Etching composition, etching method, semiconductor device manufacturing method, and gate-all-around transistor manufacturing method

Abstract

An etching composition that includes a C8 or higher quaternary ammonium salt (A) and selectively dissolves silicon relative to silicon germanium. The etching composition may also include a chelating agent (B). An etching method that involves using the etching composition to etch a structure that includes silicon and silicon germanium. The present invention provides: an etching composition that achieves excellent selective dissolution of silicon relative to silicon germanium, suppressing the dissolution of silicon germanium but promoting the dissolution of silicon; and an etching method, a production method for a semiconductor device, and a production method for a gate-all-around transistor that use the etching composition.

Description

[Technical Field]

[0001] The present invention relates to an etching composition, an etching method, a method for manufacturing a semiconductor device, and a method for manufacturing a gate-all-around transistor. [Background technology]

[0002] In accordance with Moore's Law, integrated circuits are becoming increasingly miniaturized. In recent years, in addition to reducing the size of conventional planar transistors, studies have been conducted to improve performance by changing the structure, such as with fin transistors (fin FETs) and gate-all-around transistors (GAA FETs), as well as to promote further miniaturization and integration.

[0003] In FinFETs, by forming fins perpendicular to the silicon substrate, not only is the number of transistors per unit area increased, but the device also exhibits excellent performance in ON / OFF control at low voltages. To achieve further performance improvements, it is necessary to increase the aspect ratio of the fins, but if the aspect ratio is too large, there are issues such as the fins collapsing during the cleaning and drying processes used to form the fins.

[0004] In a GAA FET, the nanosheet or nanowire that forms the channel is covered with a gate electrode, increasing the contact area between the channel and the gate electrode, thereby improving the transistor performance per unit area.

[0005] To form a GAA FET, an etching composition is required to selectively etch silicon or silicon germanium from a structure in which silicon and silicon germanium are alternately stacked. As such an etching composition, Patent Document 1 discloses a composition containing a quaternary ammonium hydroxide compound, specifically ethyltrimethylammonium hydroxide.

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-050364

[0007] The etching composition disclosed in Patent Document 1 does not have sufficient selective solubility of silicon relative to silicon germanium because the type of quaternary ammonium hydroxide compound is not optimized or a chelating agent is not blended. The structure disclosed in Patent Document 1, in which silicon and silicon germanium are alternately stacked, uses polysilicon with low crystallinity as the silicon, and it is therefore unclear whether the same selective dissolution can be achieved with highly crystalline silicon, which is often used in actual semiconductor devices.

[0008] Previously, etching compositions containing various components have been investigated, as in Patent Document 1, but none of them could be said to have sufficient selective solubility of silicon in silicon germanium. Summary of the Invention

[0009] An object of the present invention is to provide an etching composition that suppresses the dissolution of silicon germanium, promotes the dissolution of silicon, and has excellent selective solubility of silicon relative to silicon germanium. Another object of the present invention is to provide an etching method using this etching composition, a method for manufacturing a semiconductor device, and a method for manufacturing a gate-all-around transistor. [Means for solving the problem]

[0010] The present inventors have found that the etching composition described below inhibits the dissolution of silicon germanium, promotes the dissolution of silicon, and has excellent selective solubility of silicon relative to silicon germanium.

[0011] That is, the gist of the present invention is as follows.

[0012] [1] An etching composition that selectively dissolves silicon relative to silicon germanium, comprising a quaternary ammonium salt (A) having 8 or more carbon atoms. [2] The etching composition according to [1], wherein the quaternary ammonium salt (A) having 8 or more carbon atoms contains at least one compound selected from the group consisting of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide, and benzyltrimethylammonium hydroxide. [3] The etching composition according to [1] or [2], wherein the quaternary ammonium salt (A) having 8 or more carbon atoms contains at least one compound selected from the group consisting of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide. [4] The etching composition according to any one of [1] to [3], wherein the content of quaternary alkylammonium salts in which the four alkyl groups in the quaternary ammonium salt (A) having 8 or more carbon atoms are the same is 50 mass% or more in 100 mass% of the quaternary ammonium salt (A) having 8 or more carbon atoms. [5] The etching composition according to any one of [1] to [4], wherein the content of the quaternary ammonium salt (A) having 8 or more carbon atoms is 10 mass % or more in 100 mass % of the etching composition. [6] The etching composition according to any one of [1] to [5], further comprising a chelating agent (B). [7] The etching composition according to [6], wherein the content of the chelating agent (B) is 0.001% by mass to 25% by mass in 100% by mass of the etching composition. [8] The etching composition according to [6] or [7], wherein the mass ratio of the quaternary ammonium salt (A) having 8 or more carbon atoms to the chelating agent (B) is 5 to 5,000. [9] The etching composition according to any one of [1] to [8], further comprising water (C).

