Silicon etching solution, method for processing silicon substrate, and method for manufacturing semiconductor device

Abstract

This silicon etching solution contains an alkaline organic compound and water, and further contains an amino acid having no cyclic structure, wherein the content of the amino acid is 100 ppm by mass or more.

Description

Silicon etching solution, silicon substrate processing method, and semiconductor device manufacturing method

[0001] This disclosure relates to a silicon etching solution. More specifically, it relates to a silicon etching solution (hereinafter also referred to as "etching solution") used in the manufacturing of semiconductor devices, such as when etching silicon (Si) for microfabrication, or when removing silicon that is no longer needed after it has served its purpose as a dummy or carrier substrate. In particular, it relates to an etching solution that is useful for selectively etching silicon without etching silicon germanium.

[0002] This disclosure also relates to a substrate processing method using the etching solution. The substrate includes semiconductor wafers or silicon substrates. Furthermore, this disclosure relates to a method for manufacturing semiconductor devices using the etching solution.

[0003] In the manufacturing process of semiconductor devices, silicon etching is used in various steps. In recent years, semiconductor devices such as logic devices and memory cells have progressed to three-dimensional structures, and the requirements for smoothness of the wafer surface after etching, etching accuracy, and etching selectivity with other materials have become stricter. Regarding etching selectivity with other materials, silicon germanium is used as a material for fabricating nanometer-order fine structures in GAA (Gate All Around) logic devices. It is also used as an etching stop layer on the wafer side to be removed after bonding in various device fabrication processes, including wafer bonding for purposes such as electrode formation on the back side of the device and three-dimensional device fabrication. In all applications, a method is required to selectively remove silicon from silicon germanium within a series of processes. As a difference in requirements depending on the application, when fine processing is required, such as the fabrication of GAA (Gate All Around) structures, it is important to be able to control the amount of etching with high precision, so a high silicon etching rate is not required, and etching selectivity between silicon and silicon germanium becomes important. On the other hand, in various device manufacturing processes, including wafer bonding, when unwanted silicon is removed after bonding, a large amount of silicon is removed, requiring not only good etching selectivity between silicon and silicon-germanium, but also a high silicon etching rate.

[0004] In silicon etching solutions consisting of alkaline aqueous solutions, several etching solutions have been proposed that selectively remove silicon from silicon germanium by adding various additives to improve various properties or to introduce new properties, in addition to alkaline compounds and water. For example, one such additive is a reducing compound such as a reducing sugar, which reduces the dissolved oxygen in the etching solution (see, for example, Patent Document 1). In these techniques, the reducing sugar improves the etching rate of silicon and improves the etching selectivity of silicon to silicon germanium. Another common method, besides adding additives to reduce dissolved oxygen in the etching solution, is to bubble the etching solution with an inert gas such as nitrogen.

[0005] International Publication No. 2022 / 172907

[0006] As described above, the etching selectivity of silicon to silicon germanium can be improved by reducing the dissolved oxygen in a silicon etching solution consisting of an alkaline aqueous solution and performing etching. However, the present inventors' investigation revealed that the pH of an alkaline silicon etching solution with added reducing sugars rapidly decreases during storage, and as a result, the etching rate of silicon also decreases. Normally, silicon etching solutions are expected to be used repeatedly at the processing temperature. Therefore, if the etching rate changes over time, it becomes difficult to determine the process time in the manufacturing process, which poses a significant problem. Furthermore, in the method of reducing dissolved oxygen in the etching solution by bubbling with an inert gas, there is a problem in that oxygen from the atmosphere is easily redissolved between the time the dissolved oxygen in the etching solution is reduced by bubbling and the etching process is performed, or during the etching process, making it difficult to control the dissolved oxygen concentration.

[0007] Therefore, the present disclosure aims to provide an etching solution that exhibits high etching selectivity for silicon relative to silicon germanium and a high etching rate for silicon, regardless of the presence or absence of dissolved oxygen in the etching solution, for surface processing when manufacturing various semiconductor devices, particularly for various silicon composite semiconductor devices containing silicon germanium.

[0008] In light of the above issues, the Disclosing Parties conducted thorough research. As a result, they found that by adding 100 ppm or more of amino acids without a cyclic structure to an aqueous solution of an alkaline organic compound, the etching selectivity of silicon to silicon germanium can be increased regardless of the presence or absence of dissolved oxygen in the etching solution, and the etching rate can also be increased, leading to the completion of this disclosure.

[0009] That is, the structure of this disclosure is as follows: Item 1 A silicon etching solution comprising an alkaline organic compound and water, further comprising an amino acid that does not have a cyclic structure, wherein the content of the amino acid is 100 ppm by mass or more. Item 2 The silicon etching solution according to Item 1, wherein the amino acid that does not have a cyclic structure is an amino acid represented by the following formula (1); In formula (1), R １ R is a hydrocarbon group having 1 to 10 carbon atoms, which may have a hydrogen atom or substituents. ２is a hydrocarbon group having 1 to 10 carbon atoms, which may have a hydrogen atom or a substituent. Item 3 The silicon etching solution according to item 1 or 2, wherein the pH of the silicon etching solution is 9.5 or more and 13.0 or less at 23°C. Item 4 The silicon etching solution according to any one of items 1 to 3, wherein the alkaline organic compound is an amine compound or a quaternary ammonium hydroxide. Item 5 The silicon etching solution according to any one of items 1 to 4, wherein the amino acid is glycine or sarcosine. Item 6 The silicon etching solution according to any one of items 1 to 5, wherein the concentrations of Ag, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, and Zn are all 10 ppb by mass or less. Item 7 A method for processing a silicon substrate, wherein the silicon substrate comprises at least one silicon material selected from the group consisting of a silicon wafer, a silicon single crystal film, a polysilicon film, and an amorphous silicon film, and comprises etching the silicon material using a silicon etching solution according to any one of Items 1 to 6. Item 8 A method for processing a silicon substrate according to Item 7, wherein the silicon etching solution is a silicon etching solution after bubbling with an inert gas. Item 9 A method for processing a silicon wafer or substrate, comprising selectively etching silicon relative to silicon germanium in a silicon wafer containing a silicon germanium film, and / or selectively etching at least one type selected from the group consisting of a silicon single crystal film, a polysilicon film, and an amorphous silicon film relative to silicon germanium in a substrate containing a silicon germanium film, using a silicon etching solution according to any one of Items 1 to 6. Item 10 A method for manufacturing a semiconductor device having a silicon substrate, wherein the silicon substrate comprises at least one silicon material selected from the group consisting of a silicon wafer, a silicon single crystal film, a polysilicon film, and an amorphous silicon film, and the method comprises etching the silicon material using a silicon etching solution according to any one of items 1 to 6.A method for manufacturing a semiconductor device, comprising: selectively etching silicon with respect to silicon germanium in a silicon wafer containing a silicon germanium film using a silicon etching solution described in any of items 1 to 6; and / or selectively etching at least one selected from the group consisting of a silicon single crystal film, a polysilicon film, and an amorphous silicon film with respect to a silicon germanium film in a substrate containing a silicon germanium film.

