consisting of chloro, fluoro, trifluoromethyl, carboxyl, and nitro groups. Furthermore, any aromatic compound having an electron-withdrawing group can exist stably under acidic conditions. From the viewpoint of having stronger electrophilicity, it is preferable that the compound contains at least one functional group selected from the group consisting of nitro and trifluoromethyl groups, and more preferably that it contains at least one nitro group. The number of electron-withdrawing groups in the aromatic compound is not particularly limited and may be 1, 2 or more, 10 or less, 6 or less, or 4 or less.

[0089] From the viewpoint of improving solubility in etching solutions, silicon compounds are preferably equipped with hydrophilic groups such as hydroxyl groups.

[0090] The aromatic ring or heteroaromatic ring possessed by the aromatic compound is not particularly limited, and examples include aromatic rings selected from the group consisting of benzene rings, naphthalene rings, anthracene rings, phenalene rings, phenanthrene rings, pyrene rings, fluorene rings, perylene rings, and coronene rings. Among these, benzene rings are preferred from the viewpoint of solubility. The number of aromatic rings possessed by the aromatic compound may be one or two or more.

[0091] The aromatic compound may have substituents other than the electron-withdrawing group described above, as long as the effects of the present invention are obtained. Examples include alkyl groups having 1 to 20 carbon atoms, bromo groups, iodo groups, aldehyde groups, methoxy groups, or ethoxy groups. The number of other substituents on the aromatic compound may be one or two or more.

[0092] Aromatic compounds may or may not have nucleophilic substituents. From the viewpoint of improving solubility, it is preferable to have nucleophilic substituents, but in this case, it is preferable that sufficient electrophilicity is ensured by electron-withdrawing groups.

[0093] If the aromatic ring or heteroaromatic ring of an aromatic compound is a benzene ring, the compound may be represented by the following formula (G).

[0094] [ka]

[0095] In equation (G), R 1 ~R 6 Each of these is independently a hydrogen atom, a chloro group, a fluoro group, a trifluoromethyl group, a carboxyl group, a nitro group, a C1-C20 alkyl group, a bromo group, an iodo group, an aldehyde group, a methoxy group, or an ethoxy group; R 1 ~R 6 At least one of these groups is a chloro group, a fluoro group, a trifluoromethyl group, a carboxyl group, or a nitro group.

[0096] Specific examples of aromatic compounds include, for example, chlorobenzene, dichlorobenzene, trichlorobenzene, fluorobenzene, difluorobenzene, trifluorobenzene, trifluoromethylbenzene, chlorotrifluoromethylbenzene, nitrobenzene, dinitrobenzene, chloronitrobenzene, chlorodinitrobenzene, nitropyridine, hydroxynitropyridine, N8,N8,3-trimethyl-2,8-phenazinediamine, nitrobenzoic acid (e.g., p-nitrobenzoic acid), chlorodinitrobenzoic acid, chloronitrobenzoic acid (e.g., 2-chloro-5-nitrobenzoic acid), dinitrobenzoic acid (e.g., 3,4-dinitrobenzoic acid), trichlorobenzoic acid, trinitrobenzoic acid, or chlorodifluorobenzoic acid. Among these compounds, those for which isomers exist also include the isomers.

[0097] The total concentration of polymerization inhibitors in the etching solution is not particularly limited, but is preferably 0.0001% by mass or more, more preferably 0.001% by mass or more, even more preferably 0.01% by mass or more, particularly preferably 0.03% by mass or more, and also preferably 1% by mass or less, more preferably 0.5% by mass or less, even more preferably 0.3% by mass or less, and particularly preferably 0.1% by mass or less.

[0098] The etching solution is preferably a homogeneous solution in which all components are dissolved. Furthermore, in order to prevent contamination during etching, the number of particles 200 nm or larger in the etching solution is preferably 100 particles / mL or less, and more preferably 50 particles / mL or less. The lower limit is not particularly limited, but may be 0 particles / mL or more. This amount may be, for example, preferably 0 particles / mL to 100 particles / mL or 0 particles / mL to 50 particles / mL. Furthermore, the etching solution may contain gases such as hydrogen or oxygen, depending on the manufacturing process of the etching solution.