[10] The etching composition according to any one of [1] to [9], further comprising a water-miscible solvent (D).

[11] The etching composition according to

[10] , wherein the content of the water-miscible solvent (D) is 15 mass % or less in 100 mass % of the etching composition.

[12] The etching composition according to

[10] or

[11] , wherein the mass ratio of the quaternary ammonium salt (A) having 8 or more carbon atoms to the water-miscible solvent (D) is 1 or more.

[13] An etching composition comprising a quaternary ammonium salt (A) having 8 or more carbon atoms, wherein the quaternary ammonium salt (A) having 8 or more carbon atoms comprises at least one compound selected from the group consisting of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide, wherein the content of quaternary alkylammonium salts in which all four alkyl groups in the quaternary ammonium salt (A) having 8 or more carbon atoms is the same is 50% by mass or more relative to 100% by mass of the quaternary ammonium salt (A) having 8 or more carbon atoms, and the content of the quaternary ammonium salt (A) having 8 or more carbon atoms is 10% by mass or more relative to 100% by mass of the composition.

[14] An etching method, comprising etching a structure containing silicon and silicon germanium using the etching composition according to any one of [1] to

[13] .

[15] A method for manufacturing a semiconductor device, comprising the step of etching a structure containing silicon and silicon germanium using the etching composition according to any one of [1] to

[13] .

[16] A method for manufacturing a gate-all-around transistor, comprising the step of etching a structure containing silicon and silicon germanium using the etching composition according to any one of [1] to

[13] . [Effects of the Invention]

[0013] The etching composition of the present invention inhibits the dissolution of silicon germanium, promotes the dissolution of silicon, and exhibits excellent selective solubility of silicon relative to silicon germanium.

[0014] The etching method of the present invention, the method for manufacturing a semiconductor device of the present invention, and the method for manufacturing a gate-all-around transistor of the present invention, which use the etching composition of the present invention, suppress dissolution of silicon germanium and promote dissolution of silicon in the etching step, and due to the excellent selective solubility of silicon relative to silicon germanium, can perform highly accurate etching and manufacture desired products with a high yield. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention will be described in detail below. The present invention is not limited to the following embodiments, and can be practiced with various modifications within the scope of the gist. When the expression "to" is used in this specification, it is used as an expression including the numerical values ​​or physical property values ​​before and after it.

[0016] The etching composition of the present invention contains a quaternary ammonium salt (A) having 8 or more carbon atoms (hereinafter sometimes referred to as "component (A)"), and is therefore capable of selectively dissolving silicon relative to silicon germanium. The etching composition of the present invention may further contain a chelating agent (B) (hereinafter, sometimes referred to as "component (B)"), water (C) (hereinafter, sometimes referred to as "component (C)"), and a water-miscible solvent (D) (hereinafter, sometimes referred to as "component (D)").

[0017] <Component (A)> Component (A) is a quaternary ammonium salt having a carbon number of 8 or more. When the etching composition contains a quaternary ammonium salt having a carbon number of 8 or more, it exhibits the effect of dissolving silicon and silicon germanium.

[0018] The number of carbon atoms in component (A) is preferably 8 to 32, and more preferably 12 to 24, because this provides excellent selective solubility of silicon relative to silicon germanium. Examples of quaternary ammonium salts of component (A) having 8 or more carbon atoms include quaternary alkylammonium salts such as tetraalkylammonium hydroxides which may have a substituent on the alkyl group, such as tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide, and benzyltrimethylammonium hydroxide.

