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

Abstract

The present invention provides an etching composition that suppresses the dissolution of silicon germanium and promotes the dissolution of silicon, exhibiting excellent selective dissolution of silicon to silicon germanium, as well as an etching method using this etching composition, a method for manufacturing a semiconductor device, and a method for manufacturing a gate-all-around type transistor. [Solution] An etching composition that selectively dissolves silicon in silicon germanium, comprising a quaternary ammonium salt (A) having 8 or more carbon atoms. It may further contain a chelating agent (B). An etching method for etching a structure containing silicon and silicon germanium using this 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 type transistor. [Background technology]

[0002] In accordance with Moore's Law, the miniaturization of integrated circuits is progressing. In recent years, research has focused not only on reducing the size of conventional planar transistors, but also on improving performance by changing the structure, such as with Fin-type transistors (Fin-type FETs) and gate-all-around transistors (GAA-type FETs), as well as on further miniaturization and integration.

[0003] In fin-type FETs, forming fins perpendicular to the silicon substrate not only increases the number of transistors per unit area but also exhibits excellent ON / OFF control performance 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 problems such as the fins collapsing during the washing and drying processes for fin formation.

[0004] In GAA-type FETs, the channel, which is a nanosheet or nanowire, is covered with a gate electrode, increasing the contact area between the channel and the gate electrode, thereby improving the transistor's performance per unit area.

[0005] To form a GAA-type FET, an etching composition is required to selectively etch either 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. [Prior art documents] [Patent Documents]

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

[0007] The etching composition disclosed in Patent Document 1 does not exhibit sufficient selective solubility of silicon in silicon germanium due to the unoptimized type of quaternary ammonium hydroxide compound or the lack of a chelating agent. In the structure disclosed in Patent Document 1, in which silicon and silicon germanium are alternately stacked, low-crystallinity polysilicon is used as the silicon. Therefore, it is unclear whether equivalent selective solubility can be obtained with highly crystalline silicon, which is commonly used in actual semiconductor devices.

[0008] Previously, etching compositions containing various components have been investigated, as described in Patent Document 1, but none of them demonstrated sufficient selective solubility of silicon in silicon germanium. [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The object of the present invention is to provide an etching composition that suppresses the dissolution of silicon germanium, promotes the dissolution of silicon, and exhibits excellent selective dissolution of silicon to silicon germanium. Furthermore, an 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 type transistor. [Means for solving the problem]

[0010] The inventors have found that the etching composition described later suppresses the dissolution of silicon germanium, promotes the dissolution of silicon, and exhibits excellent selective solubility of silicon in silicon germanium.

[0011] In other words, the gist of this invention is as follows:

[0012] [1] An etching composition comprising a quaternary ammonium salt (A) having 8 or more carbon atoms, which selectively dissolves silicon in silicon germanium. [2] The etching composition according to [1], wherein the quaternary ammonium salt (A) having 8 or more carbon atoms is 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 is 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 a quaternary alkylammonium salt in which four alkyl groups are the same in a quaternary ammonium salt (A) having 8 or more carbon atoms is 50% by mass or more out of 100% by 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 a quaternary ammonium salt (A) having 8 or more carbon atoms is 10% by mass or more in 100% by 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% 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 a quaternary ammonium salt (A) having 8 or more carbon atoms to a chelating agent (B) is 5 to 5000. [9] The etching composition according to any one of [1] to [8], further comprising water (C).

[10] Furthermore, an etching composition according to any one of [1] to [9], which contains a water-miscible solvent (D).

[11] The etching composition according to

[10] , wherein the content of the water-miscible solvent (D) is 15% by mass or less in 100% by 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 containing a quaternary ammonium salt (A) having 8 or more carbon atoms, 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, and 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% by mass or more in 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 in 100% by mass of the composition.

[14] An etching method of 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, which includes a 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 type transistor, which includes a step of etching a structure containing silicon and silicon germanium using the etching composition according to any one of [1] to

[13] . [Effect of the Invention]

[0013] The etching composition of the present invention suppresses the dissolution of silicon germanium, promotes the dissolution of silicon, and is excellent in the selective solubility of silicon with respect 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 type transistor of the present invention using such an etching composition of the present invention can suppress the dissolution of silicon germanium and promote the dissolution of silicon in the etching step, and can perform highly precise etching by the excellent selective solubility of silicon with respect to silicon germanium to manufacture a desired product with a good yield.

Embodiments for Carrying Out the Invention

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

[0016] The etching composition of the present invention can selectively dissolve silicon with respect to silicon germanium by containing a quaternary ammonium salt (A) having 8 or more carbon atoms (hereinafter, may be referred to as "component (A)"). The etching composition of the present invention may further contain a chelating agent (B) (hereinafter, may be referred to as "component (B)"), water (C) (hereinafter, may be referred to as "component (C)"), and a water-miscible solvent (D) (hereinafter, may be referred to as "component (D)").

[0017] [[ID=1)]7]<Component (A)> Component (A) is a quaternary ammonium salt having 8 or more carbon atoms. By including a quaternary ammonium salt having 8 or more carbon atoms in the etching composition, the effect of dissolving silicon or silicon germanium is exhibited.