[0099] In etching using an etching solution, if the etching solution contains metal, it often affects the workpiece (not limited to the silicon surface being etched), resulting in a decrease in the quality of the final product.

[0100] Therefore, it is preferable that metals are not intentionally added to the etching solution, more preferably that the concentration of metals in the etching solution is below the impurity level, and even more preferably that the etching solution is substantially free of metals (below the detection limit). However, the etching solution may contain metals. The metals referred to here include nonionic metals (particulate metals) such as elemental metals, and metal ions (ionic metals). For example, the total concentration of metals in the etching solution is preferably 1 ppm or less by mass, and more preferably 1 ppb or less. The lower limit is not particularly limited, and the total concentration of metals may be, for example, 0 ppm or more and 1 ppm or less, 0 ppb or more and 1 ppb or less, greater than 0 ppm and 1 ppm or less, or greater than 0 ppb and 1 ppb or less. More specifically, it is preferable that the concentrations of Ag, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, and Zn in the etching solution are all 1 ppm or less by mass, and more preferably 1 ppb or less. The lower limit is not particularly limited, and the concentration of each of the above metals may be, for example, 0 ppm or more and 1 ppm or less, 0 ppb or more and 1 ppb or less by mass, greater than 0 ppm and 1 ppm or less, or greater than 0 ppb and 1 ppb or less. The metals listed here are those that are considered to potentially affect the quality of chemicals used in semiconductor manufacturing. In other words, the quality of the etching solution can be improved by ensuring that the concentration of each metal is within the above-mentioned range.

[0101] The etching solution according to this embodiment can be suitably used as an etching solution in the manufacture of semiconductor devices, which includes an etching step for etching silicon nitride, such as a silicon nitride single crystal film. Note that the silicon nitride single crystal film includes those produced by epitaxial growth.

[0102] <Method for manufacturing etching solution> The method for producing the etching solution is not particularly limited, and may include, for example, a mixing step of mixing one or more acids selected from the group consisting of sulfuric acid and organic acids that do not contain aromatic rings (component A), a boron compound (component B), a silicon compound having at least one Si-O bond and one Si-C bond (component C), and water to obtain a mixture.

[0103] The method of mixing is not particularly limited; it may be a method of mixing by adding each ingredient sequentially, or it may be a method of preparing a composition containing all the ingredients and then mixing them. Specifically, for example, a method is to mix component A, component B, component C, water, and any other component, and dissolve component A, component B, component C, and any other component in water. In this dissolution, it is preferable to dissolve each component uniformly.

[0104] Furthermore, the method for manufacturing the etching solution may further include an aging step in which the mixture is heated (heat-treated). The heating temperature in the aging step is preferably higher than the temperature in the etching step, and the upper limit of the heating temperature can be appropriately determined considering the heat resistance temperature of the components of the equipment used in the aging step. Specifically, it is preferably in the range of 80°C to 200°C, more preferably in the range of 120°C to 200°C, even more preferably in the range of 165°C to 200°C, and particularly preferably in the range of 180°C to 200°C. The heating time in the aging step varies depending on the heating temperature, so it is not possible to determine an optimal range in general, but considering productivity, for example, it is preferably in the range of 1 to 100 hours, more preferably in the range of 3 to 100 hours, even more preferably in the range of 5 to 100 hours, and particularly preferably in the range of 10 to 100 hours. Note that the heating in the aging step may be performed intermittently by repeating heating and cooling. When heating in the aging step is performed intermittently, the heating time is the total time maintained at the heating temperature.

[0105] The total concentration of component C in the mixture is not particularly limited, and the total concentration of component C in the etching solution described above can be applied similarly.

[0106] In the manufacture of etching solutions, it is preferable to have a step in which the raw materials are mixed and dissolved, and then passed through a filter with a size of several nanometers to several tens of nanometers to remove particles. If necessary, the particle removal step may be performed multiple times.