[0010] According to this disclosure, it is possible to provide an etching solution that exhibits high etching selectivity for silicon relative to silicon germanium, and a high etching rate for silicon, regardless of the presence or absence of dissolved oxygen in the etching solution. Therefore, this disclosure can be applied even when not only etching selectivity between silicon and silicon germanium is required, but also a high silicon etching rate, and a decrease in etching rate due to changes in the chemical solution over time is unacceptable.

[0011] The following provides a detailed explanation of this disclosure. The following explanation is an example (representative example) of this disclosure, and the disclosure is not limited to this example. Furthermore, this disclosure may be modified and implemented at any time without departing from its essence.

[0012] In this specification, a numerical range expressed using "~" means "greater than or equal to the stated lower limit and less than or equal to the stated upper limit," and refers to a range that includes the numbers written before and after "~" as the lower limit and upper limit, respectively. Furthermore, when a numerical range is described in steps, the upper and lower limits of each numerical range can be combined in any way. In addition, in this specification, the expression "A or B" can be read as "at least one selected from the group consisting of A and B."

[0013] <Silicon Etching Solution> A silicon etching solution according to one embodiment of the present disclosure (hereinafter also simply referred to as "etching solution") can be used for etching silicon (crystalline silicon or amorphous silicon) in the manufacture of semiconductor chips, etc. Although silicon etching can be performed under acidic conditions or alkaline conditions, the etching solution according to the present embodiment may be an alkaline aqueous solution (pH greater than 7) containing an alkaline organic compound, and can be used for etching under alkaline conditions.

[0014] [Alkaline Organic Compounds] The etching solution contains alkaline organic compounds. The alkaline organic compound is not particularly limited as long as it is an organic compound that exhibits alkalinity (an organic compound that dissolves in water and exhibits alkalinity). The alkaline organic compound is preferably a variety of primary to tertiary amine compounds or quaternary ammonium hydroxide, and more preferably an amine compound containing at least one primary amino group or quaternary ammonium hydroxide, as these tend to increase the etching rate of silicon. These substances may exist in the etching solution in the form of ammonium hydroxide, etc., or as ions. Note that the compound represented by formula (1) described later (also referred to as compound (1)) is also R １ Ya R ２ Depending on the embodiment, it may become an alkaline organic compound, but in this specification, the compound represented by formula (1) is treated as a compound represented by formula (1), not an alkaline organic compound.

[0015] Specific examples of amine compounds containing at least one primary amino group include, as primary or secondary amines, ethylenediamine, 1,3-diaminopropane, 1,2-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, N,N-bis One or more substances selected from the group consisting of (3-aminopropyl)ethylenediamine, 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)ethanolamine, N-(2-aminoethyl)propanolamine, N-(2-hydroxypropyl)ethylenediamine, azetidine, pyrrolidine, piperidine, hexamethyleneimine, pentamethyleneimine, and octamethyleneimine may be used.

[0016] 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.

[0017] Amine compounds contain at least one primary amino group, and the fewer carbon atoms the compound contains, the higher the silicon etching rate tends to be. Among the above, one or more compounds selected from the group consisting of ethylenediamine, 1,3-diaminopropane, 1,2-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 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)ethanolamine, and N-(2-aminoethyl)propanolamine can be listed as being more preferable in terms of silicon etching rate. More preferably, one or more can be selected from the group consisting of ethylenediamine, 1,3-diaminopropane, 1,2-diaminopropane, 1,4-diaminobutane, diethylenetriamine, 2-(2-aminoethoxy)ethanol, and N-(2-aminoethyl)ethanolamine. Among the above, one or more can be selected from the group consisting of ethylenediamine, 1,3-diaminopropane, 1,2-diaminopropane, 1,4-diaminobutane, and diethylenetriamine, which contain multiple primary amino groups. These may be used individually or in combination of two or more.

[0018] Specific examples of quaternary ammonium hydroxides include tetramethylammonium hydroxide (TMAH), ethyltrimethylammonium hydroxide (ETMAH), propyltrimethylammonium hydroxide (PTMAH), butyltrimethylammonium hydroxide (BTMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, trimethyl-2-hydroxyethylammonium hydroxide (choline hydroxide), dimethylbis(2-hydroxyethyl)ammonium hydroxide, methyltris(2-hydroxyethyl)ammonium hydroxide, phenyltrimethylammonium hydroxide, or benzyltrimethylammonium hydroxide. These may be used individually or in combination of two or more.

[0019] Quaternary ammonium hydroxides tend to have a higher etching rate as their molecular size decreases. Among the above, quaternary ammonium hydroxides with a total number of carbon atoms of 8 or less are preferred, and quaternary ammonium hydroxides with a total number of carbon atoms of 6 or less (e.g., TMAH or ETMAH) are particularly preferred. On the other hand, quaternary ammonium hydroxides with a total number of carbon atoms of 5 or more are preferred because they have lower toxicity compared to TMAH (e.g., ETMAH or PTMAH).

[0020] In etching solutions, these quaternary ammonium hydroxides typically dissociate and exist as hydroxide ions and quaternary ammonium ions. In other words, etching solutions are usually liquids containing hydroxide ions (which are alkaline) and their counterions (quaternary ammonium ions).

[0021] If an alkaline organic compound is included, the etching solution will usually become alkaline and may possess etching capabilities. Therefore, the content of the alkaline organic compound may be adjusted as appropriate according to the desired pH.

