Etching composition, etching method, method for manufacturing semiconductor device, and method for manufacturing transistor

Abstract

The present invention addresses the problem of providing: an etching composition that has exceptional selective silicon solubility with respect to silicon germanium and / or an etching composition that has exceptional flatness; and an etching method, a method for manufacturing a semiconductor device, and a method for manufacturing a transistor in which the etching composition is used.　The present invention discloses an etching composition according to first to fourth aspects as an etching composition for addressing the aforementioned problem.　For example, exemplified as one aspect for addressing the problem is an etching composition according to the first aspect, the etching composition containing a quaternary ammonium compound (A1) having less than 13 carbon atoms, an organic reducing agent (B1), and a quaternary ammonium compound (D1) having 13 or more carbon atoms, the etching composition being such that the content mass ratio ((D1) / (A1)) of the compound (D1) to the compound (A1) is 0.05 or less, and silicon is selectively dissolved in silicon germanium.

Description

Etching composition, etching method, semiconductor device manufacturing method, and transistor manufacturing method

[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 transistor.

[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 transistor performance per unit area.

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

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

[0007] In recent years, a structure called backside power delivery network (BSPDN) has been investigated to achieve even finer integration. In conventional transistors, a wiring network for supplying power is formed on top of the transistor. However, as integration density increases, these wiring networks have become an obstacle to increasing the transistor integration density per unit area. For this reason, the BSPDN structure aims to increase integration density by supplying power from the backside.

[0008] The BSPDN manufacturing process includes bonding a silicon wafer with a device surface to another silicon wafer, and then etching and thinning the silicon layer of the wafer on the side opposite the device surface using an etching composition. During this process, a SiGe layer is previously formed as a stop layer to stop the etching. In the final etching stage, the SiGe layer exposed on the surface by etching functions as an etch stop layer against the etching composition, thereby achieving a flat SiGe surface over a wide area of ​​the wafer. An etching composition capable of achieving this is therefore required. Therefore, in the manufacture of BSPDN, an etching composition with excellent selective solubility of silicon (Si) relative to silicon germanium (SiGe) is required. In another aspect, an etching composition capable of etching a wide area smoothly (hereinafter sometimes referred to as "excellent flatness") is required to increase productivity in the etching process after thinning the silicon layer. In yet another aspect, an etching composition with excellent selective solubility of silicon relative to silicon germanium and excellent flatness is required.

[0009] The present invention has been made in view of these problems, and an object of the present invention is to provide an etching composition that has excellent selective solubility of silicon relative to silicon germanium. In another aspect, an object of the present invention is to provide an etching composition that has excellent flatness. In yet another aspect, an object of the present invention is to provide an etching composition that has excellent selective solubility of silicon relative to silicon germanium and also has excellent flatness. Another object of the present invention is to provide an etching method, a method for manufacturing a semiconductor device, and a method for manufacturing a transistor using the etching composition.

[0010] As a result of extensive research, the present inventors have found that, as a first aspect, an etching composition comprising a quaternary ammonium compound (A1) having less than 13 carbon atoms, an organic reducing agent (B1), and a quaternary ammonium compound (D1) having 13 or more carbon atoms, wherein the mass ratio of the compound (D1) to the compound (A1) ((D1) / (A1)) is 0.05 or less, and which selectively dissolves silicon relative to silicon germanium, exhibits excellent selective solubility of silicon relative to silicon germanium and excellent flatness. Furthermore, as a second aspect, the present inventors have found that an etching composition comprising an alkaline compound (A2), an organic reducing agent (B2) (excluding a thiol compound (D2)), and a thiol compound (D2), wherein the mass ratio of the thiol compound (D2) to the alkaline compound (A2) ((D2) / (A2)) is 0.50 or less, and which selectively dissolves silicon relative to silicon germanium, exhibits excellent selective solubility of silicon relative to silicon germanium. Furthermore, as a third aspect, an etching composition containing an alkaline compound (A3) and an organic reducing agent (B3) dissolves a Si(100) surface such that, when etched at 60°C for 5 minutes, the average surface roughness measured on three parallel 1 mm line segments spaced 0.5 cm apart on the surface is 80 nm or less. It was also found that this etching composition exhibits excellent selective solubility of silicon relative to silicon germanium and excellent flatness. Additionally, as a fourth aspect, an etching composition containing an alkaline compound (A4) and an inorganic reducing agent (B4) selectively dissolves silicon relative to silicon germanium. Based on these findings, the present invention has been completed.

[0011] That is, the gist of the present invention is as follows. [1] An etching composition comprising a quaternary ammonium compound (A1) having less than 13 carbon atoms, an organic reducing agent (B1), and a quaternary ammonium compound (D1) having 13 or more carbon atoms, wherein the mass ratio of the compound (D1) to the compound (A1) ((D1) / (A1)) is 0.05 or less, and wherein silicon is selectively dissolved relative to silicon germanium. [2] The etching composition according to [1], wherein the organic reducing agent (B1) comprises a reducing sugar. [3] The etching composition according to [1] or [2], wherein the compound (D1) comprises a quaternary ammonium compound all of whose alkyl groups are the same. [4] The etching composition according to any one of [1] to [3], further comprising water (C1). [5] The etching composition according to any one of [1] to [4], further comprising a water-miscible solvent. [6] The etching composition according to any one of [1] to [5], wherein the content of the compound (D1) in 100 mass% of the etching composition is less than 1 mass% (but not including 0). [7] The etching composition according to [4], wherein the content of water (C1) in 100 mass% of the etching composition is 60 mass% or more. [8] The etching rate ER for silicon at 60°C Ｓｉ１ and the etching rate ER for silicon germanium ＳｉＧｅ１ The etching composition according to any one of [1] to [7], wherein ER satisfies the following formula (1): Ｓｉ１ / ER ＳｉＧｅ１ ≧35 (1) [9] The etching composition according to any one of [1] to [8], which is used as an etching composition for dissolving silicon.