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

[0019] The quaternary alkylammonium salt as component (A) exhibits excellent selective solubility of silicon in silicon germanium, so it is preferable that the four alkyl groups are identical. In particular, it is preferable that component (A) contains 50% by mass or more of a quaternary alkylammonium salt with four identical alkyl groups in 100% by mass, more preferably 70% by mass or more, even more preferably 90% by mass or more, and most preferably 100% by mass of a quaternary alkylammonium salt with four identical alkyl groups.

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

[0021] Among these quaternary ammonium salts with 8 or more carbon atoms, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide, and benzyltrimethylammonium hydroxide are preferred due to their excellent selective solubility of silicon in silicon germanium; tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and benzyltrimethylammonium hydroxide are more preferred; tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide are even more preferred; and tetrabutylammonium hydroxide is the 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, due to its excellent selective solubility of silicon. The content of component (A) is preferably 70% by mass or less, more preferably 55% by mass or less, and even more preferably 40% by mass or less, based on its excellent selective solubility of silicon, in the etching composition.

[0023] From the preferred embodiments of component (A) described above, an etching composition of the present invention is an etching composition comprising component (A), wherein component (A) comprises at least one compound selected from the group consisting of tetrapropylammonium hydroxide and tetrabutylammonium hydroxide, the content of a quaternary alkylammonium salt in component (A) having the same four alkyl groups is 50% by mass or more out of 100% by mass of component (A), and the content of component (A) is 10% by mass or more out of 100% by mass of the composition.

[0024] <Ingredient (B)> Component (B) is a chelating agent. Including a chelating agent in the etching composition provides a protective effect on the silicon germanium.

[0025] Examples of chelating agents include amine compounds, amino acids, and organic acids. These chelating agents may be used individually or in combination of two or more. Among these chelating agents, amine compounds, amino acids, and organic acids are preferred, with amine compounds being more preferred, due to their excellent selective solubility of silicon in silicon germanium.

[0026] Examples of amine compounds 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, and 2-amino-2-methyl-1-propanol. These amine compounds may be used individually 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 due to their excellent selective solubility of silicon in 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, and (2-dihydroxyethyl)glycine. These amino acids may be used individually 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, due to their excellent selective solubility of silicon in silicon germanium.

[0030] Examples of organic acids include oxalic acid, citric acid, tartaric acid, malic acid, and 2-phosphonobutane-1,2,4-tricarboxylic acid. These organic acids may be used individually 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 due to their excellent selective solubility of silicon in 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, due to its excellent selective solubility of silicon in 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, due to its excellent selective solubility of silicon in silicon germanium.

[0033] <Component (C)> The etching composition of the present invention preferably contains water (C) (component (C)) in addition to components (A) and (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, as this facilitates the manufacture 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, as this can improve the etch rate.

[0035] <Ingredient (D)> The etching composition of the present invention preferably contains a water-miscible solvent (D) in addition to components (A) and (B). Including a water-miscible solvent in the etching solution provides a protective effect on the silicon germanium.

[0036] The water-miscible solvent (D) can be any solvent with excellent solubility in water, and a solvent with a solubility parameter (SP value) of 7.0 or higher is preferred. Examples of the water-miscible solvent for 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 individually or in combination of two or more. Among these water-miscible solvents, glycerol, 2-(2-aminoethoxyethanol), ethylene glycol, and propylene glycol are preferred due to their excellent selective solubility of silicon in silicon germanium.

[0037] When the etching composition of the present invention contains component (D), the content of component (D) is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 1% by mass or more, based on 100% by mass of the etching composition, due to its excellent selective solubility of silicon in 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, due to its excellent selective solubility of silicon in silicon germanium.

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

[0039] Other components include, for example, 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 individually 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 5000, more preferably 5 to 3000, and even more preferably 10 to 3000, due to the excellent selective solubility of silicon in 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, due to its excellent selective solubility of silicon in 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, due to its excellent selective solubility of silicon in silicon germanium.

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

[0044] <Physical properties of etching compositions> Etching rate of silicon in the etching composition of the present invention Si Because it exhibits excellent selective solubility of silicon in silicon germanium, a flux of 1 nm / min or more is preferred, and 3 nm / min or more is more preferred.

[0045] Etching rate of silicon germanium in the etching composition of the present invention ER SiGe Because it exhibits excellent selective solubility of silicon in silicon germanium, a flux of 1 nm / min or less is preferred, more preferably 0.8 nm / min or less, and even more preferably 0.5 nm / min or less.

[0046] The solubility selectivity ratio (ER) of silicon germanium and silicon in the etching composition of the present invention Si / ER SiGe ) is preferable to have a value of 4 or higher, and more preferable to 10 or higher, because it exhibits excellent selective solubility of silicon in silicon germanium.

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

[0048] <Etching targets for etching compositions> The etching composition of the present invention suppresses the dissolution of silicon germanium, promotes the dissolution of silicon, and exhibits excellent selective dissolution of silicon relative to silicon germanium. For this reason, the etching composition of the present invention is suitable as an etching target for 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 is necessary for the formation of GAA-type FETs.