[0022] The content of alkaline organic compounds in the etching solution is usually 0.01% by mass or more, although this depends on the type and content of other components. The higher the content of the alkaline organic compounds, the higher the alkalinity, and it is preferably 0.05% by mass or more, more preferably 0.10% by mass or more, and particularly preferably 0.20% by mass or more. Furthermore, the content of the alkaline organic compounds may be 20.00% by mass or less, 15.00% by mass or less, and sufficient performance can be obtained even with 10.00% by mass or less. For this reason, the content of the alkaline organic compounds is preferably 0.05% by mass or more and 20.00% by mass or less, more preferably 0.10% by mass or more and 15.00% by mass or less, even more preferably 0.20% by mass or more and 10.00% by mass or less, particularly preferably 0.40% by mass or more and 8.00% by mass or less, and especially preferably 1.00% by mass or more and 5.00% by mass or less.

[0023] While the content of alkaline organic compounds can be calculated from pH when it is low, the error can become large when it is high. Therefore, it is more accurate and preferable to measure the countercation content using an ion chromatograph or similar method and then calculate the content from there.

[0024] [Amino acid having no cyclic structure] The silicon etching solution according to the present embodiment contains 100 mass ppm or more of an amino acid having no cyclic structure. More specifically, the amino acid is preferably a compound represented by formula (1) (also referred to as compound (1)). Hereinafter, a case where the amino acid having no cyclic structure is compound (1) will be described as an example; however, the amino acid is not limited thereto as long as it has no cyclic structure, and "compound (1)" may be appropriately read as "amino acid having no cyclic structure". In the present disclosure, the term "amino acid" means a compound having one or more carboxy groups and one or more amino groups in the molecule, respectively. When an amino acid has optical isomers, it may be an L-isomer, a D-isomer, or a racemate. When the silicon etching solution contains compound (1), the etching selectivity of silicon relative to silicon germanium is improved compared to a case where the etching solution does not contain compound (1). Compound (1) may be present in the state of the compound represented by formula (1) in the etching solution, or may be present as an ion thereof (for example, an ion obtained by elimination of a hydrogen atom from a carboxy group, or an ion obtained by addition of a proton to a nitrogen atom), or may be present in the state of a zwitterion in which both the carboxy group and the nitrogen atom are ionized.

[0025]

[0026] In formula (1), R １ is a hydrogen atom or an optionally substituted hydrocarbon group having 1 to 10 carbon atoms. In addition, R ２ is a hydrogen atom or an optionally substituted hydrocarbon group having 1 to 10 carbon atoms.

[0027] The present inventors have found that a silicon etching solution containing 100 mass ppm or more of an amino acid having no cyclic structure has both high etching selectivity of silicon to silicon germanium and a high silicon etching rate, and can achieve both of these properties. The following mechanism is presumed as the reason therefor. That is, in compound (1), when a carboxy group has an ionized hydrogen atom or an ionized carboxy group, the counter cation, and when an amino group has an ionized hydrogen atom or an ionized amino group, the nitrogen atom, sandwich the terminal hydrogen of hydrogen-terminated silicon, whereby the terminal hydrogen becomes hydride (H － ) and is easily eliminated. As a result, it is presumed that the nucleophilic substitution reaction of hydrogen-terminated silicon is promoted, and the elimination of silicon is promoted. On the other hand, in silicon germanium, the electronegativity of germanium atoms, which are constituent elements, is higher than that of silicon atoms, and the degree of δ ＋ of silicon atoms in a hydrogen-terminated silicon state is larger than that in the case of single silicon. Therefore, the susceptibility to nucleophilic substitution reaction of hydrogen-terminated silicon, which greatly affects the etching rate for single silicon, is considered to have a relatively small effect in the case of silicon germanium. As a result, it is considered that addition of the above compound (1) can improve the etching selectivity ratio of silicon to silicon germanium and promote the etching of silicon. Furthermore, when compound (1) has a cyclic structure, the cyclic structure moiety has high hydrophobicity, so it adsorbs to the similarly hydrophobic silicon surface and inhibits silicon etching, which may reduce the silicon etching rate and the etching selectivity ratio of silicon to silicon germanium. However, it is considered that since compound (1) does not have a cyclic structure, these reductions can be suppressed.

[0028] R in formula (1) １ is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms. Further, the hydrocarbon group having 1 to 10 carbon atoms may or may not further have a substituent.

[0029] R in formula (1) １From the viewpoint of the defoaming property of the chemical solution, a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms is preferable, a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms is more preferable, and a hydrogen atom or a hydrocarbon group having 1 carbon atom (methyl group) is even more preferable. A cationized amino group (-N + HR １ ) can increase the pKa and make it easier to adjust the pH of the etching solution to a suitable range, so a hydrocarbon group having 1 carbon atom (methyl group) is particularly preferable.

[0030] R １ The substituent that may be possessed by is not particularly limited as long as the effects of the present disclosure can be obtained, and examples thereof include a halogen atom, a hydroxy group, a carboxy group, an acetyl group, a silyl group, a boryl group, a nitrile group, a thio group, a seleno group, or a hydrocarbon group.

[0031] R １ The type of halogen atom in the substituent that may be possessed by is not particularly limited, and may be fluorine, chlorine, bromine, or iodine; however, as described later, since it is preferable that no component that promotes etching of silicon dioxide (SiO ２ ) is not contained, it is preferably other than a fluorine atom, that is, chlorine, bromine, iodine, or the like.

[0032] R １ The hydrocarbon group in the substituent that may be possessed by is preferably an alkyl group. The number of carbon atoms of the hydrocarbon group is not particularly limited, but from the viewpoint of improving the etching rate by reducing steric hindrance, it is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1. The hydrocarbon group may be linear or branched, and is preferably linear.

[0033] R in formula (1) ２ is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms. The hydrocarbon group having 1 to 10 carbon atoms may or may not further have a substituent.

[0034] R in formula (1) ２From the viewpoint of reducing steric hindrance, hydrogen atoms or hydrocarbon groups having 1 to 5 carbon atoms are preferred, hydrogen atoms or hydrocarbon groups having 1 to 3 carbon atoms are more preferred, hydrogen atoms or hydrocarbon groups having 1 carbon atom (methyl group) are even more preferred, and hydrogen atoms are particularly preferred.