[10] The etching composition according to any one of [1] to [9], which dissolves a Si(100) surface after etching at 60°C for 5 minutes, so that the average surface roughness measured on three 1 mm long lines arranged parallel to each other at 0.5 cm intervals on the surface is 80 nm or less.

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

[10] .

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

[10] , which dissolves a silicon-containing structure after etching at 60°C for 5 minutes, so that the average surface roughness measured on three 1 mm long lines arranged parallel to each other at 0.5 cm intervals on the surface is 80 nm or less. ２

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

[10] .

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

[10] .

[15] A method for manufacturing a transistor according to

[14] , wherein the silicon surface is a surface on the Si layer side in a stack of a SiGe layer and a Si layer.

[16] A method for manufacturing a transistor having a BSPDN structure, comprising a step of etching a silicon-containing structure using the etching composition according to any one of [1] to

[10] .

[17] An etching method comprising using a composition containing a quaternary ammonium compound (A1) having less than 13 carbon atoms, an organic reducing agent (B1), and a quaternary ammonium compound (D1) having 13 or more carbon atoms, wherein the mass ratio of the content of the compound (D1) to the content of the compound (A1) ((D1) / (A1)) is 0.05 or less, in etching to selectively dissolve silicon relative to silicon germanium.

[18] Use of a composition containing a quaternary ammonium compound (A1) having less than 13 carbon atoms, an organic reducing agent (B1), and a quaternary ammonium compound (D1) having 13 or more carbon atoms, wherein the mass ratio of the content of the compound (D1) to the content of the compound (A1) ((D1) / (A1)) is 0.05 or less, in etching to selectively dissolve silicon relative to silicon germanium.

[19] An etching composition comprising an alkaline compound (A2), an organic reducing agent (excluding a thiol compound (D2)) (B2), and a thiol compound (D2), wherein the mass ratio of the thiol compound (D2) to the alkaline compound (A2) ((D2) / (A2)) is 0.50 or less, and wherein silicon is selectively dissolved relative to silicon germanium.

[20] The etching composition according to

[19] , wherein the organic reducing agent (B2) comprises a reducing sugar.

[21] The etching composition according to

[19] or

[20] , wherein the compound (D2) comprises a thiocarboxylic acid.

[22] The etching composition according to any one of

[19] to

[21] , further comprising water (C2).

[23] The etching composition according to any one of

[19] to

[22] , further comprising a water-miscible solvent.

[24] The etching composition according to any one of

[19] to

[23] , wherein the content of the compound (D2) in 100% by mass of the etching composition is less than 5% by mass (but not including 0).

[25] The etching composition according to

[22] , wherein the content of water (C2) in 100% by mass of the etching composition is 60% by mass or more.

[26] Etching rate ER for silicon at 60°C. Ｓｉ２ and the etching rate ER for silicon germanium ＳｉＧｅ２ The etching composition according to any one of

[19] to

[25] , wherein ER satisfies the following formula (4): Ｓｉ２ / ER ＳｉＧｅ２ ≧35 (4)

[27] The etching composition according to any one of

[19] to

[26] , which is used as an etching composition for dissolving silicon.

[28] The etching composition according to any one of

[19] to

[27] , which dissolves a Si(100) surface after etching at 60°C for 5 minutes, so that the average surface roughness measured on three 1 mm long lines arranged parallel to each other at 0.5 cm intervals on the surface is 120 nm or less.

[29] An etching method for etching a silicon-containing structure using the etching composition according to any one of

[19] to

[28] .

[30] The etching composition according to any one of

[19] to

[28] , which dissolves a silicon-containing structure after etching at 60°C for 5 minutes, so that the average surface roughness measured on three 1 mm long lines arranged parallel to each other at 0.5 cm intervals on the surface is 120 nm or less. ２An etching method comprising the step of etching the silicon surface.

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

[19] to

[28] .

[32] A method for manufacturing a transistor, comprising the step of etching the silicon surface of a silicon-containing structure using the etching composition according to any one of

[19] to

[28] .

[33] The method for manufacturing a transistor according to

[32] , wherein the silicon surface is a surface on the Si layer side in a stack of a SiGe layer and a Si layer.

[34] A method for manufacturing a transistor having a BSPDN structure, comprising the step of etching a silicon-containing structure using the etching composition according to any one of

[19] to

[28] .

[35] An etching method comprising using a composition containing an alkaline compound (A2), an organic reducing agent (excluding a thiol compound (D2)) (B2), and a thiol compound (D2), wherein the mass ratio of the thiol compound (D2) to the alkaline compound (A2) ((D2) / (A2)) is 0.50 or less, in etching to selectively dissolve silicon relative to silicon germanium.

[36] Use of a composition containing an alkaline compound (A2), an organic reducing agent (excluding a thiol compound (D2)) (B2), and a thiol compound (D2), wherein the mass ratio of the thiol compound (D2) to the alkaline compound (A2) ((D2) / (A2)) is 0.50 or less, in etching to selectively dissolve silicon relative to silicon germanium.

[37] An etching composition comprising an alkaline compound (A3) and an organic reducing agent (B3), which dissolves a Si(100) surface after etching at 60°C for 5 minutes so that the average surface roughness measured along three 1 mm long lines arranged parallel to each other at 0.5 cm intervals on the surface is 80 nm or less.

[0012] According to the present invention, it is possible to provide an etching composition having excellent selective solubility of silicon relative to silicon germanium and / or an etching composition having excellent flatness, as well as an etching method using the etching composition, a method for manufacturing a semiconductor device, and a method for manufacturing a transistor.

[0013] 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 an expression "to" is used, it is used as an expression including the numerical values ​​or physical property values ​​before and after it. In the present invention, when describing a quaternary ammonium compound having n carbon atoms, "n" means the total number of carbon atoms in the substituents introduced to the nitrogen atom by covalent bonds. For example, in the case of tetramethylammonium, n = 4, making it a quaternary ammonium compound having 4 carbon atoms.