[0107] Furthermore, various known treatments can be applied to obtain the necessary physical properties in semiconductor manufacturing chemicals, such as reducing dissolved oxygen in the etching solution by bubbling with an inert gas like high-purity nitrogen gas.

[0108] For the mixing and dissolving processes described above, and for storing the etching solution, it is preferable to use containers or devices formed or coated with materials known as the inner walls of semiconductor manufacturing chemicals, specifically polyfluoroethylene or high-purity polypropylene, which are materials that do not easily leach contaminants into the etching solution. It is also preferable to clean these containers or devices beforehand.

[0109] <Manufacturing method for semiconductor devices> Another embodiment of the present invention, a method for manufacturing a semiconductor (also simply referred to as "a method for manufacturing a semiconductor device"), is a method for manufacturing a semiconductor device using a substrate containing silicon nitride, This is a method for manufacturing a semiconductor device, which includes an etching step in which a silicon nitride is etched using the etching solution described above.

[0110] The etching solution described above can selectively etch silicon nitride with at least one selected from the group consisting of silicon and silicon oxide. Therefore, the above semiconductor device manufacturing method is a method for manufacturing a semiconductor device using a substrate containing at least one selected from the group consisting of silicon and silicon oxide, and silicon nitride. The method for manufacturing a semiconductor device may include an etching step in which a silicon nitride is selectively etched from at least one selected from the group consisting of silicon and silicon oxide using the etching solution. The following description will explain some examples of the conditions of the embodiment, but will not be limited to these conditions.

[0111] A semiconductor device manufacturing method can be any known method, except that it includes an etching step in which a silicon nitride is selectively etched from at least one selected from the group consisting of silicon and silicon oxide using the etching solution described above. For example, it may include one or more steps selected from the group consisting of a wafer fabrication step, an oxide film formation step, a transistor formation step, a wiring formation step, and a CMP step, and may also include other known steps used in semiconductor manufacturing methods.

[0112] The etching process for selectively etching silicon nitride with at least one material selected from the group consisting of silicon and silicon oxide using the etching solution described above is not particularly limited, but for example, it includes a contact process in which the etching solution is brought into contact with a substrate containing at least one material selected from the group consisting of silicon and silicon oxide, and silicon nitride. By including such a process, an etching solution can be brought into contact with a device structure having a structure in which silicon oxide is used as an insulating film, silicon and silicon-germanium are alternately layered, and silicon nitride is layered on top as a hard mask, thereby selectively removing the silicon nitride from the device structure.

[0113] Furthermore, the etching process is not particularly limited as long as it can selectively etch silicon nitride with at least one selected from the group consisting of silicon and silicon oxide, and may include a substrate holding process for holding the substrate in a horizontal position and a processing liquid supply process for supplying an etching solution to the main surface of the substrate while rotating the substrate around a vertical axis of rotation passing through the center of the substrate, or it may include a substrate holding process for holding a plurality of substrates in an upright position and a process for immersing the substrates in an upright position in an etching solution stored in a processing tank.

[0114] The conditions for the etching process are not particularly limited. For example, the temperature of the etching solution in the etching process can be appropriately determined considering the desired etching rate, the shape and surface condition of the silicon nitride after etching, productivity, the heat resistance temperature of the components of the equipment used for etching, etc. For example, it can be 20 to 200°C, preferably in the range of 50 to 190°C, more preferably in the range of 100 to 190°C, even more preferably in the range of 120 to 185°C, and particularly preferably in the range of 165 to 185°C.

[0115] In the etching process, etching can also be performed under vacuum or reduced pressure while degassing or bubbling with an inert gas. Such operations can suppress or reduce the increase in dissolved oxygen during etching. Alternatively, etching can be performed without bubbling with an inert gas. Failure to perform bubbling increases the dissolved oxygen in the etching solution. When the substrate contains silicon, dissolved oxygen in the etching solution contributes to the oxidation of silicon, which may reduce the etching rate of silicon, but may also increase it. Therefore, if the etching rate of silicon increases due to the effect of dissolved oxygen, that is, if the etching rate of silicon nitride relative to silicon may decrease, bubbling with an inert gas should be performed. Conversely, if the etching rate of silicon is maintained or decreased due to the effect of dissolved oxygen, bubbling with an inert gas should not be performed.