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

[0050] Furthermore, the germanium content 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% by mass or less, and more preferably 80% by mass or less, based on 100% by mass of silicon germanium, as this is suitable for etching with the etching composition of the present invention.

[0051] Although silicon-germanium alloy films can be manufactured by known methods of film formation, it is preferable to manufacture them by crystal growth because they exhibit excellent electron and hole mobility after transistor formation.

[0052] Structures containing silicon and silicon germanium, or structures in which silicon and silicon germanium are alternately layered, may have exposed silicon oxide, silicon nitride, silicon carbonitride, etc.

[0053] Furthermore, the etching composition of the present invention, which contains component (A), wherein component (A) contains at least one compound selected from the group consisting of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide, and the content of a quaternary alkylammonium salt in component (A) having the same four alkyl groups is 50% by mass or more out of 100% by mass of component (A), and the content of component (A) is 10% by mass or more out of 100% by mass of the composition, exhibits excellent selective solubility of silicon in silicon germanium and can therefore be suitably used in 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 can be a known method, such as batch etching or sheet etching.

[0056] The etching temperature is preferably 15°C or higher, and more preferably 20°C or higher, as this can improve the etch rate. The etching temperature is preferably 100°C or lower, and more preferably 80°C or lower, from the viewpoint of reducing damage to the substrate and ensuring etching stability. Here, the etching temperature refers 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 that include a step of etching a structure containing silicon and silicon germanium, as they suppress the dissolution of silicon germanium, promote the dissolution of silicon, and exhibit excellent selective dissolution of silicon to silicon germanium. For this reason, the etching composition and etching method of the present invention can be particularly suitably used in the manufacture of GAA-type FETs that include a step of etching a structure containing silicon and silicon germanium. [Examples]

[0058] The present invention will be described in more detail below using examples. The present invention is not limited to the following examples, unless it deviates from its essence.

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

[0060] <Etch rate of silicon> A substrate containing 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) are laminated is immersed in a 0.5 mass% hydrofluoric acid aqueous solution 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 is observed with an electron microscope to measure the width (nm) of the silicon layer, and the etch rate ER of silicon is calculated using the following formula (1). Si [nm / min] was calculated. ER Si [nm / min] = (width of the silicon layer before immersion - width of the silicon layer after immersion) ÷ 15 minutes (1)

[0061] <Etch rate of silicon germanium> A substrate containing a structure in which silicon germanium with a film thickness of 10 nm (width of the silicon germanium layer before immersion = 10 nm) and silicon with a film thickness of 10 nm are laminated is immersed in a 0.5 mass% hydrofluoric acid aqueous solution 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 is 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 is 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 ratio of silicon and silicon germanium> The solubility selectivity ratio of silicon germanium to silicon was calculated using the following formula (3). Dissolution selectivity = ER Si [nm / min]÷ER SiGe [nm / min] (3)

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

[0064] [Examples 2-22, Comparative Examples 1-8] An etching composition was obtained by following the same procedure as in Example 1, except that the types and percentages of raw materials shown in Table 1 were used, and the remainder was made up of 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 suppressed the dissolution of silicon germanium, promoted the dissolution of silicon, and exhibited excellent selective dissolution of silicon relative to silicon germanium.

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

[0068] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications are possible without departing from the intent and scope of the invention. This application is based on Japanese Patent Application No. 2021-002880, filed on 12 January 2021, which is incorporated herein by reference in its entirety. [Industrial applicability]

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

Claims

1. An etching composition that selectively dissolves silicon in silicon germanium, containing a quaternary ammonium salt (A) with 8 or more carbon atoms and not containing a water-miscible solvent (D).

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. The etching composition according to claim 1 or 2, 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. The etching composition according to any one of claims 1 to 3, wherein the content of a quaternary alkylammonium salt in which four alkyl groups are the same in a quaternary ammonium salt (A) having eight or more carbon atoms is 50% by mass or more out of 100% by mass of the quaternary ammonium salt (A) having eight or more carbon atoms.

5. The etching composition according to any one of claims 1 to 4, wherein the content of a quaternary ammonium salt (A) having 8 or more carbon atoms is 10% by mass or more in 100% by mass of the etching composition.

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

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

8. The etching composition according to claim 6 or 7, wherein the mass ratio of a quaternary ammonium salt (A) having 8 or more carbon atoms to a chelating agent (B) is 5 to 5000.

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

10. An etching composition comprising a quaternary ammonium salt (A) having 8 or more carbon atoms, without 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 a quaternary alkylammonium salt in which all four alkyl groups in the quaternary ammonium salt (A) are the same is 50% by mass or more of 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 of 100% by mass of the composition.

11. An etching method for etching a structure containing silicon and silicon germanium using an etching composition according to any one of claims 1 to 10.

12. A method for manufacturing a semiconductor device, comprising the step of etching a structure containing silicon and silicon germanium using an etching composition according to any one of claims 1 to 10.

13. A method for manufacturing a gate-all-around transistor, comprising the step of etching a structure containing silicon and silicon germanium using an etching composition according to any one of claims 1 to 10.

Images