[0014] The first aspect of the invention is characterized by an etching composition comprising a quaternary ammonium compound (A1) having less than 13 carbon atoms (hereinafter sometimes referred to as "component (A1)"), an organic reducing agent (B1) (hereinafter sometimes referred to as "component (B1)"), and a quaternary ammonium compound (D1) having 13 or more carbon atoms (hereinafter sometimes referred to as "component (D1)"), wherein the mass ratio of the content of compound (D1) to the content of compound (A1) ((D1) / (A1)) is 0.05 or less, and the composition selectively dissolves silicon relative to silicon germanium. The first aspect of the invention is also characterized by an etching method comprising using a composition comprising a quaternary ammonium compound (A1) having less than 13 carbon atoms, an organic reducing agent (B1), and a quaternary ammonium compound (D1) having 13 or more carbon atoms (wherein the mass ratio of the content of compound (D1) to the content of compound (A1) ((D1) / (A1)) is 0.05 or less, for etching to selectively dissolve silicon relative to silicon germanium. Furthermore, the first aspect of the invention is characterized by the use of a composition comprising a quaternary ammonium compound (A1) having less than 13 carbon atoms, an organic reducing agent (B1), and a quaternary ammonium compound (D1) having 13 or more carbon atoms, wherein the mass ratio of the compound (D1) to the compound (A1) ((D1) / (A1)) is 0.05 or less, for etching that selectively dissolves silicon relative to silicon germanium.

[0015] A second aspect of the invention is characterized by an etching composition comprising an alkaline compound (A2) (hereinafter sometimes referred to as "component (A2)"), an organic reducing agent (excluding a thiol compound (D2)) (B2) (hereinafter sometimes referred to as "component (B2)"), and a thiol compound (D2) (hereinafter sometimes referred to as "component (D2)"), wherein the mass ratio of the thiol compound (D2) to the alkaline compound (A2) ((D2) / (A2)) is 0.50 or less, and wherein silicon is selectively dissolved relative to silicon germanium. The second aspect of the invention is also characterized by an etching method comprising using a composition comprising an alkaline compound (A2), an organic reducing agent (excluding a thiol compound (D2)) (B2), and a thiol compound (D2), wherein the mass ratio of the thiol compound (D2) to the alkaline compound (A2) ((D2) / (A2)) is 0.50 or less, for etching to selectively dissolve silicon relative to silicon germanium. Furthermore, a second aspect of the invention is characterized by the use of a composition comprising an alkaline compound (A2), an organic reducing agent (excluding a thiol compound (D2)) (B2), and a thiol compound (D2), wherein the mass ratio of the thiol compound (D2) to the alkaline compound (A2) ((D2) / (A2)) is 0.50 or less, for etching that selectively dissolves silicon relative to silicon germanium.

[0016] In a third aspect of the invention, the etching composition comprises an alkaline compound (A3) (hereinafter, may be referred to as "component (A3)") and an organic reducing agent (B3) (hereinafter, may be referred to as "component (B3)"), and dissolves a Si(100) surface so that the average surface roughness measured along three 1 mm long line segments arranged parallel to each other at 0.5 cm intervals on the surface is 80 nm or less.

[0017] The etching composition of the third aspect of the invention dissolves the Si(100) surface after etching at 60°C for 5 minutes so that the average surface roughness, measured along three 1 mm long lines arranged parallel to each other at 0.5 cm intervals on the surface, is preferably 50 nm or less, more preferably 30 nm or less, even more preferably 20 nm or less, still more preferably 15 nm or less, and particularly preferably 10 nm or less.

[0018] In a fourth aspect of the invention, the etching composition comprises an alkaline compound (A4) (hereinafter sometimes referred to as "component (A4)") and an inorganic reducing agent (B4) (hereinafter sometimes referred to as "component (B4)"), and is characterized by selectively dissolving silicon relative to silicon germanium. The first to fourth aspects are described in detail below.

[0019] [First Aspect] (Component (A1)) The component (A1) is a quaternary ammonium compound having less than 13 carbon atoms. When the etching composition of the present invention contains the quaternary ammonium compound (A1) having less than 13 carbon atoms, the etching composition has excellent silicon solubility.

[0020] Component (A1) can be any quaternary ammonium compound having less than 13 carbon atoms without any particular limitation, and examples of quaternary ammonium compounds having less than 13 carbon atoms include quaternary ammonium salts such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, ethyltrimethylammonium hydroxide, tetrapropylammonium hydroxide, and tetramethylammonium fluoride. These components (A1) may be used alone or in combination of two or more. Among these components (A1), quaternary ammonium hydroxide compounds are preferred because they have a low content of sodium, which tends to affect transistor performance, and an excellent etching rate, and tetramethylammonium hydroxide, tetraethylammonium hydroxide, and ethyltrimethylammonium hydroxide are more preferred.

[0021] 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 composition, because of its excellent silicon solubility. The content of component (A1) is preferably less than 40 mass%, more preferably less than 35 mass%, and even more preferably less than 30 mass%, based on 100 mass% of the etching composition, because of its excellent water solubility. The upper and lower limits can be used in combination without any particular restrictions, and examples include a combination of 0.1 mass% or more and less than 40 mass%.

[0022] (Component (B1)) The component (B1) is an organic reducing agent. When the etching composition of the present invention contains the organic reducing agent (B1), oxidation of germanium is suppressed, thereby suppressing the dissolution reaction of silicon germanium.

[0023] Examples of the component (B1) include reducing sugars, ascorbic acid, aliphatic aldehydes, and aromatic aldehydes. These components (B1) may be used alone or in combination of two or more. Among these components (B1), reducing sugars and ascorbic acid are preferred because of their excellent solubility, and reducing sugars are particularly preferred. Examples of reducing sugars include monosaccharides such as glucose and fructose, and disaccharides such as lactose and maltose.

[0024] The content of component (B1) 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, because it provides excellent protection for silicon germanium. The content of component (B1) is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 15% by mass or less, based on 100% by mass of the etching composition, because it provides excellent silicon solubility. The upper and lower limits of the content of component (B1) are not particularly limited, and components can be used in combination. For example, the content of component (B1) is preferably 0.01% by mass to 50% by mass, more preferably 0.1% by mass to 30% by mass, and even more preferably 1% by mass to 15% by mass, based on 100% by mass of the etching composition.