[0116] In the etching process, it is sufficient to simply bring the etching solution into contact with the substrate by immersing it in the etching solution, but an electrochemical etching method that applies a constant potential to the substrate can also be employed.

[0117] As described above, the object to be etched in the etching process is a substrate containing at least one material selected from the group consisting of silicon and silicon oxide, and silicon nitride. Here, the at least one material selected from the group consisting of silicon and silicon oxide is an object that is not to be etched. The forms of silicon, silicon oxide, and silicon nitride are not particularly limited, but may include, for example, a silicon film, a silicon oxide film, or a silicon nitride film, and a silicon nitride single crystal film containing silicon as a substrate is an example. The thickness of the silicon film, etc., is not particularly limited and can be set appropriately depending on the application. The substrate may also include various metal films as non-etchable objects. Examples include alternating layers of silicon and silicon-germanium, silicon-germanium films, silicon oxide films, silicon nitride films, or even silicon, polysilicon, and silicon-germanium films deposited on a silicon single crystal, and structures with patterns formed using these films.

[0118] <Method for processing circuit boards> Another embodiment of the present invention, a method for processing a substrate (also simply referred to as "substrate processing method"), is a method for processing a substrate containing silicon nitride, which includes an etching step of etching the silicon nitride using the etching solution described above. Furthermore, the third embodiment may include steps other than the etching step described above, to the extent that the effects of the present invention can be obtained.

[0119] Since the etching solution described above can selectively etch silicon nitride with at least one selected from the group consisting of silicon and silicon oxide, the above substrate processing method is a substrate processing method comprising at least one selected from the group consisting of silicon and silicon oxide, and silicon nitride. The substrate processing method may include an etching step in which a silicon nitride is selectively etched from at least one selected from the group consisting of silicon and silicon oxide using the etching solution described above. The following description will explain some examples of the conditions of the embodiment, but is not limited to these conditions.

[0120] As an etching step in which a silicon nitride is selectively etched with an etching solution against at least one selected from the group consisting of silicon and silicon oxide, the etching step described in the section on methods for manufacturing silicon devices can be used. Furthermore, the etching process may include, for example, a substrate holding process for holding the substrate in a horizontal position and a processing liquid supply process for supplying an etching solution to the main surface of the substrate while rotating the substrate around a vertical axis of rotation passing through the center of the substrate, or a substrate holding process for holding a plurality of substrates in an upright position and a process for immersing the substrates in an upright position in the etching solution of the first embodiment stored in a processing tank. Furthermore, the substrate described in the section on the method of manufacturing semiconductor devices can be used as the substrate. [Examples]

[0121] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0122] <Ultra pure water> The ultrapure water used for diluting the etching solution in the pH measurement and for preparing the etching solution was produced by purifying water using a Millipore Elix Essential UV5 ultrapure water production system, and then further purifying that water using a Millipore Milli-Q Advantage ultrapure water production system. <Evaluation of etching solutions> The evaluation method for the etching solution in the examples and comparative examples is as follows.

[0123] [Method for measuring the pH of etching solution (10-fold dilution)] First, the etching solution was diluted 10 times by mass using ultrapure water. The pH of the diluted etching solution was measured at a temperature of 24°C using a Horiba F-73 benchtop pH meter and a Horiba 9632-10D pH electrode.

[0124] [Method for calculating etching rate] (SiN) 200 mL of etching solution heated to the specified temperature shown in Table 1 was prepared, and a silicon nitride film (silicon nitride film thickness 104 nm) that had been epitaxially grown on a 2 cm x 1 cm silicon substrate by vacuum CVD (LP-CVD) was immersed in it for 3 minutes. The etching solution was stirred at 700 rpm during etching. Etching rate of silicon nitride film (R SiN The film thickness (nm / min) was calculated by measuring the film thickness of each substrate before and after etching using a spectroscopic ellipsometer (JAWoollam M-2000D), determining the amount of silicon nitride film etched from the difference in film thickness before and after processing, and dividing by the etching time (3 minutes).