[0019] The quaternary alkylammonium salt as component (A) preferably has the same four alkyl groups, since it has excellent selective solubility of silicon relative to silicon germanium. In particular, component (A) preferably contains 50% by mass or more of quaternary alkylammonium salts having the same four alkyl groups, more preferably 70% by mass or more, even more preferably 90% by mass or more, per 100% by mass of component (A), and most preferably contains 100% by mass of quaternary alkylammonium salts having the same four alkyl groups.

[0020] These quaternary ammonium salts having 8 or more carbon atoms may be used alone or in combination of two or more.

[0021] Among these quaternary ammonium salts having 8 or more carbon atoms, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide, and benzyltrimethylammonium hydroxide are preferred because they have excellent selective solubility of silicon relative to silicon germanium, with tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and benzyltrimethylammonium hydroxide being more preferred, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide being even more preferred, and tetrabutylammonium hydroxide being most preferred.

[0022] The content of component (A) is preferably 1% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, based on 100% by mass of the etching composition, because it has excellent selective solubility of silicon. The content of component (A) is preferably 70 mass % or less, more preferably 55 mass % or less, and even more preferably 40 mass % or less, based on 100 mass % of the etching composition, because it has excellent selective solubility of silicon.

[0023] From the preferred embodiment of the component (A) described above, examples of the etching composition of the present invention include an etching composition containing component (A), in which component (A) contains at least one compound selected from the group consisting of tetrapropylammonium hydroxide and tetrabutylammonium hydroxide, in which the content of quaternary alkylammonium salt in which the four alkyl groups are the same in component (A) is 50 mass% or more in 100 mass% of component (A), and the content of component (A) is 10 mass% or more in 100 mass% of the composition.

[0024] <Ingredient (B)> Component (B) is a chelating agent. By including a chelating agent in the etching composition, the effect of protecting silicon germanium is exhibited.

[0025] Examples of the chelating agent include amine compounds, amino acids, organic acids, etc. These chelating agents may be used alone or in combination of two or more. Among these chelating agents, amine compounds, amino acids, and organic acids are preferred, and amine compounds are more preferred, because they have excellent selective solubility of silicon relative to silicon germanium.

[0026] Examples of the amine compound include ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid, diethylenetriaminepentakis(methylphosphonic acid), ethylenediamine-N,N'-bis[2-(2-hydroxyphenyl)acetic acid], N,N'-bis(3-aminopropane)ethylenediamine, N-methyl-1,3-diaminopropane, 2-aminoethanol, N-methyldiethanolamine, 2-amino-2-methyl-1-propanol, etc. These amine compounds may be used alone or in combination of two or more.

[0027] Among these amine compounds, ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid, diethylenetriaminepentakis(methylphosphonic acid), ethylenediamine-N,N'-bis[2-(2-hydroxyphenyl)acetic acid], N,N'-bis(3-aminopropane)ethylenediamine, N-methyl-1,3-diaminopropane, 2-aminoethanol, N-methyldiethanolamine, and 2-amino-2-methyl-1-propanol are preferred because they have excellent selective solubility of silicon relative to silicon germanium, and ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid, diethylenetriaminepentakis(methylphosphonic acid), and ethylenediamine-N,N'-bis[2-(2-hydroxyphenyl)acetic acid] are more preferred.

[0028] Examples of amino acids include glycine, arginine, histidine, (2-dihydroxyethyl)glycine, etc. These amino acids may be used alone or in combination of two or more.

[0029] Among these amino acids, glycine, arginine, histidine, and (2-dihydroxyethyl)glycine are preferred, and (2-dihydroxyethyl)glycine is more preferred, because they have excellent selective solubility of silicon relative to silicon germanium.

[0030] Examples of organic acids include oxalic acid, citric acid, tartaric acid, malic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, etc. These organic acids may be used alone or in combination of two or more.

[0031] Among these organic acids, oxalic acid, citric acid, tartaric acid, malic acid, and 2-phosphonobutane-1,2,4-tricarboxylic acid are preferred because they have excellent selective solubility of silicon relative to silicon germanium, and citric acid and 2-phosphonobutane-1,2,4-tricarboxylic acid are more preferred.