[0025] (Component (D1)) Component (D1) is a quaternary ammonium compound having 13 or more carbon atoms. When the etching composition of the present invention contains the quaternary ammonium compound (D1) having 13 or more carbon atoms, an etching composition can be obtained that is excellent in the selective solubility of silicon relative to silicon germanium and in the flatness of the Si (100) surface after etching.

[0026] Component (D1) can be any quaternary ammonium compound having 13 or more carbon atoms, and is not particularly limited thereto. However, the substituent constituting the ammonium salt is preferably an organic group having 1 to 20 carbon atoms, more preferably 2 to 8 carbon atoms, and particularly preferably 3 to 5 carbon atoms. Examples of quaternary ammonium compounds having 13 or more carbon atoms include quaternary ammonium hydroxide compounds such as tetrabutylammonium hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide, and hexadecyltrimethylammonium hydroxide, and quaternary ammonium halide compounds such as tetrabutylammonium bromide, decyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, tetrapentylammonium chloride, and tetrahexylammonium chloride. These component (D1) compounds may be used alone or in combination of two or more. Among these components (D1), it is preferable to include a quaternary ammonium compound in which all the alkyl groups are the same, such as tetrabutylammonium hydroxide or tetrabutylammonium bromide, because this makes it easier to obtain an etching composition that is excellent in the selective solubility of silicon relative to silicon germanium and in planarity.

[0027] The content of component (D1) is preferably less than 1 mass% of 100 mass% of the etching composition, more preferably 0.1 mass% or less, even more preferably less than 0.1 mass%, particularly preferably 0.05 mass% or less, because an etching composition having excellent selective solubility of silicon relative to silicon germanium and flatness is easily obtained. The content of component (D1) is preferably more than 0 mass% of 100 mass% of the etching composition, i.e., a value not including 0, because an etching composition having excellent selective solubility of silicon relative to silicon germanium and flatness is easily obtained. The upper and lower limits of the content of component (D1) are not particularly limited, and they can be used in combination.

[0028] (Ratio of mass of component (D1) to component (A1)) The ratio of mass of component (D1) to component (A1) ((D1) / (A1)) is preferably 0.05 or less, more preferably 0.02 or less, even more preferably 0.01 or less, and particularly preferably 0.005 or less, because an etching composition having excellent selective solubility of silicon relative to silicon germanium can be obtained. The lower limit of the ratio of mass of component (D1) to component (A1) ((D1) / (A1)) is not particularly limited as long as it is a value exceeding 0, but is preferably 0.00001 or more, more preferably 0.0001 or more. The upper and lower limits can be used in combination without any particular restrictions.

[0029] (Water: Component (C1)) The etching composition of the first embodiment preferably contains water (hereinafter referred to as "component (C1)") in addition to the component (A1) and the component (B1).

[0030] The content of component (C1) 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 composition, because the etching composition is easy to produce and the solubility of component (A1) and component (B1) is excellent. The content of component (C1) 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 composition, because the solubility of silicon is excellent. The lower limit and upper limit of the content of component (C1) can be used in any combination.

[0031] (Other Components) The etching composition of the first aspect may contain other components in addition to the components (A1) to (D1), as long as the effects of the present invention are not impaired. Examples of other components include a water-miscible solvent, a chelating agent, a surfactant, etc.

[0032] <Water-miscible solvent> When the etching composition of the first aspect contains a water-miscible solvent, it exhibits the effect of making a hydrophobic substance that is not miscible with water miscible with water.

[0033] The water-miscible solvent 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, more preferably 9.0 or more.

[0034] 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.

[0035] In the etching composition of the first aspect, the content of the water-miscible solvent is preferably 5% by mass or less, more preferably 1% by mass or less, and even more preferably less than 0.5% by mass, relative to 100% by mass of the etching composition. In order to achieve excellent solubility of the component (A1), the component (B1), and the component (D1), it is most preferable that the etching composition does not contain a water-miscible solvent (0% by mass).

[0036] <Chelating Agent> When the etching composition of the first aspect contains a chelating agent, the effect of protecting silicon germanium is exerted.

[0037] Examples of chelating agents include amino acids and organic acids. These chelating agents may be used alone or in combination of two or more. Among these chelating agents, amino acids and organic acids are preferred, and amino acids are more preferred, because they have excellent chelating effects.

[0038] 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, (2-dihydroxyethyl)glycine is more preferred because of its excellent chelating effect.

[0039] 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, citric acid and 2-phosphonobutane-1,2,4-tricarboxylic acid are more preferred because of their excellent chelating effect.

[0040] When the etching composition of the first aspect contains a chelating agent, the content of the chelating agent is preferably 0.001 mass% or more, more preferably 0.005 mass% or more, and even more preferably 0.01 mass% or more, relative to 100 mass% of the etching composition, because the chelating effect is excellent. When the etching composition of the present invention contains a chelating agent, the content of the chelating agent is preferably 25 mass% or less, more preferably 10 mass% or less, and even more preferably 6 mass% or less, relative to 100 mass% of the etching composition, because the solubility in water is excellent. The lower and upper limits of the chelating agent can be used in any combination.

[0041] <Surfactant> When the etching composition of the first aspect contains a surfactant, the surface tension of the etching composition decreases, the wettability of the etching composition to the substrate to be etched improves, and the uniformity of etching tends to improve.

[0042] Since the etching composition of the first aspect is usually alkaline, the surfactant used in the etching composition of the present invention can be used without any particular limitation as long as it can be used under alkaline conditions, for example, conditions of a pH of 8 or higher. Examples of usable surfactants include polyethylene glycol and polypropylene glycol.

[0043] The amount of surfactant added to the etching composition of the first aspect is preferably 0.0001% by mass or more in order to obtain a sufficient effect of the surfactant, and the upper limit of the amount of surfactant added is preferably 1% by mass or less in terms of preventing contamination of the substrate after etching and economic efficiency.