[0035] R ２ The substituents that may be present are not particularly limited as long as the effects of this disclosure are obtained, and include halogen atoms, hydroxyl groups, carboxyl groups, acetyl groups, silyl groups, boryl groups, nitrile groups, thio groups, seleno groups, or hydrocarbon groups.

[0036] R ２ The types of halogen atoms in the substituents that can be present are not particularly limited and may be fluorine, chlorine, bromine, or iodine, but as will be described later, under alkaline conditions, silicon dioxide (SiO ２ Since it is preferable that the halogen atom does not contain any components that promote etching, it is preferable that the halogen atom is chlorine, bromine, or iodine, and not a fluorine atom.

[0037] R ２ The hydrocarbon group in the substituent that may be present is preferably an alkyl group. Furthermore, the number of carbon atoms in the hydrocarbon group is not particularly limited, but from the viewpoint of improving the etching rate by reducing steric hindrance, it is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1. Furthermore, the hydrocarbon group may be linear or branched, but it is preferably linear.

[0038] Specific examples of the compound (1) include glycine, N-methylglycine (sarcosine), N-ethylglycine, N-propylglycine, N-isopropylglycine, N-butylglycine, N-isobutylglycine, N-pentylglycine, N-isopentylglycine, N-hexylglycine, N-isohexylglycine, N-heptylglycine, N-isoheptylglycine, N-octylglycine, N-isooctylglycine, N-nonylglycine, N-isononylglycine, N-decylglycine, N-isodecylglycine, L-alanine, N-methylglycine N-L-Alanine, N-Propyl-L-Alanine, N-Isopropyl-L-Alanine, N-Butyl-L-Alanine, N-Isobutyl-L-Alanine, N-Pentyl-L-Alanine, N-Isopentyl-L-Alanine, N-Hexyl-L-Alanine, N-Isohexyl-L-Alanine, N-Heptyl-L-Alanine, N-Isoheptyl-L-Alanine, N-Octyl-L-Alanine, N-Isooctyl-L-Alanine, N-Nonyl-L-Alanine, N-Isononyl-L-Alanine, N-Decyl-L-Alanine, N-Isodecyl-L-Alanine, Valine N-methylvaline, N-propylvaline, N-isopropylvaline, N-butylvaline, N-isobutylvaline, N-pentylvaline, N-isopentylvaline, N-hexylvaline, N-isohexylvaline, N-heptylvaline, N-isoheptylvaline, N-octylvaline, N-isooctylvaline, N-nonylvaline, N-isononylvaline, N-decylvaline, N-isodecylvaline, leucine, N-methylleucine, N-propylleucine, N-isopropylleucine, N-butylleucine, N-isobutylleucine, N-pentyl Leucine, N-isopentylleucine, N-hexylleucine, N-isohexylleucine, N-heptylleucine, N-isoheptylleucine, N-octylleucine, N-isooctylleucine, N-nonylleucine, N-isononylleucine, N-decylleucine, N-isodecylleucine, isoleucine, N-methylisoleucine, N-propylisoleucine, N-isopropylisoleucine, N-butylisoleucine, N-isobutylisoleucine, N-pentylisoleucine, N-isopentylisoleucine, N-hexylisoleucine,Examples include N-isohexylisoleucine, N-heptylisoleucine, N-isoheptylisoleucine, N-octylisoleucine, N-isooctylisoleucine, N-nonylisoleucine, N-isononylisoleucine, N-decylisoleucine, or N-isodecylisoleucine. These may be used individually or in combination of two or more.

[0039] From the viewpoint of improving etching rate by reducing the defoaming properties and steric hindrance of the chemical solution, R １ R is a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms. ２ Glycine, N-methylglycine (sarcosine), N-ethylglycine, N-propylglycine, N-isopropylglycine, N-butylglycine, N-isobutylglycine, N-pentylglycine, N-isopentylglycine, L-alanine, N-methyl-L-alanine, N-propyl-L-alanine, N-isopropyl-L-alanine, N-butyl-L-alanine, N-isobutyl-L-alanine, N-pentyl-L-alanine, or N-isopentyl-L-alanine is more preferably R １ R is a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms. ２ Glycine, N-methylglycine (sarcosine), N-ethylglycine, N-propylglycine, N-isopropylglycine, L-alanine, N-methyl-L-alanine, N-propyl-L-alanine, or N-isopropyl-L-alanine are more preferably, where R is a hydrogen atom or a C1 hydrocarbon group (methyl group). １ is a hydrogen atom or a hydrocarbon group having 1 carbon atom, R ２ Glycine, or N-methylglycine (sarcosine), L-alanine, and N-methyl-L-alanine are particularly preferred, where the hydrogen atom or carbon-1 hydrocarbon group is used.

[0040] The content of compound (1) in the etching solution is not particularly limited as long as it is 100 ppm by mass or more (0.01% by mass or more) from the viewpoint of improving the etching selectivity ratio of silicon to silicon germanium. However, from the viewpoint of further improving the etching selectivity ratio, it is preferably 0.01 to 20.00% by mass, more preferably 0.10 to 10.00% by mass, even more preferably 0.50 to 10.00% by mass, and particularly preferably 0.50 to 7.00% by mass. The content of each component such as the organic alkali compound and compound (1) in the etching solution can be appropriately measured by known means such as titration, high-performance liquid chromatography, and nuclear magnetic resonance (NMR) analysis.

[0041] The ratio of the molar mass of compound (1) to the alkaline organic compound in the etching solution (compound (1) / alkaline organic compound) is determined by the pKa of the alkaline organic compound and compound (1) used and the desired pH, and is therefore not particularly limited. However, as a practical range, at 23°C, it is preferably 0.001 to 5.00, more preferably 0.10 to 4.00, even more preferably 0.30 to 3.00, and particularly preferably 0.80 to 2.00.

[0042] Compound (1) can be synthesized by known methods or a combination of known methods, but commercially available products may also be used. If the concentration of contained metal impurities (Ag, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, and Zn) exceeds the preferred range described later, the concentration of metal impurities can be reduced by purification. The purification method is not particularly limited, but for example, methods such as purification by recrystallization or purification with a cation exchange resin can be used. Purification with a cation exchange resin is preferable from the viewpoint of preventing contamination by impurities in handling and post-purification processes, as the prepared etching solution can be purified and then filled into storage containers or transport containers.