[0125] (Si) 200 mL of etching solution heated to the specified temperature shown in Table 1 was prepared, and a silicon nitride film (silicon nitride film thickness 104 nm) that had been epitaxially grown on a 2 cm x 1 cm silicon substrate by vacuum CVD (LP-CVD) was immersed in it for 10 minutes. The etching solution was stirred at 700 rpm during etching. Etching rate of silicon nitride film (R SiN The film thickness (nm / min) was calculated by measuring the film thickness of each substrate before and after etching using a spectroscopic ellipsometer (JAWoollam M-2000D), determining the amount of silicon nitride film etched from the difference in film thickness before and after processing, and dividing by the etching time (10 minutes).

[0126] [Evaluation of Si etching suppression effect] Samples exhibiting a Si etching rate lower than that of Comparative Example 1 were evaluated as having a Si etching suppression effect, while samples exhibiting a Si etching rate equal to or greater than that of Comparative Example 1 were evaluated as not having a Si etching suppression effect. The results are shown in Table 1.

[0127] <Manufacturing of etching solution> [Example 1] Sulfuric acid (manufactured by Fujifilm Wako Pure Chemical Industries, for electronics industry use, 96% by mass aqueous solution, pKa: -3 at 25°C) is diluted with ultrapure water and mixed until the chemical solution is homogeneous, and then fluorine atoms are removed. Boric acid (manufactured by Fujifilm Wako Pure Chemical Industries, reagent grade, powder) was added as a boron compound, and diethoxydimethylsilane (manufactured by TCI), represented by the following formula (E-1), was added as a silicon etching inhibitor. An etching solution was prepared so that the concentration of sulfuric acid was 75% by mass, the concentration of the fluorine-free boron compound (boric acid) was 1.6% by mass, and the concentration of the silicon etching inhibitor was 10 ppm by mass. The solution was then heated at 195°C for 30 minutes, and the etching solution was heated to 185°C (near the boiling point). The resulting etching solution was diluted 10 times by mass with water, and the pH measured at a temperature of 24°C was 1.0 or less. The etching rates of silicon nitride and silicon were evaluated using the obtained etching solution. The evaluation results are shown in Table 1.

[0128] [ka]

[0129] [Example 2] An etching solution was obtained in the same manner as in Example 1, except that the type of silicon etching inhibitor was changed to polydimethylsiloxane (manufactured by Wako Pure Chemical Industries, weight-average molecular weight 237) and the concentration of the silicon etching inhibitor was set to 5 ppm by mass. The obtained etching solution was diluted 10 times by mass with water and the pH measured at a temperature of 24°C was 1.0 or less. The etching rates of silicon-germanium and silicon were evaluated using the obtained etching solution. The evaluation results are shown in Table 1.

[0130] [Example 3] An etching solution was obtained in the same manner as in Example 1, except that the type of silicon etching inhibitor was changed to a cyclic siloxane (manufactured by TCI) represented by the following formula (E-2), and the concentration of the silicon etching inhibitor was set to 10 ppm by mass. The obtained etching solution was diluted 10 times by mass with water, and the pH measured at a temperature of 24°C was 1.0 or less. The etching rates of silicon-germanium and silicon were evaluated using the obtained etching solution. The evaluation results are shown in Table 1.

[0131] [ka]

[0132] [Example 4] An etching solution was obtained in the same manner as in Example 3, except that the concentration of the silicon etching inhibitor was set to 20 ppm by mass. The obtained etching solution was diluted 10 times by mass with water, and the pH measured at a temperature of 24°C was 1.0 or less. The etching rates of silicon-germanium and silicon were evaluated using the obtained etching solution. The evaluation results are shown in Table 1.

[0133] [Example 5] The type of silicon etching inhibitor was changed to triethoxymethylsilane (manufactured by TCI), represented by the following formula (E-3), and the concentration of the silicon etching inhibitor was set to 5 ppm by mass. An etching solution was obtained in the same manner as in Example 1, except for the difference in the preparation method. The obtained etching solution was diluted 10 times by mass with water, and the pH measured at a temperature of 24°C was 1.0 or less. The etching rates of silicon-germanium and silicon were evaluated using the obtained etching solution. The evaluation results are shown in Table 1.

