Etching liquid, etching method, and method for manufacturing semiconductor device

Abstract

The present invention pertains to an etching liquid excellent in selective solubility of the 110 plane of a silicon crystal with respect to the 100 plane of the silicon crystal.　An etching liquid comprising an alkaline compound (A) and at least one compound (B) selected from the group consisting of an oxidizing agent (B1) and a cationic surfactant (B2), wherein ER110 / ER100>1.　In formula, ER110 is an etching rate with respect to the 110 plane of the silicon crystal, and ER100 is an etching rate with respect to the 100 plane of the silicon crystal.

Description

Etching solution, etching method, and semiconductor device manufacturing method

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

[0002] In accordance with Moore's Law, the miniaturization of integrated circuits is progressing. In recent years, in addition to reducing the size of conventional planar transistors, studies have been conducted to further miniaturize and integrate transistors by changing the structure from planar to three-dimensional, such as fin transistors (fin field effect transistors) and gate-all-around transistors (GAA field effect transistors). As a transistor structure that is expected to enable further miniaturization, vertical field effect transistors (VFETs) are being studied, which change the structure from conventional planar transistors to vertical, allowing for further miniaturization and improved performance.

[0003] In a GAA FET, a nanosheet or nanowire 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.

[0004] VFETs have a structure in which nanosheet or nanowire-like channels are stacked vertically, and the area of ​​the standard cell layout is smaller than that of planar transistors (HFETs), thereby improving the transistor performance per unit area.

[0005] To form a GAA FET or a VFET, an etching solution that dissolves silicon is required in the etching process. For example, Patent Documents 1 and 2 disclose etching solutions that contain alkaline compounds as etching solutions that dissolve silicon.

[0006] JP 2017-108122 A JP 2021-136429 A

[0007] However, the etching solutions disclosed in Patent Documents 1 and 2 are inferior in selective dissolution of the 110 plane of silicon crystal relative to the 100 plane of silicon crystal.

[0008] In particular, in recent years, there has been a strong demand for miniaturization of FETs, and it is necessary to control etching of silicon according to its plane orientation in narrow gaps of a few tens of nanometers. FETs, which are structured perpendicular to the 100 plane of silicon crystals, require etching from the horizontal direction to form nano-shapes, so an etching solution with excellent selective solubility for the 110 plane of silicon crystals is required. In particular, selective solubility according to plane orientation is not easy to control because the surface is composed of the same elements.

[0009] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an etching solution that has excellent selective dissolution of the 110 plane of a silicon crystal relative to the 100 plane of a silicon crystal. Another object of the present invention is to provide an etching method using the etching solution, a method for manufacturing a semiconductor device, a method for manufacturing a vertical transistor, and a method for manufacturing a gate-all-around transistor.

[0010] In a first aspect, the present inventors have conducted extensive research and found that an etching solution containing an alkaline compound (A) and at least one compound (B) selected from the group consisting of an oxidizing agent (B1) and a cationic surfactant (B2) has excellent selective solubility of the 110 plane of a silicon crystal relative to the 100 plane of a silicon crystal, thereby completing the present invention.

[0011] In addition, as a second aspect, the present inventors have found that an etching solution containing an alkylammonium hydroxide (A1) having an alkyl group having 10 or more carbon atoms has excellent selective solubility of the 110 plane of a silicon crystal relative to the 100 plane of a silicon crystal, and have thus completed the present invention.

[0012] That is, the gist of the present invention is as follows: [1] An ER containing an alkaline compound (A) and at least one compound (B) selected from the group consisting of an oxidizing agent (B1) and a cationic surfactant (B2), １１０ / ER １００ >1. (The ER １１０ is the etching rate for the 110 plane of the silicon crystal, and the ER １００is the etching rate for the (100) plane of the silicon crystal.) [2] The etching solution according to [1], wherein the alkaline compound (A) contains at least one compound selected from the group consisting of a quaternary ammonium hydroxide compound, potassium hydroxide, and calcium hydroxide. [3] The etching solution according to either [1] or [2], wherein the oxidizing agent (B1) contains hydrogen peroxide. [4] The etching solution according to any one of [1] to [3], wherein the cationic surfactant (B2) contains a quaternary ammonium compound. [5] The etching solution according to any one of [1] to [4], wherein the cationic surfactant (B2) contains at least one compound selected from the group consisting of an alkyl group-containing quaternary ammonium compound, a pyridinium ring-containing quaternary ammonium compound, a pyrrolidinium ring-containing quaternary ammonium compound, and a piperidinium ring-containing quaternary ammonium compound. [6] The etching solution according to any one of [1] to [5], further containing water. [7] The etching solution according to [6], wherein the content of water in 100% by mass of the etching solution is 60% by mass or more. [8] The etching solution according to any one of [1] to [7], wherein the content of the alkaline compound (A) in 100% by mass of the etching solution is 0.1% by mass to 39.99% by mass. [9] The etching solution according to any one of [1] to [8], wherein the content of the compound (B) in 100% by mass of the etching solution is 0.01% by mass to 5% by mass.