[0043] Compound (1) preferably contains Ag, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, and Zn, all of which are preferably 1 ppm by mass or less, more preferably the content of each metal is 200 ppb by mass or less, even more preferably 100 ppb by mass or less, and particularly preferably 20 ppb by mass or less. The metals listed here are those that are considered to affect the quality of chemicals used in semiconductor manufacturing.

[0044] [Water] The etching solution according to this embodiment contains water as an essential component. Etching will not proceed if the etching solution does not contain water. The amount of water in the etching solution is not particularly limited and may be the amount found in a typical etching solution. Depending on the type and amount of other components, 30.0% by mass or more is preferred, 50.0% by mass or more is more preferred, 60.0% by mass or more is even more preferred, and 75.0% by mass or more is particularly preferred. Furthermore, there is no particular upper limit as long as other components can be contained in the desired amount, but usually 99.5% by mass or less is sufficient, and sufficient effects can be obtained even at 99.0% by mass or less.

[0045] [Other Substances] The silicon etching solution according to this embodiment may contain substances other than the alkaline organic compound, compound (1), and water described above (hereinafter also referred to as "other substances"), to the extent that the effects of this disclosure are obtained. Examples of other substances include substances that can be contained in a general silicon etching solution, such as metal corrosion inhibitors, organic solvents, catalysts, complexing agents, chelating agents, surfactants, defoaming agents, pH adjusters, stabilizers, solubilizers, or precipitation inhibitors. Even if a substance falls under these categories, if it falls under the alkaline organic compound or compound (1) described above, it will be treated as the alkaline organic compound or compound (1) described above. When other substances are included in the etching solution, even if the substance reduces the etching selectivity ratio of silicon to silicon germanium, if it is necessary to include it for some purpose, the etching selectivity ratio can be improved by including compound (1) as described above. Therefore, the effect of the reduction in etching selectivity ratio due to the inclusion of such other substances can be reduced.

[0046] Furthermore, if the etching solution or other processing solution contains metal, it may have adverse effects on the workpiece (not limited to the silicon surface being etched).

[0047] Therefore, it is preferable that the etching solution does not contain metals (i.e., is below the detection limit). More specifically, it is preferable to avoid the presence of metals at concentrations exceeding the impurity level. Preferably, the content of Ag, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, and Zn is 1 ppm by mass or less, more preferably the content of each of the above metals is 100 ppb by mass or less, even more preferably the content of each of the above metals is 10 ppb by mass or less, and particularly preferably the content of each of the above metals is 1 ppb by mass or less. The metals listed here are metals that are considered to affect the quality of chemicals used in semiconductor manufacturing. The content of these metals can be analyzed by known methods such as inductively coupled plasma mass spectrometry (ICP-MS).

[0048] Furthermore, when etching silicon in the manufacturing of semiconductor chips, it is sometimes preferable not to etch the silicon dioxide portion (surface) of the semiconductor chip. Therefore, the etching solution should contain silicon dioxide (SiO₂) under alkaline conditions. ２ Preferably, the compound does not contain any components that may promote etching. A typical example of such a component is fluoride ions. Therefore, it is preferable that the alkaline organic compound and / or compound (1) described above does not contain fluorine atoms.

[0049] Furthermore, highly hydrophobic substances such as polymers tend to adsorb to silicon, so if the etching solution contains hydrophobic substances, the etching rate may slow down. Therefore, the content of hydrophobic substances in the etching solution is preferably 1 ppm by mass or less, more preferably 1 ppb by mass or less, and even more preferably none (below the detection limit). Highly hydrophobic substances are, for example, substances with 20 or more carbon atoms.

[0050] Furthermore, if an oxidizing agent is present in the silicon etching solution, compound (1) may decompose into ammonia, amine compounds, formic acid, or carbon dioxide through oxidative cleavage. Also, if the oxidizing agent concentration is high, silicon etching may be suppressed, and the etching rate may become significantly slower. For these reasons, it is preferable that the etching solution does not contain an oxidizing agent.

[0051] Furthermore, the etching solution is preferably a homogeneous solution in which all components are dissolved. In addition, to prevent contamination during etching, it is preferable that the number of particles (fine particles) with an equivalent circle diameter of 200 nm or more be 100 or less per mL, more preferably 50 or less per mL, and particularly preferably 10 or less per mL. That is, it is preferable that the number of particles with an equivalent circle diameter of 200 nm or more be 0 or more and 100 or less per mL (i.e., 100 or less per mL), more preferably 0 or more and 50 or less per mL (i.e., 50 or less per mL), and particularly preferably 0 or more and 10 or less per mL (i.e., 10 or less per mL).

[0052] In silicon etching, the pKa of the product, orthosilicic acid, is around 10 (at 23°C), so the etching rate tends to decrease when the pH of the etching solution falls below 10.0. Therefore, the pH of the etching solution according to this embodiment is preferably 9.5 or higher, more preferably 10.0 or higher, and particularly preferably 10.5 or higher. On the other hand, the etching selectivity ratio of silicon to silicon germanium tends to increase as the pH decreases in the range of pH 9.5 or higher. Therefore, the pH of the etching solution according to this embodiment is preferably 13.0 or lower, more preferably 12.5 or lower, even more preferably 12.0 or lower, and particularly preferably 11.5 or lower. In other words, the pH range of the etching solution according to this embodiment is preferably 9.5 or higher and 13.0 or lower, more preferably 9.5 or higher and 12.5 or lower, even more preferably 10.0 or higher and 12.0 or lower, particularly preferably 10.0 or higher and 11.5 or lower, and especially preferably 10.2 or higher and 11.5 or lower. Note that this pH value refers to the value measured at 23°C using the glass electrode method.

[0053] <Method for manufacturing silicon etching solution> The method for manufacturing the silicon etching solution described above is not particularly limited and may include a step of mixing an alkaline organic compound, the compound (1) described above, and water. For example, one method is to mix the alkaline organic compound and compound (1) described above with water to a desired concentration and dissolve them uniformly.

[0054] For the alkaline organic compound and the raw materials for compound (1), it is preferable to use materials that contain as few of the aforementioned metal impurities and insoluble impurities as possible. If necessary, commercially available products can be purified by recrystallization, column purification, ion exchange purification, or filtration before use.