[0134] [ka]

[0135] [Example 6] An etching solution was obtained in the same manner as in Example 1, except that the type of silicon etching inhibitor was changed to 3-aminopropyldimethoxymethylsilane (manufactured by TCI) represented by the following formula (E-4), and the concentration of the silicon etching inhibitor was set to 200 ppm by mass. The obtained etching solution was diluted 10 times by mass with water, and the pH measured at a temperature of 24°C was 1.0 or less. The etching rates of silicon-germanium and silicon were evaluated using the obtained etching solution. The evaluation results are shown in Table 1.

[0136] [ka]

[0137] [Comparative Example 1] An etching solution was obtained in the same manner as in Example 1, except that a silicon etching inhibitor was not used. The obtained etching solution was diluted 10 times by mass with water, and the pH measured at a temperature of 24°C was 1.0 or less. The etching rates of silicon-germanium and silicon were evaluated using the obtained etching solution. The evaluation results are shown in Table 1.

[0138] Furthermore, the etching selectivity ratio is a ratio of etching rates; for example, "SiN / Si" represents "etching rate of SiN / etching rate of Si".

[0139] [Table 1]

[0140] [Example 7] Sulfuric acid (manufactured by Fujifilm Wako Pure Chemical Industries, for electronics industry use, 96% by mass aqueous solution, pKa: -3 at 25°C) is diluted with ultrapure water and mixed until the chemical solution is homogeneous, and then fluorine atoms are removed. Boric acid (manufactured by Fujifilm Wako Pure Chemical Industries, reagent grade, powder) is added as a boron compound, the above-mentioned cyclic siloxane (manufactured by TCI) is added as a silicon etching inhibitor, and 4-chloro-3,5-dinitrobenzoic acid (manufactured by TCI) is added as a polymerization inhibitor, with a sulfuric acid concentration of 75% by mass and fluorine An etching solution was prepared with a concentration of 1.6% by mass of a boron compound (boric acid) that does not contain atoms, a concentration of 10 ppm by mass of a silicon etching inhibitor, and a concentration of 500 ppm by mass of a polymerization inhibitor. The solution was then heated at 195°C for 30 minutes, and the etching solution was heated to 185°C (near the boiling point). The resulting etching solution was diluted 10 times by mass with water, and the pH measured at a temperature of 24°C was 1.0 or less. The etching inhibitory effect was evaluated using the obtained etching solution. The evaluation results are shown in Table 2.

[0141] [Example 8] An etching solution was obtained in the same manner as in Example 7, except that the type of polymerization inhibitor was changed to m-nitrobenzoic acid (manufactured by TCI) and the concentration of the polymerization inhibitor was set to 1200 ppm by mass. The obtained etching solution was diluted 10 times by mass with water, and the pH measured at a temperature of 24°C was 1.0 or less. The etching inhibitory effect was evaluated using the obtained etching solution. The evaluation results are shown in Table 2.

[0142] [Example 9] An etching solution was obtained in the same manner as in Example 7, except that the type of polymerization inhibitor was changed to 2,4-dinitrobenzoic acid (manufactured by TCI) and the concentration of the polymerization inhibitor was set to 1200 ppm by mass. The obtained etching solution was diluted 10 times by mass with water, and the pH measured at a temperature of 24°C was 1.0 or less. The etching inhibitory effect was evaluated using the obtained etching solution. The evaluation results are shown in Table 2.

[0143] [Example 10] An etching solution was obtained in the same manner as in Example 7, except that the type of silicon etching inhibitor was changed to diethoxydimethylsilane, the concentration of the silicon etching inhibitor was changed to 60 ppm by mass, and the concentration of the polymerization inhibitor was changed to 500 ppm by mass. The obtained etching solution was diluted 10 times by mass with water, and the pH measured at a temperature of 24°C was 1.0 or less. The etching inhibitory effect was evaluated using the obtained etching solution. The evaluation results are shown in Table 2.