[10] The etching solution according to any one of [1] to [9], wherein the ratio of the mass of the compound (B) to the mass of the alkaline compound (A) is 0.001 to 2.

[11] ER １１１ / ER １１０ The etching solution according to any one of [1] to

[10] , wherein the ER １１１is the etching rate for the 111 plane of a silicon crystal.)

[12] The etching solution according to any one of [1] to

[11] , which is used as an etching solution for dissolving silicon.

[13] The etching solution according to any one of [1] to

[12] , which dissolves the 110 plane of a silicon crystal relative to the 100 plane of a silicon crystal.

[14] The etching solution according to any one of [1] to

[13] , wherein the silicon is single crystal silicon.

[15] An etching method for etching a silicon-containing structure using the etching solution according to any one of [1] to

[14] .

[16] A method for manufacturing a semiconductor device, comprising the step of etching a silicon-containing structure using the etching solution according to any one of [1] to

[14] .

[17] A method for manufacturing a vertical transistor, comprising the step of etching a silicon-containing structure using the etching solution according to any one of [1] to

[14] .

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

[14] .

[19] A method for etching a silicon-containing structure, comprising the step of selectively etching a (110) plane of a silicon crystal relative to a (100) plane of the silicon crystal using an etching solution containing an alkaline compound (A) and at least one compound (B) selected from the group consisting of an oxidizing agent (B1) and a cationic surfactant (B2).

[20] A method for manufacturing a semiconductor device, comprising the step of selectively etching a (110) plane of a silicon crystal relative to a (100) plane of the silicon crystal using an etching solution containing an alkaline compound (A) and at least one compound (B) selected from the group consisting of an oxidizing agent (B1) and a cationic surfactant (B2).

[0013] The etching solution of the present invention has excellent selective solubility in the 110 plane of a silicon crystal relative to the 100 plane of a silicon crystal. The etching method of the present invention, the semiconductor device manufacturing method of the present invention, the vertical transistor manufacturing method of the present invention, and the gate-all-around transistor manufacturing method of the present invention have excellent selective solubility in the 110 plane of a silicon crystal relative to the 100 plane of a silicon crystal in the etching step, and therefore can perform highly accurate etching and produce desired products with a high yield.

[0014] The present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be practiced with various modifications within the scope of the gist. In this specification, when the expression "to" is used, it is used as an expression including the numerical values ​​or physical property values ​​before and after it.

[0015] In a first aspect, the etching solution of the present invention contains an alkaline compound (A) and at least one compound (B) selected from the group consisting of an oxidizing agent (B1) and a cationic surfactant (B2) (hereinafter sometimes referred to as "component (B)"), thereby exhibiting excellent selective dissolution of the 110 face of a silicon crystal relative to the 100 face of a silicon crystal. The etching solution of the present invention preferably further contains water (hereinafter sometimes referred to as "component (C)"). The reason why the etching solution of the present invention exhibits excellent selective dissolution of the 110 face of a silicon crystal relative to the 100 face of a silicon crystal is thought to be as follows: When a silicon crystal is etched using the etching solution of the present invention, the silicon is dissolved by component (A) and is partially oxidized by component (B1) to form silicon oxide. The dissolution rate of silicon by component (A) depends on the surface proportion of partially oxidized silicon oxide, and is slower as the surface proportion of silicon oxide increases. Meanwhile, partial oxidation of silicon by component (B1) is more likely to occur on the 100 face of a silicon crystal than on the 110 face of a silicon crystal. As a result, it is believed that the etching solution of the present invention has excellent selective solubility for the 110 plane of silicon crystal relative to the 100 plane of silicon crystal. Furthermore, component (B2) adsorbs and protects Si—OH on the surface of the silicon crystal through ionic bonds, thereby suppressing silicon dissolution. Component (B2) adsorbs and protects the surface of the silicon crystal more easily for the 100 plane than for the 110 plane. Component (B2) accelerates silicon dissolution more easily for the 110 plane than for the 100 plane. As a result, it is believed that the etching solution of the present invention has excellent selective solubility for the 110 plane of silicon crystal relative to the 100 plane of silicon crystal.

[0016] In a second aspect, the etching solution of the present invention contains, as component (A), an alkylammonium hydroxide (A1) having an alkyl group having 10 or more carbon atoms (hereinafter, sometimes referred to as "component (A1)"), and thereby exhibits excellent selective solubility of the 110 plane of a silicon crystal relative to the 100 plane of a silicon crystal. The etching solution of the present invention preferably further contains water (hereinafter, sometimes referred to as "component (C)"). The reason why the etching solution of the present invention exhibits excellent selective solubility of the 110 plane of a silicon crystal relative to the 100 plane of a silicon crystal is thought to be as follows. When a silicon crystal is etched using the etching solution of the present invention, component (A1) dissolves the silicon and also adsorbs and protects the surface of the silicon crystal. Component (A1) more easily adsorbs and protects the surface of the silicon crystal for the 100 plane than for the 110 plane. As a result, it is thought that the etching solution of the present invention exhibits excellent selective solubility of the 110 plane of a silicon crystal relative to the 100 plane of a silicon crystal. The first aspect will now be described.