[0055] When using quaternary ammonium hydroxide as the alkaline organic compound, it is preferable to use extremely high-purity quaternary ammonium hydroxide, which is manufactured and sold for semiconductor manufacturing purposes, depending on the type. High-purity quaternary ammonium hydroxide for semiconductor manufacturing is generally sold as an aqueous solution. When manufacturing silicon etching solution, this solution can be used as is and mixed with water, compound (1), etc.

[0056] It is also preferable to use high-purity water with few impurities. The amount of impurities can be evaluated by its electrical resistivity. Specifically, the electrical resistivity of water is preferably 0.1 MΩ·cm or higher, more preferably 15 MΩ·cm or higher, and even more preferably 18 MΩ·cm or higher. Such water with few impurities 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 effect on) the electrical resistivity, making it highly suitable for etching solutions.

[0057] As mentioned above, other substances may be added as needed.

[0058] Furthermore, when using quaternary ammonium hydroxide as the alkaline organic compound, the etching solution may contain halogen salts of quaternary ammonium such as tetramethylammonium chloride, ethyltrimethylammonium iodide, dodecyltrimethylammonium bromide, or decyltrimethylammonium bromide.

[0059] As mentioned above, etching solutions are preferably free of fluoride ions. Therefore, even if the compounds are known to be components of semiconductor manufacturing chemicals, it is preferable not to include fluorides such as ammonium fluoride or tetramethylammonium fluoride. PF ６ Salt, or BF ４ It is preferable not to include salt or other similar ingredients.

[0060] In the manufacture of etching solutions, it is also preferable to remove particles by passing the mixture through a filter with a size of several nanometers to several tens of nanometers after mixing and dissolving each component. If necessary, the filtering process may be performed multiple times.

[0061] Furthermore, in the manufacture of etching solutions, various known treatments can be applied, such as reducing dissolved oxygen by bubbling with an inert gas like high-purity nitrogen gas, in order to obtain the physical properties necessary for the manufacture of semiconductor manufacturing chemicals.

[0062] For mixing and dissolving (and storing) the solutions, it is preferable to use containers or equipment formed or coated with materials known to be used as inner walls for 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 and equipment beforehand.

[0063] <Method for manufacturing semiconductor devices> The method for manufacturing semiconductor devices according to this disclosure includes a step of bringing the silicon etching solution into contact with silicon.

[0064] A method for manufacturing a semiconductor device according to this disclosure is a method for manufacturing a semiconductor device having a silicon substrate, wherein the silicon substrate comprises at least one silicon material selected from the group consisting of a silicon wafer, a silicon single crystal film, a polysilicon film, and an amorphous silicon film, and preferably includes etching using a silicon etching solution according to this disclosure. The silicon single crystal film includes those produced by epitaxial growth.

[0065] The method for manufacturing a semiconductor device according to this disclosure may utilize known methods for manufacturing semiconductor devices, except for etching using the silicon etching solution of this disclosure (for example, having a step of contacting a silicon substrate). For example, it may include one or more steps selected from the group consisting of wafer fabrication, oxide film formation, transistor formation, wiring formation, and CMP steps, which are known steps used in semiconductor manufacturing. It is also preferable to include a step of contacting silicon germanium with the silicon etching solution of this disclosure.

[0066] The method for bringing the silicon etching solution of this disclosure into contact with a silicon substrate is not particularly limited as long as the silicon etching solution and the silicon substrate are in contact, and includes methods such as a substrate holding step of holding the silicon substrate in a horizontal position and a processing solution supply step of supplying the etching solution of this disclosure to the main surface of the substrate while rotating the substrate about a vertical axis of rotation passing through the center of the substrate, or a method including a substrate holding step of holding a plurality of substrates in an upright position and a step of immersing the substrates in an upright position in the etching solution of this disclosure stored in a processing tank.

[0067] If the present disclosure includes a step of contacting silicon-germanium with the silicon etching solution, the step of contacting silicon with silicon and the step of contacting silicon-germanium with the silicon etching solution may be separate steps, but from the viewpoint of manufacturing efficiency, it is preferable to contact the objects containing silicon and silicon-germanium in the same step. Contacting in the same step means contacting the objects containing silicon and silicon-germanium with the silicon etching solution simultaneously. For example, by contacting a device structure having a structure in which an oxide film and / or nitride film is used as an insulating film, and silicon films and silicon-germanium films are alternately stacked, the silicon can be selectively removed from the device structure. Furthermore, it is possible to fabricate nanowire pattern structures for GAA using silicon-germanium, or memory stacking structures such as 3D NAND, while leaving the oxide film and / or nitride film, which are insulating films, intact. As described above, the method for manufacturing a semiconductor device according to the present disclosure preferably includes (1) selectively etching silicon with respect to silicon germanium in a silicon wafer containing a silicon germanium film, and / or (2) selectively etching at least one selected from the group consisting of a silicon single crystal film, a polysilicon film, and an amorphous silicon film with respect to a silicon germanium film in a substrate containing a silicon germanium film.

[0068] <Silicon Substrate, Silicon Wafer, Substrate Processing Method> The silicon substrate processing method according to this disclosure includes a silicon substrate comprising at least one silicon material selected from the group consisting of a silicon wafer, a silicon single crystal film, a polysilicon film, and an amorphous silicon film, and includes etching the silicon material using a silicon etching solution according to this disclosure. Furthermore, the silicon etching solution used at this time is preferably an etching solution after bubbling with an inert gas, as described later. Specifically, for example, this is a silicon wafer processing method in which the silicon etching solution of this disclosure is brought into contact with the surface of the silicon wafer, or a substrate processing method having a silicon film in which the silicon etching solution of this disclosure is brought into contact with the surface of the substrate having a silicon film. Here, the silicon film comprises at least one selected from the group consisting of a silicon single crystal film, a polysilicon film, and an amorphous silicon film.