[0044] (Mass Ratio of Each Component) The mass ratio of the component (B1) to the component (A1) in the etching composition of the first aspect (mass of component (B1) / mass of component (A1), hereinafter referred to as "(B1) / (A1)") is preferably 0.001 to 2, more preferably 0.005 to 1.5, and even more preferably 0.01 to 1.0, because this provides excellent protection of silicon germanium.

[0045] The mass ratio of the component (D1) to the component (B1) in the etching composition of the first aspect (mass of the component (D1) / mass of the component (B1), hereinafter referred to as "(D1) / (B1)") is preferably 0.001 to 2, as this provides excellent protection of silicon germanium.

[0046] When the etching composition of the first aspect contains the component (C1), the mass ratio of the component (A1) to the component (C1) (mass of the component (A1) / mass of the component (C1), hereinafter referred to as "(A1) / (C1)") 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.

[0047] When the etching composition of the first aspect contains the component (C1), the mass ratio of the component (B1) to the component (C1) (mass of the component (B1) / mass of the component (C1), hereinafter referred to as "(B1) / (C1)") is preferably 0.001 to 0.7, more preferably 0.003 to 0.6, and even more preferably 0.005 to 0.5, because this provides excellent protection of silicon germanium.

[0048] (Method for producing etching composition) The method for producing the etching composition of the first embodiment is not particularly limited, and the etching composition can be produced by mixing component (A1), component (B1), component (D1), and, if necessary, component (C1), 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.

[0049] (Physical Properties of Etching Composition) The pH of the etching composition of the first embodiment is preferably 8 to 14, more preferably 9 to 14, and even more preferably 10 to 14, because this provides excellent silicon solubility.

[0050] The etching composition of the first embodiment is preferably one that selectively dissolves silicon relative to silicon germanium. The etching rate of the first etching composition at 60° C. for single crystal silicon is calculated by ER Ｓｉ１ , etch rate ER in silicon germanium ＳｉＧｅ１In this case, since the etching composition of the first aspect has excellent selective solubility of silicon relative to silicon germanium, the dissolution selectivity ratio (ER) of silicon to silicon germanium is Ｓｉ１ / ER ＳｉＧｅ１ ) preferably satisfies the following formula (1): Ｓｉ１ / ER ＳｉＧｅ１ ≧35 (1) The dissolution selectivity is more preferably 60 or more, and further preferably 100 or more. The silicon etch rate can be controlled, for example, by the pH of the etching composition. Etch Rate ER Ｓｉ１ , etch rate ER ＳｉＧｅ１ The dissolution selectivity ratio is measured and calculated by the method described in the Examples below.

[0051] The etching composition of the first aspect has excellent selective solubility of silicon in silicon germanium, and therefore preferably satisfies the following formula (2): ER Ｓｉ１ (2) The silicon etch rate ER is ≧50 (nm / min) Ｓｉ is more preferably 80 nm / min or more, and even more preferably 100 nm / min or more.

[0052] The silicon germanium etch rate ER of the etching composition of the first embodiment ＳｉＧｅ１ Since the ER has excellent selective solubility of silicon in silicon germanium, it is preferable that the ER satisfies the following formula (3): ＳｉＧｅ１ (3) The etching rate ER of the silicon germanium is ≦3 (nm / min) ＳｉＧｅ１ is more preferably 1.5 nm / min or less, and even more preferably 1 nm / min or less.

[0053] The etching composition of the first aspect has excellent selective solubility of silicon relative to silicon germanium. The etching composition of the first aspect dissolves the Si(100) surface after etching at 60° C. for 5 minutes so that the average surface roughness measured along three 1 mm long lines spaced 0.5 cm apart on the surface is preferably 80 nm or less, more preferably 50 nm or less, even more preferably 30 nm or less, even more preferably 20 nm or less, particularly preferably 15 nm or less, and most preferably 10 nm or less.

[0054] [Second Aspect] The component (A2) is an alkaline compound. By including the alkaline compound (A2), the etching composition of the present invention exhibits excellent silicon solubility. However, the components included in the components (B2) and (D2) described below are not included in the component (A2) of the second aspect.

[0055] Examples of component (A2) include organic alkali compounds such as quaternary ammonium salts such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, ethyltrimethylammonium hydroxide, tetrabutylammonium hydroxide, and tetramethylammonium fluoride; amine compounds such as ethanolamine, trimethyleneamine, 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; and inorganic alkali compounds such as metal hydroxides such as sodium hydroxide, potassium hydroxide, and calcium hydroxide. These component (A2) may be used alone or in combination of two or more. Among these components (A2), it is preferable to include at least one compound selected from the group consisting of quaternary ammonium salts, amine compounds, and metal hydroxides, because these compounds have an excellent etching rate. Quaternary ammonium hydroxide compounds are more preferable, and tetramethylammonium hydroxide, tetraethylammonium hydroxide, and ethyltrimethylammonium hydroxide are even more preferable.

[0056] The content of component (A2) 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 composition, because of its excellent silicon solubility. The content of component (A2) is preferably less than 40 mass%, more preferably less than 35 mass%, and even more preferably less than 30 mass%, based on 100 mass% of the etching composition, because of its excellent water solubility. The upper and lower limits can be used in combination without any particular restrictions, and examples include a combination of 0.1 mass% or more and less than 40 mass%.

[0057] (Component (B2)) Component (B2) is an organic reducing agent. However, in the second aspect of the invention, component (B2) does not include thiol compounds even if they have reducing properties. When the etching composition of the present invention contains component (B2), oxidation of germanium is suppressed, thereby suppressing the dissolution reaction of silicon germanium.

[0058] Examples of component (B2) include reducing sugars, ascorbic acid, aliphatic aldehydes, and aromatic aldehydes. These components (B2) may be used alone or in combination of two or more. Among these components (B2), reducing sugars and ascorbic acid are preferred because of their excellent solubility, and reducing sugars are particularly preferred. Examples of reducing sugars include monosaccharides such as glucose and fructose, and disaccharides such as lactose and maltose.