[0017] [First Aspect] (Component (A)) The component (A) is an alkaline compound (A). When the etching liquid of the present invention contains the alkaline compound (A), it has excellent silicon solubility.

[0018] Examples of component (A) include organic alkali compounds such as quaternary ammonium hydroxide compounds, such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide; and inorganic alkali compounds such as metal hydroxides, such as sodium hydroxide, potassium hydroxide, and calcium hydroxide. These components (A) may be used alone or in combination of two or more. Among these components (A), quaternary ammonium hydroxide compounds, potassium hydroxide, and calcium hydroxide are preferred because they have a low content of sodium, which is likely to affect transistor performance; quaternary ammonium hydroxide compounds are more preferred, and tetramethylammonium hydroxide and tetrabutylammonium hydroxide are even more preferred.

[0019] The content of component (A) is preferably 0.1 mass% or more, more preferably 0.2 mass% or more, and even more preferably 0.5 mass% or more, based on 100 mass% of the etching solution, because of its excellent solubility in silicon. The content of component (A) is preferably 39.99 mass% or less, more preferably 34.95 mass% or less, and even more preferably 29.92 mass% or less, based on 100 mass% of the etching solution, because of its excellent solubility in water.

[0020] (Compound (B)) Compound (B) is at least one selected from the group consisting of an oxidizing agent (B1) and a cationic surfactant (B2). When the etching solution of the present invention contains an oxidizing agent (B1), the partial oxidation of silicon is promoted. Furthermore, when the etching solution of the present invention contains the cationic surfactant (B2) of the present invention, the etching solution of the present invention exhibits excellent selective adsorption of the 100 plane and selective solubility of the 110 plane of silicon crystal.

[0021] (Oxidizing Agent (B1)) Examples of the oxidizing agent (B1) include hydrogen peroxide, peroxodisulfuric acid or a salt thereof, chlorous acid or a salt thereof, bromic acid or a salt thereof, chromic acid or a salt thereof, perchloric acid or a salt thereof, and nitric acid or a salt thereof. These components (B1) may be used alone or in combination of two or more. Among these components (B1), hydrogen peroxide, peroxodisulfuric acid or a salt thereof, and chromic acid or a salt thereof are preferred because they produce fewer hazardous reaction products, hydrogen peroxide, peroxodisulfuric acid or a salt thereof are more preferred, and hydrogen peroxide is even more preferred.

[0022] The content of the oxidizing agent (B1) is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, and even more preferably 0.08 mass% or more, relative to 100 mass% of the etching solution, in order to promote partial oxidation of silicon. The content of the oxidizing agent (B1) is preferably 5 mass% or less, more preferably 3 mass% or less, and even more preferably 2 mass% or less, relative to 100 mass% of the etching solution, in order to suppress complete oxidation of silicon.

[0023] (Cationic Surfactant (B2)) The cationic surfactant (B2) is preferably a quaternary ammonium compound, more preferably an alkyl group-containing quaternary ammonium compound, a pyridinium ring-containing quaternary ammonium compound, a pyrrolidinium ring-containing quaternary ammonium compound, or a piperidinium ring-containing quaternary ammonium compound, and even more preferably an alkyl group-containing quaternary ammonium compound. Note that the cationic surfactant (B2) does not contain the alkaline compound (A).

[0024] Examples of cationic surfactants (B2) include hexadecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, didecyldimethylammonium bromide, dioctadecyldimethylammonium bromide, tetrabutylammonium bromide, tetradecylammonium bromide, benzyldimethylstearylammonium chloride, hexadecylpyridinium chloride, and 1-methyl-1-octylpyrrolidinium chloride. These components (B2) may be used alone or in combination of two or more. Among these components (B2), hexadecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, and didecyldimethylammonium bromide are preferred due to their excellent solubility in water, with hexadecyltrimethylammonium bromide and octadecyltrimethylammonium bromide being more preferred, and hexadecyltrimethylammonium bromide being even more preferred.

[0025] The content of the cationic surfactant (B2) is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, and even more preferably 0.08 mass% or more, based on 100 mass% of the etching solution, because it has excellent selective adsorption properties for the 100-plane of silicon crystals and selective solubility for the 110-plane. The content of the component (B2) is preferably 5 mass% or less, more preferably 3 mass% or less, even more preferably 2 mass% or less, and particularly preferably 1 mass% or less, based on 100 mass% of the etching solution, because it has excellent solubility in water.

[0026] (Component (C)) The etching solution of the present invention preferably contains water (component (C)) in addition to the components (A) and (B).

[0027] The content of component (C) is preferably 60% by mass or more, more preferably 65% ​​by mass or more, and even more preferably 70% by mass or more, based on 100% by mass of the etching solution, because the etching solution is easy to produce and the solubility of components (A) and (B) is excellent. The content of component (C) is preferably 99.5% by mass or less, more preferably 98% by mass or less, and even more preferably 95% by mass or less, based on 100% by mass of the etching solution, because the solubility of silicon is excellent.