[0069] A silicon wafer processing method for contacting the silicon etching solution of this disclosure with the surface of a silicon wafer includes a step of supplying the silicon etching solution of this disclosure to etch a silicon single crystal film when etching a silicon wafer, particularly various silicon composite semiconductor devices containing silicon germanium. As described above, the silicon etching solution of this disclosure can selectively etch silicon with respect to silicon germanium. Therefore, the silicon wafer or substrate to be processed may contain silicon germanium. The silicon wafer or substrate processing method of this disclosure may include, using the silicon etching solution of this disclosure, (1) selectively etching silicon with respect to silicon germanium in a silicon wafer containing a silicon germanium film, and / or (2) selectively etching at least one selected from the group consisting of a silicon single crystal film, a polysilicon film, and an amorphous silicon film with respect to silicon germanium in a substrate containing a silicon germanium film.

[0070] A method for processing a substrate having a silicon film, comprising contacting the surface of the substrate having the silicon film with the silicon etching solution of the present disclosure, includes a substrate holding step of holding the substrate having the silicon film in a horizontal position, and a processing solution supply step of supplying the etching solution of the present disclosure to the main surface of the substrate while rotating the substrate about a vertical rotation axis passing through the center of the substrate.

[0071] Other processing methods for substrates having a silicon film include a substrate holding step of holding a plurality of substrates in an upright position, and a step of immersing the substrates in an upright position in the etching solution of the present disclosure stored in a processing tank.

[0072] <Etching Process> The silicon etching solution of this disclosure can be suitably used in the manufacture of semiconductor devices, which includes a step of supplying the etching solution to etch a silicon single crystal film when etching a silicon wafer, particularly various silicon composite semiconductor devices containing silicon germanium.

[0073] The temperature of the silicon etching solution used in etching with the silicon etching solution of this disclosure can be appropriately determined from the range of 20 to 95°C, taking into consideration the desired etching rate, the shape and surface condition of the silicon after etching, productivity, etc., but a range of 23 to 90°C is preferred. Under conditions where the etching solution temperature is 35°C or higher, the etching selectivity ratio between silicon and silicon germanium tends to decrease as the temperature rises. Therefore, if the selectivity ratio is prioritized over the etching rate, a range of 35 to 70°C is preferred, and a range of 35 to 55°C is more preferred.

[0074] When etching using the silicon etching solution of this disclosure, 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. As a method of reducing dissolved oxygen with an inert gas, for example, it is preferable to bubble nitrogen gas at a flow rate of 0.2 L / min per 100 mL of etching solution for 1 hour, while the surface of the etching solution is not exposed to the atmosphere (a gas containing oxygen). In this case, the dissolved oxygen in the etching solution at 43°C can be sufficiently reduced (to less than 0.1 mass ppm). On the other hand, when etching using the silicon etching solution of this disclosure, reducing dissolved oxygen tends to decrease the silicon etching rate. Therefore, in cases where a high silicon etching rate is required, it is better to have dissolved oxygen in the etching solution. Furthermore, reducing dissolved oxygen in the etching solution by bubbling with an inert gas may lead to variations in the etching rate if the oxygen concentration in the chamber where the etching is performed is not strictly controlled, as this can cause the dissolved oxygen concentration in the chemical solution to fluctuate on the surface of the substrate being treated. Therefore, in the processing method and manufacturing method relating to this disclosure, it is preferable to include a step of bubbling the etching solution with an inert gas from the viewpoint of etching selectivity, but it is preferable not to include a step of bubbling the etching solution with an inert gas from the viewpoint of controlling dissolved oxygen concentration and process control.

[0075] When etching using the silicon etching solution of this disclosure, it is sufficient to simply bring the object to be etched into contact with the etching solution by immersion, etc., but an electrochemical etching method in which a constant potential is applied to the object to be etched can also be employed.

[0076] Examples of materials to be etched according to this disclosure include silicon single crystals, polysilicon, and amorphous silicon containing a silicon germanium film, which is a non-target material that needs to be left intact. In addition to the silicon germanium film, non-target materials may also include silicon oxide films, silicon nitride films, and various metal films. Examples include alternating stacks of silicon and silicon germanium, silicon germanium films, silicon oxide films, silicon nitride films, and even silicon, polysilicon, and silicon germanium films deposited on a silicon single crystal, and structures patterned using these films.

[0077] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples.

[0078] The experimental methods / evaluation methods for the examples and comparative examples are as follows.

[0079] (Method for measuring the dissolved oxygen concentration of the etching solution) The dissolved oxygen concentration was measured using a HAMILTON VisiFerm DO ECS 120 H0 dissolved oxygen sensor.

[0080] (Method for measuring the pH of the etching solution) The pH was measured at a temperature of 23°C using a Horiba F-73 benchtop pH meter and a Horiba 9632-10D pH electrode for strong alkaline samples.

[0081] (Method for evaluating silicon etching rate (unit: nm / min)) The weight of a 2 x 1 cm square single-crystal silicon substrate (manufactured by SUMTEC Service), with both front and back surfaces being mirror-finished Si(100) surfaces, was measured before etching. To remove the native oxide film of the Si substrate, it was pre-treated with a 0.5% hydrofluoric acid aqueous solution for 1 minute and then rinsed with water. Subsequently, the Si substrate was immersed in 100 mL of etching solution heated to 43°C for 10 minutes to perform etching. After that, it was washed with ultrapure water and dried. The weight of the substrate after etching was measured in the same manner as before etching. The weight change before and after etching and the density value of typical single-crystal silicon, 2.329 g / cm³, were measured. ３Using the following formula (I), the etching rate per side of the substrate was calculated. Note that in formula (I), the unit of "etching rate" is "nm / min", and the unit of "area of ​​the front and back surfaces of the substrate" is "cm²". ２ The value "2.329," which indicates the density of single-crystal silicon, has units of "g / cm³." ３ The unit for "weight change before and after etching" is "g", and the unit for "etching time" is "min".