[0059] The content of component (B2) 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, relative to 100% by mass of the etching composition, because it provides excellent protection for silicon germanium. The content of component (B2) is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 15% by mass or less, relative to 100% by mass of the etching composition, because it provides excellent silicon solubility. The upper and lower limits can be used in combination without any particular restrictions, and examples of such combinations include 0.01% by mass to 50% by mass, 0.1% by mass to 30% by mass, and 1% by mass to 15% by mass.

[0060] (Component (D2)) The etching composition of the second embodiment contains a thiol compound (D2) (component (D2)). The inclusion of component (D2) promotes silicon etching and, in certain cases, further improves the flatness of the Si(100) surface after etching. The thiol compound (D2) of the second embodiment is an organic compound having a sulfanyl group at its terminal. Examples of component (D2) include thiocarboxylic acids such as thioglycolic acid, 8-mercaptooctanoic acid, and 11-mercaptoundecanoic acid, and mercaptoalcohols such as 3-mercapto-1-propanol and 8-mercapto-1-octanol. As component (D2), thiocarboxylic acids and 3-mercapto-1-propanol are preferred, and thiocarboxylic acids are more preferred.

[0061] The lower limit of the content of component (D2) is not particularly limited, but since an etching composition excellent in the selective solubility of silicon relative to silicon germanium can be obtained, it is sufficient that the content is more than 0 mass% relative to 100 mass% of the etching composition, i.e., does not include 0. The content of component (D2) is preferably less than 5 mass% and more preferably less than 1 mass% relative to 100 mass% of the etching composition, since an etching composition excellent in the flatness of the silicon surface can be easily obtained.

[0062] In the etching composition of the second embodiment, the content mass ratio ((D2) / (A2)) of the thiol compound (D2) to the alkaline compound (A2) is 0.5 or less. By satisfying that (D2) / (A2) is 0.50 or less, an etching composition excellent in the selective solubility of silicon relative to silicon germanium can be obtained. Furthermore, from the viewpoint of flatness, (D2) / (A2) is more preferably 0.20 or less, even more preferably 0.10 or less, and particularly preferably 0.02 or less. There is no particular lower limit, but since the composition contains component D2, it is sufficient that it is greater than 0, preferably 0.00001 or more, and more preferably 0.0001 or more. The upper and lower limits can be used in combination without any particular restrictions.

[0063] (Water: Component (C2)) The etching composition of the second embodiment preferably contains water (component (C2)).

[0064] The content of component (C2) 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 composition, because the etching composition is easy to produce and the solubility of components (A2), (B2), and (D2) is excellent. The content of component (C2) 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 composition, because the solubility of silicon is excellent. The upper and lower limits can be used in combination without any particular restrictions.

[0065] (Other Components) The etching composition of the second aspect may contain other components, such as a water-miscible solvent, a chelating agent, a surfactant, etc., as long as the effects of the present invention are not impaired.

[0066] <Water-miscible solvent> When the etching composition of the second aspect contains a water-miscible solvent, it exhibits the effect of making a hydrophobic substance that is not miscible with water miscible with water.

[0067] As the water-miscible solvent, those described in the etching composition of the first embodiment can be used, and one of them may be used alone, or two or more of them may be used in combination.

[0068] In the etching composition of the second aspect, the content of the water-miscible solvent is preferably less than 0.5 mass% relative to 100 mass% of the etching composition, and since the solubility of component (A2) and component (B2) is excellent, it is also preferable that the etching composition does not contain a water-miscible solvent, i.e., is 0 mass%.

[0069] <Chelating Agent> When the etching composition of the second embodiment contains a chelating agent, the effect of protecting silicon germanium is exerted.

[0070] As the chelating agent for the etching composition of the second aspect, those described in the first aspect can be used, and one of them may be used alone, or two or more of them may be used in combination.

[0071] When the etching composition of the second aspect contains a chelating agent, the content of the chelating agent is preferably 0.001 mass% or more, more preferably 0.005 mass% or more, and even more preferably 0.01 mass% or more, based on 100 mass% of the etching composition, because the chelating effect is excellent. When the etching composition of the present invention contains a chelating agent, the content of the chelating agent is preferably 25 mass% or less, more preferably 10 mass% or less, and even more preferably 6 mass% or less, based on 100 mass% of the etching composition, because the solubility in water is excellent. The above lower and upper limits of the chelating agent can be used in any combination.

[0072] (Mass Ratio of Each Component) The mass ratio of the component (B2) to the mass of the component (A2) in the etching composition of the second aspect (mass of component (B2) / mass of component (A2), hereinafter referred to as "(B2) / (A2)") is preferably 0.001 to 2, more preferably 0.005 to 1.5, and even more preferably 0.01 to 1.0, because this provides excellent protection of silicon germanium.

[0073] When the etching composition of the second aspect contains component (C2), the mass ratio of component (A2) to the mass of component (C2) (mass of component (A2) / mass of component (C2), hereinafter referred to as "(A2) / (C2)") 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.

[0074] When the etching composition of the second aspect contains component (C2), the mass ratio of component (B2) to the mass of component (C2) (mass of component (B2) / mass of component (C2), hereinafter referred to as "(B2) / (C2)") is preferably 0.001 to 0.7, more preferably 0.003 to 0.6, and even more preferably 0.005 to 0.5, because this provides excellent protection of silicon germanium.

[0075] The mass ratio of the component (D2) to the mass of the component (B2) in the etching composition of the second aspect (mass of the component (D2) / mass of the component (B2), hereinafter referred to as "(D2) / (B2)") is preferably 0.0001 to 2, since this results in excellent silicon flatness.

[0076] (Method for producing etching composition) The method for producing the etching composition of the second aspect is not particularly limited, and the etching composition can be produced by mixing component (A2), component (B2), component (D2), and, if necessary, component (C2), and other components.

[0077] (Physical Properties of Etching Composition) The pH of the etching composition of the second embodiment is preferably 8 to 14, more preferably 9 to 14, and even more preferably 10 to 14, because this provides excellent silicon solubility.