[0028] (Other Components) The etching solution of the present invention may contain other components in addition to component (A), component (B), and component (C) as long as the effects of the present invention are not impaired. However, there may be cases where the etching solution does not contain any components other than component (A), component (B), and component (C). For example, the content of the other components may be 0.001% by mass or less in 100% by mass of the etching solution. In other cases, the etching solution may be substantially free of other components. An etching solution that is substantially free of other components means that the content of the other components in 100% by mass of the etching solution is 0% by mass to 0.00001% by mass. Examples of other components that may be contained include chelating agents, water-miscible solvents, thiol compounds, nonionic surfactants, cationic surfactants, and anionic surfactants.

[0029] The etching solution of the present invention contains a chelating agent, which exerts a chelating effect of adsorption to each crystal face of silicon.

[0030] Examples of chelating agents include amine compounds, amino acids, and organic acids. 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 because of their excellent chelating effect, and amine compounds are more preferred.

[0031] 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. 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 of their excellent chelating effect, 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.

[0032] Examples of amino acids include glycine, arginine, histidine, and (2-dihydroxyethyl)glycine. These amino acids may be used alone or in combination of two or more. Among these amino acids, glycine, arginine, histidine, and (2-dihydroxyethyl)glycine are preferred, and (2-dihydroxyethyl)glycine is more preferred, due to their excellent chelating effect.

[0033] 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 alone or in combination of two or more. Among these organic acids, oxalic acid, citric acid, tartaric acid, malic acid, and 2-phosphonobutane-1,2,4-tricarboxylic acid are preferred because of their excellent chelating effect, and citric acid and 2-phosphonobutane-1,2,4-tricarboxylic acid are more preferred.

[0034] When the etching solution of the present invention contains a chelating agent, the content of the chelating agent 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, relative to 100% by mass of the etching solution, because the chelating effect is excellent. When the etching solution of the present invention contains a chelating agent, the content of the chelating agent is preferably 25% by mass or less, more preferably 10% by mass or less, and even more preferably 6% by mass or less, relative to 100% by mass of the etching solution, because the solubility in water is excellent.

[0035] The etching solution of the present invention contains a water-miscible solvent, which has the effect of making a hydrophobic substance that is not miscible with water miscible with water.

[0036] The water-miscible solvent may be any solvent that has excellent solubility in water, and may have a solubility parameter (SP value) of 7.0 (cal / cm ３ ) １／２ A solvent of 9.0 (cal / cm ３ ) １／２ The above solvents are more preferred.

[0037] Examples of water-miscible solvents include polar protic solvents such as isopropanol, ethylene glycol, propylene glycol, methanol, ethanol, propanol, butanol, glycerol, and 2-(2-aminoethoxy)ethanol; 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.

[0038] When the etching liquid of the present invention contains a water-miscible solvent, the content of the water-miscible solvent is preferably 5% by mass or less, more preferably 1% by mass or less, based on 100% by mass of the etching liquid, and most preferably does not contain a water-miscible solvent.

[0039] (Mass Ratio of Each Component) The mass ratio of component (B) to component (A) in the etching solution of the present invention (mass of component (B) / mass of component (A), hereinafter referred to as "(B) / (A)") is preferably 2 or less, more preferably 1 or less, and even more preferably 0.5 or less, because in the case of the oxidizing agent (B1), an excellent balance between silicon solubility and partial oxidation of silicon is achieved, and in the case of the cationic surfactant (B2), an excellent balance between silicon solubility and selective adsorption of the (100) face of silicon crystals is achieved. From the same viewpoint, it is preferably 0.003 or more, more preferably 0.005 or more, and even more preferably 0.01 or more. It is also preferably 0.003 to 2, more preferably 0.005 to 1, and even more preferably 0.01 to 0.5.

[0040] When the etching solution of the present invention contains component (C), the mass ratio of component (A) to component (C) (mass of component (A) / mass of component (C), hereinafter referred to as "(A) / (C)") is preferably 0.001 to 0.7, more preferably 0.003 to 0.6, and even more preferably 0.005 to 0.5, in view of excellent silicon solubility.

[0041] When the etching solution of the present invention contains component (C), the mass ratio of component (B) to component (C) (mass of component (B) / mass of component (C), hereinafter referred to as "(B) / (C)") is preferably 0.0001 to 0.08, more preferably 0.0005 to 0.03, and even more preferably 0.001 to 0.01, because the oxidizing agent (B1) provides excellent partial oxidation of silicon, and the cationic surfactant (B2) provides excellent selective adsorption of the 100 plane and selective dissolution of the 110 plane of silicon crystal. Next, a second aspect will be described.

[0042] [Second Aspect] (Component (A1)) Component (A1) is an alkylammonium hydroxide (A1) having an alkyl group having 10 or more carbon atoms. When the etching solution of the present invention contains alkylammonium hydroxide (A1) having an alkyl group having 10 or more carbon atoms, it exhibits excellent selective adsorption of the 100-face of silicon crystal.