[0032] The content of component (B) is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and even more preferably 0.01% by mass or more, based on 100% by mass of the etching composition, because it has excellent selective solubility of silicon relative to silicon germanium. The content of component (B) is preferably 25% by mass or less, more preferably 10% by mass or less, and even more preferably 6% by mass or less, based on 100% by mass of the etching composition, because it has excellent selective solubility of silicon relative to silicon germanium.

[0033] <Component (C)> The etching composition of the present invention preferably contains water (C) (component (C)) in addition to component (A) and component (B).

[0034] The content of component (C) is preferably 25% by mass or more, more preferably 40% by mass or more, and even more preferably 55% by mass or more, based on 100% by mass of the etching composition, because this facilitates production of the etching composition. The content of component (C) is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 75% by mass or less, based on 100% by mass of the etching composition, because this can improve the etch rate.

[0035] <Ingredient (D)> The etching composition of the present invention preferably contains a water-miscible solvent (D) (component (D)) in addition to components (A) and (B). By including a water-miscible solvent in the etching solution, the effect of protecting silicon germanium is exhibited.

[0036] The water-miscible solvent (D) may be any solvent that has excellent solubility in water, and is preferably a solvent with a solubility parameter (SP value) of 7.0 or more. Examples of the water-miscible solvent of component (D) include polar protic solvents such as isopropanol, ethylene glycol, propylene glycol, methanol, ethanol, propanol, butanol, glycerol, and 2-(2-aminoethoxyethanol); polar aprotic solvents such as acetone, dimethyl sulfoxide, N,N-dimethylformamide, N-methylpyrrolidone, and acetonitrile; and nonpolar solvents such as hexane, benzene, toluene, and diethyl ether. These water-miscible solvents may be used alone or in combination of two or more. Among these water-miscible solvents, glycerol, 2-(2-aminoethoxyethanol), ethylene glycol, and propylene glycol are preferred because of their excellent selective solubility of silicon relative to silicon germanium.

[0037] When the etching composition of the present invention contains component (D), the content of component (D) is preferably 0.01 mass% or more, more preferably 0.1 mass% or more, and even more preferably 1 mass% or more, relative to 100 mass% of the etching composition, because the etching composition has excellent selective solubility of silicon relative to silicon germanium. The content of component (D) is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, based on 100% by mass of the etching composition, because it has excellent selective solubility of silicon relative to silicon germanium.

[0038] <Other ingredients> The etching composition of the present invention may contain other components in addition to the component (A), the component (B), the component (C), and the component (D).

[0039] Examples of other components include surfactants such as anionic surfactants, nonionic surfactants, and cationic surfactants; water-soluble polymers such as polyvinyl alcohol, polyethylene glycol, polypropylene glycol, polyethyleneimine, polypropyleneimine, and polyacrylic acid; oxidizing agents such as hydrogen peroxide, perchloric acid, and periodic acid; and reducing agents such as ascorbic acid, gallic acid, pyrogallol, pyrocatechol, resorcinol, hydroquinone, and 8-hydroxyquinoline. These other components may be used alone or in combination of two or more.

[0040] <Mass ratio of each component> When the etching composition of the present invention contains component (A) and component (B), the mass ratio of component (A) to component (B) in the etching composition of the present invention (mass of component (A) / mass of component (B), hereinafter referred to as "(A) / (B)") is preferably 5 to 5,000, more preferably 5 to 3,000, and even more preferably 10 to 3,000, in view of excellent selective solubility of silicon relative to silicon germanium.

[0041] When the etching solution of the present invention contains component (D), the mass ratio of component (A) to component (D) (mass of component (A) / mass of component (D), hereinafter referred to as "(A) / (D)") is preferably 0.01 to 1000, and more preferably 0.1 to 100, in order to provide excellent selective solubility of silicon relative to silicon germanium.

[0042] When the etching solution of the present invention contains component (D), the mass ratio of component (B) to component (D) (mass of component (B) / mass of component (D), hereinafter referred to as "(B) / (D)") is preferably 2 to 2000, and more preferably 5 to 1000, in order to provide excellent selective solubility of silicon relative to silicon germanium.