[0078] The etching composition of the second embodiment is preferably one that selectively dissolves silicon relative to silicon germanium. The etching rate of the second etching composition at 60° C. for single crystal silicon is calculated by ER Ｓｉ２ , etch rate ER in silicon germanium ＳｉＧｅ２ In this case, since the etching composition of the second embodiment has excellent selective solubility of silicon relative to silicon germanium, the dissolution selectivity ratio (ER) of silicon to silicon germanium is Ｓｉ２ / ER ＳｉＧｅ２ ) preferably satisfies the following formula (4): Ｓｉ２ / ER ＳｉＧｅ２ ≧35 (4) The dissolution selectivity is more preferably 60 or more, further preferably 100 or more, and particularly preferably 250 or more. The silicon etch rate can be controlled, for example, by the pH of the etching composition. Etch Rate ER Ｓｉ２ , etch rate ER ＳｉＧｅ２ The dissolution selectivity ratio is measured and calculated by the method described in the Examples below.

[0079] The etching composition of the second aspect has excellent selective solubility of silicon in silicon germanium, and therefore preferably satisfies the following formula (5): ER Ｓｉ２ (5) The silicon etch rate ER is ≧50 (nm / min) Ｓｉ２ is more preferably 80 nm / min or more, and even more preferably 100 nm / min or more.

[0080] The silicon germanium etch rate ER of the etching composition of the second embodiment ＳｉＧｅ２ Since the selective solubility of silicon in silicon germanium is excellent, it is preferable that ER satisfies the following formula (6): ＳｉＧｅ２ (6) The etching rate ER of the silicon germanium is ≦3 (nm / min) ＳｉＧｅ２ is more preferably 1.5 nm / min or less, and even more preferably 1 nm / min or less.

[0081] The etching composition of the second aspect has excellent selective solubility of silicon relative to silicon germanium. The etching composition of the second aspect dissolves the Si(100) surface after etching at 60° C. for 5 minutes so that the average surface roughness measured along three 1 mm long lines spaced 0.5 cm apart on the surface is preferably 120 nm or less, more preferably 80 nm or less, even more preferably 50 nm or less, even more preferably 30 nm or less, particularly preferably 20 nm or less, particularly more preferably 15 nm or less, and most preferably 10 nm or less.

[0082] [Third Aspect] (Component (A3)) The component (A3) is an alkaline compound. When the etching composition of the present invention contains the alkaline compound (A3), it has excellent silicon solubility. However, components (B3) and (D3) described below are not included in the alkaline compound.

[0083] Examples of component (A3) include organic alkali compounds such as quaternary ammonium hydroxide compounds such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, ethyltrimethylammonium hydroxide, and tetrabutylammonium hydroxide; amine compounds such as ethanolamine, trimethyleneamine, 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; and inorganic alkali compounds such as metal hydroxides such as sodium hydroxide, potassium hydroxide, and calcium hydroxide. These component (A) may be used alone or in combination of two or more. Among these components (A), quaternary ammonium hydroxide compounds, amine compounds, potassium hydroxide, and calcium hydroxide are preferred because they have a low content of sodium, which is likely to affect transistor performance, and quaternary ammonium hydroxide compounds are more preferred, with tetramethylammonium hydroxide, tetraethylammonium hydroxide, and ethyltrimethylammonium hydroxide being even more preferred.

[0084] The content of component (A3) 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 composition, because of its excellent solubility in silicon. The content of component (A3) 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 composition, because of its excellent solubility in water.

[0085] (Component (B3)) The component (B3) is an organic reducing agent. When the etching composition of the present invention contains the organic reducing agent (B3), oxidation of germanium is suppressed, thereby suppressing the dissolution reaction of silicon germanium.

[0086] Examples of component (B3) include reducing sugars, ascorbic acid, aliphatic aldehydes, and aromatic aldehydes. These components (B3) may be used alone or in combination of two or more. Among these components (B3), reducing sugars and ascorbic acid are preferred because of their excellent solubility, and reducing sugars are particularly preferred. Examples of reducing sugars include monosaccharides such as glucose and fructose, and disaccharides such as lactose and maltose.

[0087] The content of component (B3) 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 composition, because it provides excellent protection of silicon germanium. The content of component (B3) is preferably 20 mass% or less, more preferably 18 mass% or less, and even more preferably 15 mass% or less, based on 100 mass% of the etching composition, because it provides excellent solubility of silicon.

[0088] (Component (D3)) The etching composition of the third aspect preferably contains, in addition to component (A3), component (B3), and component (C3) as an optional component described later, a quaternary ammonium salt having 8 or more carbon atoms (excluding the same compound as component (A3)) and / or a thiol compound (component (D3)). By containing component (D3), the flatness of the Si (100) surface after etching is excellent. Component (D3) may be a quaternary ammonium salt having 8 or more carbon atoms alone, a thiol compound alone, or a mixture thereof.

[0089] Examples of quaternary ammonium salts having 8 or more carbon atoms are, due to their excellent selective solubility of silicon relative to silicon germanium, preferred are tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide, benzyltrimethylammonium hydroxide, and tetrabutylammonium bromide; more preferred are tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, and tetrabutylammonium bromide; even more preferred are tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and tetrabutylammonium bromide; and most preferred is tetrabutylammonium hydroxide. Quaternary ammonium salts having 8 or more carbon atoms may be used alone or in combination of two or more. Examples of thiol compounds include thioglycolic acid, 8-mercaptooctanoic acid, 11-mercaptoundecanoic acid, 3-mercapto-1-propanol, and 8-mercapto-1-octanol. Thioglycolic acid and 3-mercapto-1-propanol are preferred, and thioglycolic acid is particularly preferred.

[0090] The content of component (D3) is preferably 0.001% by mass or more, more preferably 0.002% by mass or more, and even more preferably 0.005% by mass or more, relative to 100% by mass of the etching composition, because this provides excellent flatness of the silicon surface. The content of component (D3) is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less, relative to 100% by mass of the etching composition, because this provides excellent silicon solubility.

[0091] [Fourth Aspect] (Component (A4)) For the component (A4) in the fourth aspect, the alkaline compound described in the third aspect can be used in the same manner as in the third aspect. For the same reasons as those described in the third aspect, the content of component (A4) is preferably 0.1 mass% or more, more preferably 0.2 mass% or more, and even more preferably 0.5 mass% or more, and is preferably 39.99 mass% or less, more preferably 34.95 mass% or less, and even more preferably 29.92 mass% or less, relative to 100 mass% of the etching composition.