[0043] Component (A1) is preferably an alkylammonium hydroxide having an alkyl group with 12 to 20 carbon atoms, and more preferably an alkylammonium hydroxide having an alkyl group with 14 to 18 carbon atoms, because these have excellent adsorption stability on the silicon crystal surface.

[0044] Examples of component (A1) include hexadecyltrimethylammonium hydroxide, octadecyltrimethylammonium hydroxide, didodecyldimethylammonium hydroxide, and tetradecylammonium hydroxide. These components (A1) may be used alone or in combination of two or more. Among these components (A1), hexadecyltrimethylammonium hydroxide, octadecyltrimethylammonium hydroxide, and didodecyldimethylammonium hydroxide are preferred because of their excellent solubility in water, with hexadecyltrimethylammonium hydroxide and octadecyltrimethylammonium hydroxide being more preferred, and hexadecyltrimethylammonium hydroxide being even more preferred.

[0045] The content of component (A1) is preferably 0.1 mass% or more, more preferably 0.2 mass% or more, and even more preferably 0.5 mass% or more, based on 100 mass% of the etching solution, because of its excellent solubility in silicon. The content of component (A1) is preferably 40 mass% or less, more preferably 35 mass% or less, and even more preferably 30 mass% or less, based on 100 mass% of the etching solution, because of its excellent solubility in water.

[0046] (Component (C)) The etching solution of the present invention preferably contains water (component (C)) in addition to the component (A1).

[0047] The content of component (C) is preferably 60% by mass or more, more preferably 65% ​​by mass or more, and even more preferably 70% by mass or more, based on 100% by mass of the etching solution, because the etching solution is easy to produce and the solubility of component (A1) is excellent. The content of component (C) is preferably 99.9% by mass or less, more preferably 99.8% by mass or less, and even more preferably 99.5% by mass or less, based on 100% by mass of the etching solution, because the solubility of silicon is excellent.

[0048] (Other Components) The etching solution of the present invention may contain other components in addition to component (A1) and component (C) as long as the effects of the present invention are not impaired. However, the etching solution may not contain any other components other than component (A1) and component (C). For example, the content of the other components may be 0.001% by mass or less in 100% by mass of the etching solution. In other cases, the etching solution may be substantially free of other components. An etching solution that is substantially free of other components means that the content of the other components in 100% by mass of the etching solution is 0% by mass to 0.00001% by mass. Examples of other components that may be contained include chelating agents, water-miscible solvents, oxidizing agents, thiol compounds, nonionic surfactants, cationic surfactants, and anionic surfactants.

[0049] The etching solution of the present invention contains a chelating agent, which exerts a chelating effect of adsorption to each crystal face of silicon.

[0050] Examples of chelating agents include amine compounds, amino acids, and organic acids. 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 chelating effects. Examples of the chelating agent include the same ones as those described in the first embodiment.

[0051] When the etching solution of the present invention contains a chelating agent, the content of the chelating agent 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, relative to 100% by mass of the etching solution, because the chelating effect is excellent. When the etching solution of the present invention contains a chelating agent, the content of the chelating agent is preferably 25% by mass or less, more preferably 10% by mass or less, and even more preferably 6% by mass or less, relative to 100% by mass of the etching solution, because the solubility in water is excellent.

[0052] The etching solution of the present invention contains a water-miscible solvent, which has the effect of making a hydrophobic substance that is not miscible with water miscible with water. Examples of the water-miscible solvent include those described in the first embodiment, and the solvent is used in the same manner and at the same content as those described in the first embodiment.

[0053] (Mass Ratio of Each Component) When the etching liquid of the present invention contains component (C), the mass ratio of component (A1) to component (C) (mass of component (A1) / mass of component (C), hereinafter referred to as "(A1) / (C)") is preferably 0.001 to 0.7, more preferably 0.003 to 0.6, and even more preferably 0.005 to 0.5, in order to achieve excellent silicon solubility.

[0054] (Method for Producing Etching Solution) The method for producing the etching solution of the first aspect of the present invention is not particularly limited, and the etching solution can be produced by mixing component (A), component (B), and, if necessary, component (C), and other components. Furthermore, the method for producing the etching solution of the second aspect of the present invention is not particularly limited, and the etching solution can be produced by mixing component (A1), and, if necessary, component (C), 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.

[0055] (Physical Properties of Etching Solution) The pH of the etching solution of the present invention is preferably 8 to 14, more preferably 9 to 14, and even more preferably 10 to 14, in view of excellent silicon solubility.

[0056] Etching rate ER for the 110 plane of silicon crystal １１０In the first embodiment, when an etching solution containing an oxidizing agent (B1) is used as the compound (B), the etching rate ER for the (110) plane of the silicon crystal is preferably 1 nm / min or more, more preferably 1.5 nm / min or more, and even more preferably 2 nm / min or more, because this provides excellent efficiency in forming nano-shapes in the horizontal direction. １１０ In the first embodiment, when an etching solution containing a cationic surfactant (B2) as the compound (B) is used, the etching rate ER for the (110) plane of the silicon crystal is preferably 10 nm / min or more, more preferably 20 nm / min or more, and even more preferably 30 nm / min or more, because the efficiency of forming nano-shapes in the horizontal direction is excellent. １１０ In the second embodiment, the rate is preferably 10 nm / min or more, more preferably 50 nm / min or more, and even more preferably 100 nm / min or more, because this provides excellent efficiency in forming nano-shapes in the horizontal direction.