[0043] <Method of manufacturing etching composition> The method for producing the etching composition of the present invention is not particularly limited, and the etching composition can be produced by mixing component (A) with, as necessary, component (B), component (C), component (D), and other components. The order of mixing is not particularly limited, and all of the components may be mixed at once, or some of the components may be mixed in advance and then the remaining components may be mixed.

[0044] <Physical properties of etching composition> The silicon etch rate ER of the etching composition of the present invention Si Since the selective solubility of silicon in silicon germanium is excellent, the rate is preferably 1 nm / min or more, and more preferably 3 nm / min or more.

[0045] The silicon germanium etch rate ER of the etching composition of the present invention SiGe Since the selective solubility of silicon in silicon germanium is excellent, the rate is preferably 1 nm / min or less, more preferably 0.8 nm / min or less, and even more preferably 0.5 nm / min or less.

[0046] The dissolution selectivity (ER) of the etching composition of the present invention between silicon germanium and silicon Si / ER SiGe ) is preferably 4 or more, more preferably 10 or more, because this provides excellent selective solubility of silicon in silicon germanium.

[0047] Etch Rate ER Si , etch rate ER SiGe The dissolution selectivity ratio is measured and calculated by the method described in the Examples section below.

[0048] <Target to be etched by etching composition> The etching composition of the present invention inhibits dissolution of silicon germanium, promotes dissolution of silicon, and exhibits excellent selective solubility of silicon relative to silicon germanium. Therefore, the etching composition of the present invention is suitable for etching structures containing silicon and silicon germanium, such as semiconductor devices, and is particularly suitable for structures in which silicon and silicon germanium are alternately stacked, which are necessary for forming a GAA type FET.

[0049] The silicon content in the silicon germanium to be etched is preferably 10 mass % or more, more preferably 20 mass % or more, based on 100 mass % of silicon germanium, in order to be suitable for etching with the etching composition of the present invention. On the other hand, the silicon content in silicon germanium is preferably 95 mass % or less, more preferably 85 mass % or less, based on 100 mass % of silicon germanium, in order to be suitable for etching with the etching composition of the present invention.

[0050] Furthermore, the content of germanium in silicon germanium is preferably 5% by mass or more, and more preferably 15% by mass or more, based on 100% by mass of silicon germanium, as this is suitable for etching with the etching composition of the present invention. On the other hand, the germanium content in silicon germanium is preferably 90 mass % or less, more preferably 80 mass % or less, based on 100 mass % of silicon germanium, in order to be suitable for etching with the etching composition of the present invention.

[0051] The silicon germanium alloy film may be produced by deposition using a known method, but is preferably produced by deposition using a crystal growth method, since this provides excellent mobility of electrons and holes after the transistor is formed.

[0052] In a structure containing silicon and silicon germanium or a structure in which silicon and silicon germanium are alternately stacked, silicon oxide, silicon nitride, silicon carbonitride, etc. may be exposed.

[0053] Furthermore, the etching composition of the present invention contains component (A), which contains at least one compound selected from the group consisting of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide, and in which the content of quaternary alkylammonium salt in which all four alkyl groups are the same is 50 mass% or more relative to 100 mass% of component (A), and the content of component (A) is 10 mass% or more relative to 100 mass% of the composition, has excellent selective solubility of silicon relative to silicon germanium, and can therefore be suitably used for structures containing silicon and silicon germanium.

[0054] <Etching method> The etching method of the present invention is a method for etching a structure containing silicon and silicon germanium using the etching composition of the present invention.

[0055] The etching method may be a known method, such as a batch method or a single wafer method.

[0056] The temperature during etching is preferably 15° C. or higher, more preferably 20° C. or higher, since this can improve the etching rate. The temperature during etching is preferably 100° C. or less, more preferably 80° C. or less, from the viewpoint of reducing damage to the substrate and ensuring etching stability. Here, the temperature during etching corresponds to the temperature of the etching composition during etching.

[0057] <Application> The etching composition and etching method of the present invention can be suitably used in the manufacture of semiconductor devices, which includes a step of etching a structure containing silicon and silicon germanium, and suppresses dissolution of silicon germanium, promotes dissolution of silicon, and exhibits excellent selective solubility of silicon relative to silicon germanium. Therefore, the etching composition and etching method of the present invention can be suitably used in the manufacture of GAA-type FETs, which includes a step of etching a structure containing silicon and silicon germanium. [Example]

[0058] The present invention will be described in more detail below using examples. The present invention is not limited to the following examples, as long as it does not deviate from the gist of the invention.