[0144] [Table 2]

[0145] Tables 1 and 2 show that silicon nitride can be efficiently etched from silicon using the silicon nitride etching solution according to one embodiment of the present invention. Furthermore, it can be seen that the etching of silicon can be suppressed by using the silicon etching inhibitor according to one embodiment of the present invention. [Industrial applicability]

[0146] According to the present invention, it is possible to provide an etching solution for silicon nitride that can efficiently etch silicon nitride, and an etching inhibitor that can efficiently suppress the etching of materials such as silicon or silicon oxide.

Claims

1. An etching solution for silicon nitride comprising one or more acids selected from the group consisting of sulfuric acid and organic acids that do not contain aromatic rings (component A), a boron compound (component B), a silicon compound having at least one Si-O bond and one Si-C bond (component C), and water.

2. The silicon according to claim 1, wherein the pKa of the acid at 25°C is -5 or more and 2 or less. Nitride etching solution.

3. The etching solution for silicon nitride according to claim 1, wherein at least one of the boiling point and decomposition temperature of the acid at 1 atmosphere is 150°C or higher and 400°C or lower.

4. The etching solution for silicon nitride according to claim 1, wherein the aromatic ring-free organic acid is one or more aromatic ring-free organic acids selected from sulfonic acid compounds and carboxylic acid compounds.

5. Furthermore, the etching solution for silicon nitride according to claim 1, comprising an aromatic ring compound (component G) having an electron-withdrawing group.

6. The etching solution for silicon nitride according to claim 1, wherein the organosilicon compound (component C) is represented by any one of the following formulas (1) to (3). 【Chemistry 1】 (In equations (1) to (3) above, R １ ~R ３ Each independently represents a hydrogen atom, an optionally substituted C5-C12 aryl group, an optionally substituted C2-C10 linear alkenyl group, an optionally substituted C3-C10 branched alkenyl group, an optionally substituted C2-C10 linear alkynyl group, an optionally substituted C2-C10 linear alkoxy group, an epoxy group, a styryl group, a metasyloxy group, an acyloxy group, an amino group, a ureido group, an isocyanate group, an isocyanurate group, or a mercapto group; R １ ~R ３ One or more of these independently have a hydrophobic group capable of forming a Si-C bond with the Si represented in formula (1); R ４ This includes a hydrogen atom, an aryl group having 5 to 12 carbon atoms which may have substituents, and a linear alkenyl group having 2 to 10 carbon atoms which may have substituents. Represents a branched alkenyl group having 3 to 10 carbon atoms, which may have substituents; a linear alkynyl group having 2 to 10 carbon atoms, which may have substituents; an epoxy group; a styryl group; a metasyloxy group; an acyloxy group; an amino group; a ureido group; an isocyanate group; an isocyanurate group; or a mercapto group; R １１ to R １６ and R ２１ to R ２６ each independently represents a hydrogen atom, a linear alkyl group having 1 to 10 carbon atoms which may have a substituent, a branched alkyl group having 3 to 10 carbon atoms which may have a substituent, a cyclic alkyl group having 3 to 10 carbon atoms which may have a substituent, an aryl group having 5 to 12 carbon atoms which may have a substituent, a linear alkenyl group having 2 to 10 carbon atoms which may have a substituent, a branched alkenyl group having 3 to 10 carbon atoms which may have a substituent, a linear alkynyl group having 2 to 10 carbon atoms which may have a substituent, a linear alkoxy group having 2 to 10 carbon atoms which may have a substituent, an epoxy group, a styryl group, a methacyloxy group, an acyloxy group, an amino group, a ureido group, an isocyanate group, an isocyanurate group, or a mercapto group; R １１ to R １６ any one or more of them each independently has a hydrophobic group capable of forming a Si—C bond with Si represented in formula (2); R ２１ to R ２６ any one or more of them each independently has a hydrophobic group capable of forming a Si—C bond with Si represented in formula (3); n １１ is an integer from 1 to 10; n ２１ is an integer from 1 to 10.)