[0082] Silicon etching rate (R'100) = Weight change before and after etching × 10 ７ / 2.329 / Area of ​​front and back surfaces of substrate / Etching time (I) (Method for evaluating silicon germanium etching rate (unit: nm / min)) 100 mL of silicon etching solution heated to 43°C was prepared, and a 2 × 1 cm square silicon germanium substrate (a substrate in which silicon germanium (silicon content 75%, germanium content 25%) was epitaxially grown on a silicon substrate (silicon germanium (25%) film, manufactured by Enatec Co., Ltd.)) which had been pretreated with a 0.5% hydrofluoric acid aqueous solution for 2 minutes, washed with water, and dried was immersed in it for 2 minutes. The silicon germanium etching rate (RSiGe) was determined by measuring the film thickness of the substrate before etching (after pretreatment) and after etching using a spectroscopic ellipsometer, determining the amount of etching of the silicon germanium film from the difference in film thickness before and after treatment, and dividing by the etching time to determine the etching rate of the silicon germanium film. (Etching selectivity ratio between silicon and silicon germanium) The etching selectivity ratio (R'100 / RSiGe) between single-crystal silicon (100 planes) and a silicon germanium film was determined from the measurement results of the silicon etching rate and the silicon germanium etching rate.

[0083] The lower limit of measurement for film thickness change using the spectroscopic ellipsometer used is 0.01 nm. Therefore, the lower limit of the etching rate of the silicon germanium film that can be determined by the above method is 0.005 nm / min.

[0084] <Form of each additive used in preparation> ・N-methylglycine (sarcosine), glycine: single powder

[0085] <Reference Example> The etching rates of silicon and silicon germanium were evaluated by using a 2.38 mass% TMAH aqueous solution and performing nitrogen bubbling of the etching solution. The results are shown in Table 1.

[0086] <Examples 1A and 1B> As an organic alkali compound, an aqueous solution of tetramethylammonium hydroxide (TMAH) (25% by mass, manufactured by Tokuyama) was diluted with ultrapure water and mixed until the chemical solution was homogeneous. Then, various additives were added to prepare an aqueous solution with a TMAH concentration of 2.38% by mass and a glycine concentration of 3% by mass, as shown in Table 1. Using this etching solution, the etching rates of silicon and silicon germanium were evaluated under two conditions: when nitrogen bubbling of the etching solution was performed (Example 1B) and when nitrogen bubbling of the etching solution was not performed (Example 1A). Nitrogen bubbling of the etching solution was performed at a supply rate of 0.2 L / min from 40 minutes before the start of the etching process until the end of the etching process. The dissolved oxygen concentration in the etching solution at the start of the etching process was 0.05 ppm by mass when nitrogen bubbling was performed and 5 ppm by mass when nitrogen bubbling was not performed. The results are shown in Table 1. In these embodiments, the etching selectivity ratio (R'100 / RSiGe) between single-crystal silicon (100 planes) and silicon germanium film was excellent under both conditions: 152 when nitrogen bubbling of the etching solution was performed, and 93 when nitrogen bubbling of the etching solution was not performed.

[0087] <Examples 2A and 2B> As shown in Table 1, etching solutions were prepared and evaluated in the same manner as in Examples 1A and 1B, except that the additive was changed from glycine to sarcosine. The results are shown in Table 1.

[0088] <Examples 3-11> Etching solutions were prepared in the same manner as in Example 1A, except that the composition of the etching solution was changed as shown in Table 1, and the etching solution was evaluated without nitrogen bubbling. The results are shown in Table 1. The abbreviations in the table are as follows: ETMAH: Ethyltrimethylammonium hydroxide PTMAH: Propyltrimethylammonium hydroxide BTMAH: Butyltrimethylammonium hydroxide TEAH: Tetraethylammonium hydroxide

[0089] <Comparative Examples 1-6> Etching solutions with the compositions shown in Table 1 were prepared and evaluated without nitrogen bubbling of the etching solution. The results are shown in Table 1.

[0090] In Table 1, "Si ER", "SiGe ER", and "Si ER / SiGe ER Selectivity Ratio" represent the silicon etching rate, the silicon germanium etching rate, and the etching selectivity ratio between single-crystal silicon (100 faces) and a silicon germanium film, respectively.

Claims

1. A silicon etching solution comprising an alkaline organic compound and water, further comprising an amino acid that does not have a cyclic structure, wherein the content of the amino acid is 100 ppm by mass or more.

2. The silicon etching solution according to claim 1, wherein the amino acid that does not have a cyclic structure is an amino acid represented by the following formula (1); In formula (1), R １ R is a hydrocarbon group having 1 to 10 carbon atoms, which may have a hydrogen atom or substituents. ２ This is a hydrocarbon group having 1 to 10 carbon atoms, which may have a hydrogen atom or a substituent.

3. The silicon etching solution according to claim 1 or 2, wherein the pH of the silicon etching solution is 9.5 or higher and 13.0 or lower at 23°C.

4. The silicon etching solution according to any one of claims 1 to 3, wherein the alkaline organic compound is an amine compound or a quaternary ammonium hydroxide.

5. The silicon etching solution according to any one of claims 1 to 4, wherein the amino acid is glycine or sarcosine.

6. The silicon etching solution according to any one of claims 1 to 5, wherein the concentrations of Ag, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, and Zn are all 10 ppb by mass or less.

7. A method for processing a silicon substrate, wherein the silicon substrate comprises at least one silicon material selected from the group consisting of a silicon wafer, a silicon single crystal film, a polysilicon film, and an amorphous silicon film, and comprises etching the silicon material using a silicon etching solution according to any one of claims 1 to 6.

8. A method for processing a silicon substrate according to claim 7, wherein the silicon etching solution is a silicon etching solution after bubbling with an inert gas.

9. A method for processing a silicon wafer or substrate, comprising: selectively etching silicon with respect to silicon germanium in a silicon wafer containing a silicon germanium film using the silicon etching solution described in any one of claims 1 to 6; and / or selectively etching at least one selected from the group consisting of a silicon single crystal film, a polysilicon film, and an amorphous silicon film with respect to silicon germanium in a substrate containing a silicon germanium film.

10. A method for manufacturing a semiconductor device having a silicon substrate, wherein the silicon substrate comprises at least one silicon material selected from the group consisting of a silicon wafer, a silicon single crystal film, a polysilicon film, and an amorphous silicon film, and the method comprises etching the silicon material using a silicon etching solution according to any one of claims 1 to 6.

11. A method for manufacturing a semiconductor device, comprising: selectively etching silicon with respect to silicon germanium in a silicon wafer containing a silicon germanium film using a silicon etching solution according to any one of claims 1 to 6; and / or selectively etching at least one selected from the group consisting of a silicon single crystal film, a polysilicon film, and an amorphous silicon film with respect to a silicon germanium film in a substrate containing a silicon germanium film.

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