[0059] <Raw materials> In the following examples and comparative examples, the following materials were used as raw materials for producing the etching compositions. Component (A-1): Tetrabutylammonium hydroxide Ingredient (A-2): Tetrapropylammonium hydroxide Component (A'-1): Ammonia Component (A'-2): Tetramethylammonium hydroxide Component (A'-3): Ethyltrimethylammonium hydroxide Ingredient (B-1): Ethylenediamine Component (B-2): 1,3-diaminopropane Ingredient (B-3): Ethylenediaminetetraacetic acid Ingredient (B-4): Diethylenetriaminepentaacetic acid Ingredient (B-5): Diethylenetriaminepentakis(methylphosphonic acid) Component (B-6): Ethylenediamine-N,N'-bis[2-(2-hydroxyphenyl)acetic acid] Component (B-7): N,N'-bis(3-aminopropane)ethylenediamine Ingredient (B-8): N-methyl-1,3-diaminopropane Component (B-9): 2-phosphonobutane-1,2,4-tricarboxylic acid Ingredient (B-10): 2-aminoethanol Ingredient (B-11): N-methyldiethanolamine Ingredient (B-12): 2-amino-2-methyl-1-propanol Ingredient (C-1): Water Ingredient (D-1): Glycerol Component (D-2): 2-(2-aminoethoxyethanol) Other ingredients: 8-hydroxyquinoline (referred to as "(E-1)" in Table 1)

[0060] <Silicon etch rate> A substrate including a structure in which silicon germanium with a film thickness of 10 nm and silicon with a film thickness of 10 nm (width of the silicon layer before immersion = 10 nm) were stacked was immersed in a 0.5 mass % aqueous solution of hydrofluoric acid for 30 seconds, rinsed with ultrapure water, and then immersed in the etching compositions obtained in the Examples and Comparative Examples at 40°C for 15 minutes. The cross section of the substrate after immersion was observed with an electron microscope to measure the width (nm) of the silicon layer, and the silicon etch rate ER was calculated using the following formula (1): Si [nm / min] was calculated. ER Si [nm / min] = (Width of silicon layer before immersion - Width of silicon layer after immersion) ÷ 15 min (1)

[0061] <Silicon germanium etch rate> A substrate including a structure in which silicon germanium with a thickness of 10 nm (width of the silicon germanium layer before immersion = 10 nm) and silicon with a thickness of 10 nm were stacked was immersed in a 0.5 mass % aqueous solution of hydrofluoric acid for 30 seconds, rinsed with ultrapure water, and then immersed in the etching compositions obtained in the Examples and Comparative Examples at 40°C for 15 minutes. The cross section of the substrate after immersion was observed with an electron microscope to measure the width (nm) of the silicon germanium layer, and the etch rate ER of the silicon germanium layer was calculated using the following formula (2): SiGe [nm / min] was calculated. ER SiGe[nm / min] = (Width of silicon germanium layer before immersion - Width of silicon germanium layer after immersion) ÷ 15 min (2)

[0062] <Dissolution selectivity between silicon and silicon germanium> The dissolution selectivity of silicon germanium to silicon was calculated using the following formula (3). Dissolution selectivity ratio = ER Si [nm / min]÷ER SiGe [nm / min] (3)

[0063] [Example 1] An etching composition was obtained by mixing the components so that, based on 100 mass% of the etching composition, component (A-1) was 26 mass%, component (B-1) was 0.01 mass%, and component (C-1) was the remainder. The evaluation results of the obtained etching compositions are shown in Table 1.

[0064] [Examples 2 to 22, Comparative Examples 1 to 8] An etching composition was obtained in the same manner as in Example 1, except that the types and contents of the raw materials shown in Table 1 were used, with the remainder being component (C-1). The evaluation results of the obtained etching compositions are shown in Table 1.