[0057] Etching rate ER for the 100 plane of silicon crystal １００ In the first embodiment, when an etching solution containing an oxidizing agent (B1) is used as the compound (B), the etching rate ER for the (100) plane of the silicon crystal is preferably 50 nm / min or less, more preferably 30 nm / min or less, and even more preferably 10 nm / min or less, because the efficiency of forming nano-shapes in the horizontal direction is excellent. １００ In the first embodiment, when an etching solution containing a cationic surfactant (B2) as the compound (B) is used, the etching rate ER for the (100) plane of the silicon crystal is preferably 200 nm / min or less, more preferably 100 nm / min or less, and even more preferably 50 nm / min or less, because the efficiency of forming nano-shapes in the horizontal direction is excellent. １００ In the second embodiment, the rate is preferably 300 nm / min or less, more preferably 200 nm / min or less, and even more preferably 100 nm / min or less, because this provides excellent efficiency in forming nano-shapes in the horizontal direction.

[0058] Etching rate ER for the 111 plane of silicon crystal １１１In the first aspect, when an etching solution containing an oxidizing agent (B1) as the compound (B) is used, the etching rate is preferably 0.5 nm / min or more, more preferably 1.0 nm / min or more, and even more preferably 1.5 nm / min or more, because this is excellent in forming a flat facet of the 110 plane of the silicon crystal.

[0059] Preferential solubility of the 110 face of silicon crystal relative to the 100 face of silicon crystal (ER １１０ / ER １００ ) is greater than 1, preferably 1.1 to 10, more preferably 1.2 to 7, and even more preferably 1.3 to 5, because the melt processability of the silicon crystal in the horizontal direction is excellent in the first and second aspects.

[0060] Preferential solubility of the 111 plane of silicon crystal relative to the 110 plane of silicon crystal (ER １１１ / ER １１０ In the first aspect, when an etching solution containing an oxidizing agent (B1) is used as the compound (B), the ρ is preferably 0.3 or more, more preferably 0.4 to 5, and even more preferably 0.5 to 3, since excellent flatness of the (110) plane of the silicon crystal is obtained.

[0061] In this specification, the etching rate and selective solubility are measured by the method described in the examples below.

[0062] (Subject to be etched by etching solution) The etching solution of the present invention has excellent selective solubility for the 110 face of a silicon crystal relative to the 100 face of a silicon crystal, and is therefore suitable as an etching solution for dissolving silicon, and is particularly suitable as an etching solution for dissolving the 110 face of a silicon crystal relative to the 100 face of a silicon crystal.

[0063] The silicon to be etched is preferably single crystal silicon because it has a crystal plane orientation. Single crystal silicon can be produced by a known method, and may be produced by cutting out a single crystal ingot or by epitaxial growth.

[0064] (Etching Method) The etching method of the present invention is a method of etching a silicon-containing structure using the etching solution of the present invention.

[0065] The silicon in the silicon-containing structure has a crystal plane orientation, and is therefore preferably single-crystal silicon. Single-crystal silicon can be produced by a known method, and may be produced by cutting out a single-crystal ingot or by epitaxial growth.

[0066] The silicon-containing structure may also contain a material other than silicon, such as silicon germanium, silicon oxide, silicon nitride, or silicon carbonitride.

[0067] The etching method may be a known method, such as a batch method or a single wafer method.

[0068] 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 lower, more preferably 80° C. or lower, since this can suppress damage to the substrate and provide excellent etching stability. The temperature during etching corresponds to the temperature of the etching solution during etching.

[0069] (Uses) The etching solution of the present invention is suitable as an etching solution for dissolving silicon, because it has excellent selective solubility for the 110 plane of a silicon crystal relative to the 100 plane of a silicon crystal, and is particularly suitable as an etching solution for dissolving the 110 plane of a silicon crystal relative to the 100 plane of a silicon crystal. Therefore, the etching solution of the present invention is suitable for etching semiconductor devices having silicon-containing structures, and is more suitable for vertical transistors having silicon-containing structures and gate-all-around transistors having silicon-containing structures, and is particularly suitable for vertical transistors having silicon-containing structures.

[0070] The present invention will be explained in more detail below using examples, but the present invention is not limited to the description of the following examples as long as it does not deviate from the gist of the invention.