7. The etching solution for silicon nitride according to claim 1, wherein the total concentration of the organosilicon compounds is 0.1 ppm by mass or more and less than 1,000 ppm by mass.

8. A method for processing a substrate containing silicon nitride, A method for processing a substrate, comprising an etching step of etching a silicon nitride using a silicon nitride etching solution according to any one of claims 1 to 7.

9. The substrate further comprises at least one selected from the group consisting of silicon and silicon oxide, The substrate processing method according to claim 8, wherein the etching step is a step of selectively etching a silicon nitride with at least one selected from the group consisting of silicon and silicon oxide using the etching solution.

10. A method for manufacturing a semiconductor device using a substrate containing silicon nitride, A method for manufacturing a semiconductor device, comprising an etching step of etching a silicon nitride using a silicon nitride etching solution according to any one of claims 1 to 7.

11. The substrate further comprises at least one selected from the group consisting of silicon and silicon oxide, The method for manufacturing a semiconductor device according to claim 10, wherein the etching step is a step of selectively etching a silicon nitride with at least one selected from the group consisting of silicon and silicon oxide using the etching solution.

12. A silicon etching inhibitor comprising an organosilicon compound having at least one Si-O bond and at least one Si-C bond.

13. A silicon etching inhibitor comprising an organosilicon compound having a structure represented by any of the following formulas (1) to (3). 【Chemistry 2】 (In equations (1) to (3) above, R １ ~R ３ Each independently represents a hydrogen atom, an optionally substituted C5-C12 aryl group, an optionally substituted C2-C10 linear alkenyl group, an optionally substituted C3-C10 branched alkenyl group, an optionally substituted C2-C10 linear alkynyl group, an optionally substituted C2-C10 linear alkoxy group, an epoxy group, a styryl group, a metasyloxy group, an acyloxy group, an amino group, a ureido group, an isocyanate group, an isocyanurate group, or a mercapto group; R １ ~R ３ One or more of these independently have a hydrophobic group capable of forming a Si-C bond with the Si represented in formula (1); R ４ This represents a hydrogen atom, an optionally substituted C5-C12 aryl group, an optionally substituted C2-C10 linear alkenyl group, an optionally substituted C3-C10 branched alkenyl group, an optionally substituted C2-C10 linear alkynyl group, an epoxy group, a styryl group, a metasyloxy group, an acyloxy group, an amino group, a ureido group, an isocyanate group, an isocyanurate group, or a mercapto group; R １１ ~R １６ and R ２１ ~R ２６ Each independently represents a hydrogen atom, a C1-C10 linear alkyl group which may have substituents, a C3-C10 branched alkyl group which may have substituents, a C3-C10 cyclic alkyl group which may have substituents, an aryl group which may have substituents, a C5-C12 linear alkenyl group which may have substituents, a C2-C10 linear alkenyl group which may have substituents, a C3-C10 branched alkenyl group which may have substituents, a C2-C10 linear alkynyl group which may have substituents, a C2-C10 linear alkoxy group which may have substituents, an epoxy group, a styryl group, a metasyloxy group, an acyloxy group, an amino group, a ureido group, an isocyanate group, an isocyanurate group, or a mercapto group; R １１ ~R １６ One or more of these independently have a hydrophobic group capable of forming a Si-C bond with the Si represented in formula (2); R ２１ ~R ２６ One or more of these independently have a hydrophobic group capable of forming a Si-C bond with the Si represented in formula (3); n １１ n is an integer between 1 and 10; ２１ (This is an integer between 1 and 10.)

14. A mixing step is included in which one or more acids selected from the group consisting of sulfuric acid and organic acids that do not contain aromatic rings (component A), a boron compound (component B), a silicon compound having at least one Si-O bond and one Si-C bond (component C), and water are mixed to obtain a mixture of silicon A method for manufacturing a nitride etching solution.

15. The method for producing a silicon nitride etching solution according to claim 14, wherein the total concentration of component C in the mixture is 0.1 ppm by mass or more and less than 1,000 ppm by mass.

16. A method for producing a silicon nitride etching solution according to claim 14 or 15, further comprising a heat treatment of heating the mixture to 80 to 200°C.

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