[0065] [Table 1]

[0066] As can be seen from Table 1, the etching compositions obtained in Examples 1 to 22 inhibited the dissolution of silicon germanium, promoted the dissolution of silicon, and were excellent in the selective solubility of silicon relative to silicon germanium.

[0067] On the other hand, among Comparative Examples 1 to 8 in which the type of component (A) was different from that of the present invention, the etching compositions obtained in Comparative Examples 3 to 7 promoted the dissolution of silicon germanium and were poor in the selective solubility of silicon relative to silicon germanium. Comparative Examples 1, 2 and 8 were relatively excellent in the selective solubility of silicon in silicon germanium, but were poor in the solubility of silicon.

[0068] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2021-002880, filed on January 12, 2021, the entire contents of which are incorporated by reference. [Industrial Applicability]

[0069] The etching composition of the present invention and the etching method of the present invention using this etching composition inhibit dissolution of silicon germanium, promote dissolution of silicon, and exhibit excellent selective solubility of silicon relative to silicon germanium. Therefore, the etching composition of the present invention and the etching method of the present invention using this etching composition can be suitably used in the manufacture of semiconductor devices, and in particular, in the manufacture of GAA type FETs.

Claims

1. An etching composition that selectively dissolves silicon relative to silicon germanium, comprising a quaternary ammonium salt (A) having 8 or more carbon atoms and a water-miscible solvent (D), wherein the mass ratio of the quaternary ammonium salt (A) having 8 or more carbon atoms to the water-miscible solvent (D) is 1 or more.

2. 2. The etching composition according to claim 1, wherein the quaternary ammonium salt (A) having 8 or more carbon atoms comprises at least one compound selected from the group consisting of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide, and benzyltrimethylammonium hydroxide.

3. 3. The etching composition according to claim 1, wherein the quaternary ammonium salt (A) having 8 or more carbon atoms comprises at least one compound selected from the group consisting of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.

4. 4. The etching composition according to claim 1, wherein the content of the quaternary alkylammonium salt in which the four alkyl groups in the quaternary ammonium salt (A) having 8 or more carbon atoms are the same is 50 mass% or more in 100 mass% of the quaternary ammonium salt (A) having 8 or more carbon atoms.

5. 5. The etching composition according to claim 1, wherein the content of the quaternary ammonium salt (A) having 8 or more carbon atoms is 10 mass% or more in 100 mass% of the etching composition.

6. The etching composition according to any one of claims 1 to 5, further comprising a chelating agent (B). thing.

7. 7. The etching composition according to claim 6, wherein the content of the chelating agent (B) is 0.001 mass % to 25 mass % in 100 mass % of the etching composition.

8. 8. The etching composition according to claim 6, wherein the mass ratio of the quaternary ammonium salt (A) having 8 or more carbon atoms to the chelating agent (B) is 5 to 5,000.

9. The etching composition according to any one of claims 1 to 8, further comprising water (C).

10. The etching composition according to any one of claims 1 to 9, wherein the content of the water-miscible solvent (D) is 15 mass% or less in 100 mass% of the etching composition.

11. 1. An etching composition comprising: a quaternary ammonium salt (A) having 8 or more carbon atoms; and a water-miscible solvent (D), wherein the quaternary ammonium salt (A) having 8 or more carbon atoms comprises at least one compound selected from the group consisting of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide; the content of quaternary alkylammonium salts in which all four alkyl groups in the quaternary ammonium salt (A) having 8 or more carbon atoms is 50% by mass or more relative to 100% by mass of the quaternary ammonium salt (A) having 8 or more carbon atoms; the content of the quaternary ammonium salt (A) having 8 or more carbon atoms is 10% by mass or more relative to 100% by mass of the composition; and the mass ratio of the quaternary ammonium salt (A) having 8 or more carbon atoms to the water-miscible solvent (D) is 1 or more.

12. An etching method for etching a structure containing silicon and silicon germanium using the etching composition according to any one of claims 1 to 11.

13. A method for manufacturing a semiconductor device, comprising the step of etching a structure containing silicon and silicon germanium using the etching composition according to any one of claims 1 to 11.

14. A method for manufacturing a gate-all-around transistor, comprising the step of etching a structure containing silicon and silicon germanium using the etching composition according to any one of claims 1 to 11.

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