[0071] (Preferential solubility of the 110 plane of silicon crystal relative to the 100 plane of silicon crystal) A silicon substrate having silicon crystals with a plane orientation of the 110 plane and the 100 plane was immersed in a 0.5 mass % aqueous solution of hydrofluoric acid for 3 minutes, and then rinsed with ultrapure water. Thereafter, the back surface of the silicon substrate was masked, and the silicon substrate was immersed in the etching solution obtained in the Examples and Comparative Examples at 60°C for 10 to 60 minutes. The film thickness of the silicon substrate before and after immersion was measured with a spectral interference film thickness meter, and the selective solubility of the 110 plane of silicon crystal relative to the 100 plane of silicon crystal was calculated using the following formulas (1) to (3). ER １１０ [nm / min] = (film thickness of silicon substrate before immersion [nm] - film thickness of silicon substrate after immersion [nm]) ÷ (immersion time [min]) (1) ER １００ [nm / min] = (film thickness of silicon substrate before immersion [nm] - film thickness of silicon substrate after immersion [nm]) ÷ (immersion time [min]) (2) Selective solubility = ER １１０ [nm / min]÷ER １００ [nm / min] (3)

[0072] (Preferential solubility of the 111 plane of silicon crystal relative to the 110 plane of silicon crystal) A silicon substrate having silicon crystals with a plane orientation of 111 and 110 was immersed in a 0.5 mass % aqueous solution of hydrofluoric acid for 3 minutes, and then rinsed with ultrapure water. The back surface of the silicon substrate was then masked, and the silicon substrate was immersed in the etching solutions obtained in the Examples and Comparative Examples at 60°C for 10 to 60 minutes. The film thickness of the silicon substrate before and after immersion was measured with a spectral interference film thickness meter, and the selective solubility of the 111 plane of silicon crystal relative to the 110 plane of silicon crystal was calculated using the following equations (4) to (6). ER １１１ [nm / min] = (film thickness of silicon substrate before immersion [nm] - film thickness of silicon substrate after immersion [nm]) ÷ (immersion time [min]) (4) ER １１０ [nm / min] = (film thickness of silicon substrate before immersion [nm] - film thickness of silicon substrate after immersion [nm]) ÷ (immersion time [min]) (5) Selective solubility = ER １１１ [nm / min]÷ER １１０ [nm / min] (6)

[0073] (Raw Materials) The following were used as raw materials for producing the etching solutions in the Examples and Comparative Examples: Component (A-1): potassium hydroxide Component (A-2): tetramethylammonium hydroxide Component (A-3): tetrabutylammonium hydroxide Component (B1-1): hydrogen peroxide

[0074] [Example 1-1] The components were mixed so that, based on 100 mass% of the etching solution, 0.56 mass% of component (A-1), 0.10 mass% of component (B1-1), and the remainder was water, and the components were bubbled with nitrogen gas for 5 minutes to obtain an etching solution. The evaluation results of the obtained etching solution are shown in Table 1.

[0075] Examples 1-2 to 1-4 Etching solutions were obtained in the same manner as in Example 1-1, except that the types and contents of the components of the etching solutions were changed as shown in Table 1. The evaluation results of the obtained etching solutions are shown in Table 1.

[0076] [Comparative Examples 1-1 and 1-2] Etching solutions were obtained in the same manner as in Example 1-1, except that the types and contents of the components of the etching solution were changed as shown in Table 1. The evaluation results of the obtained etching solutions are shown in Table 1.

[0077]

[0078] As can be seen from Table 1, the etching solutions obtained in the Examples were remarkably superior in selective dissolution of the 110 plane of silicon crystal relative to the 100 plane of silicon crystal, and also improved in selective dissolution of the 111 plane of silicon crystal relative to the 110 plane of silicon crystal. On the other hand, the etching solutions obtained in the Comparative Examples were inferior in selective dissolution of the 110 plane of silicon crystal relative to the 100 plane of silicon crystal and in selective dissolution of the 111 plane of silicon crystal relative to the 110 plane of silicon crystal.

[0079] (Raw Materials) The following were used as raw materials for producing the etching solutions in the Examples and Comparative Examples. Component (A-1): Potassium hydroxide Component (A-2): Tetramethylammonium hydroxide Component (A-3): Tetrabutylammonium hydroxide Component (B2-1): Hexadecyltrimethylammonium bromide Component (B2-2): Octadecyltrimethylammonium bromide Component (B2-3): Didecyldimethylammonium bromide Component (B2-4): Dioctadecyldimethylammonium bromide

[0080] [Example 2-1] The etching solution was mixed so that, based on 100 mass%, the component (A-1) was 0.56 mass%, the component (B2-1) was 1.0 mass%, and water was the remainder, and the components were mixed and bubbled with nitrogen gas for 5 minutes to obtain an etching solution. The evaluation results of the obtained etching solution are shown in Table 2.

[0081] Examples 2-2 to 2-8 Etching solutions were obtained in the same manner as in Example 2-1, except that the types and contents of the components of the etching solutions were changed as shown in Table 2. The evaluation results of the obtained etching solutions are shown in Table 2.

[0082] Comparative Example 2-1 Etching solutions were obtained in the same manner as in Example 2-1, except that the types and contents of the components of the etching solution were changed as shown in Table 2. The evaluation results of the obtained etching solutions are shown in Table 2.

[0083]

[0084] As can be seen from Table 2, the etching solutions obtained in the Examples were remarkably superior in selective dissolution of the 110 plane of silicon crystal relative to the 100 plane of silicon crystal, whereas the etching solutions obtained in the Comparative Examples were inferior in selective dissolution of the 110 plane of silicon crystal relative to the 100 plane of silicon crystal.

[0085] (Raw Materials) The following were used as raw materials for producing the etching solutions in the Examples and Comparative Examples: Component (A1-1): hexadecyltrimethylammonium hydroxide Component (A'-1): potassium hydroxide Component (A'-2): tetramethylammonium hydroxide

[0086] [Example 3-1] The components were mixed so that the component (A1-1) was 3.02 mass% and water was the remainder in 100 mass% of the etching solution, and the components were bubbled with nitrogen gas for 5 minutes to obtain an etching solution. The evaluation results of the obtained etching solution are shown in Table 3.

[0087] Etching solutions were obtained in the same manner as in Example 3-1, except that the types and contents of the components of the etching solution were changed as shown in Table 3. The evaluation results of the obtained etching solutions are shown in Table 3.

[0088]

[0089] As can be seen from Table 3, the etching solutions obtained in the Examples were remarkably superior in selective dissolution of the 110 plane of silicon crystal relative to the 100 plane of silicon crystal, whereas the etching solutions obtained in the Comparative Examples were inferior in selective dissolution of the 110 plane of silicon crystal relative to the 100 plane of silicon crystal.

[0090] The etching solution of the present invention is suitable as an etching solution for dissolving silicon, because it has excellent selective solubility for the 110 plane of a silicon crystal relative to the 100 plane of a silicon crystal, and is particularly suitable as an etching solution for dissolving the 110 plane of a silicon crystal relative to the 100 plane of a silicon crystal. Therefore, the etching solution of the present invention is suitable for etching semiconductor devices having silicon-containing structures, and is more suitable for vertical transistors having silicon-containing structures and gate-all-around transistors having silicon-containing structures, and is particularly suitable for vertical transistors having silicon-containing structures.

Claims

1. An ER comprising an alkaline compound (A) and at least one compound (B) selected from the group consisting of an oxidizing agent (B1) and a cationic surfactant (B2). １１０ / ER １００ >1. １１０ is the etching rate for the 110 plane of the silicon crystal, and the ER １００ is the etching rate for the 100 plane of a silicon crystal.) 2. The etching solution according to claim 1, wherein the alkaline compound (A) comprises at least one compound selected from the group consisting of quaternary ammonium hydroxide compounds, potassium hydroxide and calcium hydroxide.

3. The etching solution according to claim 1, wherein the oxidizing agent (B1) comprises hydrogen peroxide.

4. The etching solution according to claim 1, wherein the cationic surfactant (B2) comprises a quaternary ammonium compound.

5. The etching solution according to claim 1, wherein the cationic surfactant (B2) comprises at least one compound selected from the group consisting of an alkyl group-containing quaternary ammonium compound, a pyridinium ring-containing quaternary ammonium compound, a pyrrolidinium ring-containing quaternary ammonium compound, and a piperidinium ring-containing quaternary ammonium compound.

6. The etching solution of claim 1, further comprising water.

7. The etching solution according to claim 6, wherein the water content in 100% by mass of the etching solution is 60% by mass or more.

8. The etching solution according to claim 1, wherein the content of the alkaline compound (A) in 100% by mass of the etching solution is 0.1% by mass to 39.99% by mass.

9. The etching solution according to claim 1, wherein the content of compound (B) in 100% by mass of the etching solution is 0.01% by mass to 5% by mass.

10. The etching solution according to claim 1, wherein the ratio of the mass of the compound (B) to the mass of the alkaline compound (A) is 0.001 to 2.

11. ER １１１ / ER １１０ 3. The etching solution according to claim 1, wherein the ER is ≧0.

3. １１１ is the etching rate for the 111 plane of silicon crystal.) 12. The etching solution according to claim 1, which is used as an etching solution for dissolving silicon.

13. The etching solution according to claim 1, which dissolves the 110 faces of silicon crystals relative to the 100 faces of silicon crystals.

14. The etching solution of claim 1, wherein the silicon is single crystal silicon.

15. An etching method comprising etching a silicon-containing structure using the etching solution according to any one of claims 1 to 14.

16. A method for manufacturing a semiconductor device, comprising the step of etching a silicon-containing structure using the etching solution according to any one of claims 1 to 14.

17. A method for manufacturing a vertical transistor, comprising the step of etching a silicon-containing structure with the etching solution according to any one of claims 1 to 14.

18. A method for manufacturing a gate-all-around transistor, comprising the step of etching a silicon-containing structure with the etching solution according to any one of claims 1 to 14.

19. A method for etching a silicon-containing structure, comprising the step of selectively etching a (110) face of a silicon crystal relative to a (100) face of a silicon crystal using an etching solution containing an alkaline compound (A) and at least one compound (B) selected from the group consisting of an oxidizing agent (B1) and a cationic surfactant (B2).

20. A method for manufacturing a semiconductor device, comprising a step of selectively etching a (110) face of a silicon crystal relative to a (100) face of a silicon crystal using an etching solution containing an alkaline compound (A) and at least one compound (B) selected from the group consisting of an oxidizing agent (B1) and a cationic surfactant (B2).

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