[0092] (Component (B4)) The component (B4) in the fourth embodiment is an inorganic reducing agent. When the etching composition of the present invention contains the inorganic reducing agent (B4), oxidation of germanium is suppressed, thereby suppressing the dissolution reaction of silicon germanium.

[0093] Examples of component (B4) include sulfurous acid, ammonium hydrogen sulfite, phosphinic acid, and phosphonic acid. These components (B4) may be used alone or in combination of two or more. Among these components (B4), sulfurous acid and ammonium hydrogen sulfite are more preferred, and sulfurous acid is particularly preferred, because they are excellent at inhibiting the oxidation of germanium.

[0094] The content of component (B4) 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 composition, because it provides excellent protection for silicon germanium. The content of component (B4) is preferably 20 mass% or less, more preferably 18 mass% or less, and even more preferably 15 mass% or less, relative to 100 mass% of the etching composition, because it provides excellent dissolution of silicon.

[0095] <Components Common to the Third and Fourth Aspects> (Water: Component (C)) When referring to either component (A3) or component (A4) of the etching compositions of the third and fourth aspects, the term "component (A)" is used hereinafter, and when referring to either component (B3) or component (B4), the term "component (B)" is used hereinafter. The etching composition of the third aspect preferably contains water (component (C3)), and the etching composition of the fourth aspect preferably also contains water (component (C4)). When referring to either component (C3) or component (C4), the term "component (C)" is used hereinafter.

[0096] 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 composition, because the etching composition 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 composition, because the solubility of silicon is excellent.

[0097] (Other Components) The etching compositions of the third and fourth aspects may contain other components in addition to the components (A), (B), and (C), as long as the effects of the present invention are not impaired. Examples of other components include a chelating agent, a water-miscible solvent, and a surfactant.

[0098] <Chelating Agent> In both the etching compositions of the third and fourth aspects, the effect of protecting silicon germanium is exhibited by including a chelating agent.

[0099] As the chelating agent for the etching compositions of the third and fourth aspects, those described in the first aspect can be used, and one of them may be used alone, or two or more of them may be used in combination.

[0100] When the etching compositions of the third and fourth aspects contain a chelating agent, the content of the chelating agent is preferably 0.001 mass% or more, more preferably 0.005 mass% or more, and even more preferably 0.01 mass% or more, relative to 100 mass% of the etching composition, because the chelating effect is excellent. When the etching compositions of the third and fourth aspects contain a chelating agent, the content of the chelating agent is preferably 25 mass% or less, more preferably 10 mass% or less, and even more preferably 6 mass% or less, relative to 100 mass% of the etching composition, because the solubility in water is excellent.

[0101] <Water-miscible solvent> In both the etching compositions of the third and fourth aspects, the inclusion of a water-miscible solvent exerts the effect of making a hydrophobic substance that is not miscible with water miscible with water.

[0102] In both the third and fourth aspects, the water-miscible solvents of the etching composition may be those described in the first aspect, and one of them may be used alone, or two or more of them may be used in combination.

[0103] In the etching compositions of either the third aspect or the fourth aspect, the content of the water-miscible solvent is preferably 5% by mass or less, and more preferably 1% by mass or less, relative to 100% by mass of the etching composition. It is most preferable that the etching composition does not contain a water-miscible solvent, as this provides excellent solubility of the component (A) and the component (B).

[0104] (Mass Ratio of Each Component) In both the third and fourth aspects, the mass ratio of component (B) to component (A) in the etching composition (mass of component (B) / mass of component (A), hereinafter referred to as "(B) / (A)") is preferably 0.001 to 2, more preferably 0.005 to 1.5, and even more preferably 0.01 to 1.0, because this provides excellent protection of silicon germanium.

[0105] In both the third and fourth aspects, when the etching composition 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.

[0106] In both the third and fourth aspects, when the etching composition 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 0.001 to 0.7, more preferably 0.003 to 0.6, and even more preferably 0.005 to 0.5, because this provides excellent protection of silicon germanium.

[0107] When the etching composition of the third aspect contains component (D3), the mass ratio of component (D3) to component (A3) (mass of component (D3) / mass of component (A3), hereinafter referred to as "(D3) / (A3)") is preferably 0.0001 to 2, more preferably 0.0005 to 1.5, and even more preferably 0.001 to 1.0, in order to achieve excellent silicon flatness.

[0108] (Method for Producing Etching Composition) The method for producing the etching composition of the third aspect is not particularly limited, and the etching composition can be produced by mixing component (A3), component (B3), and, if necessary, component (C3), component (D3), and other components. The method for producing the etching composition of the fourth aspect is not particularly limited, and the etching composition can be produced by mixing component (A4), component (B4), and, if necessary, component (C4), and other components. In both the third and fourth aspects, 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.

[0109] (Physical Properties of Etching Composition) In both the third and fourth aspects, the pH of the etching composition is preferably 8 to 14, more preferably 9 to 14, and even more preferably 10 to 14, because this provides excellent silicon solubility.

[0110] The etching composition of the third and fourth aspects is preferably one that selectively dissolves silicon relative to silicon germanium. In both the third and fourth aspects, the silicon etch rate ER of the etching composition is Ｓｉ Since the selective solubility of silicon in silicon germanium is excellent, the etching rate ER of silicon is preferably 50 nm / min or more, and more preferably 100 nm / min or more. Ｓｉ means the etch rate for single crystal silicon, and is the value at 60° C. The etch rate for silicon can be controlled, for example, by the pH of the etching composition.

[0111] In both the third and fourth aspects, the etching composition has a silicon germanium etch rate ER ＳｉＧｅ Since the selective solubility of silicon in silicon germanium is excellent, the rate is preferably 10 nm / min or less, more preferably 8 nm / min or less, and even more preferably 5 nm / min or less.

[0112] In both the third and fourth aspects, the etching composition has a dissolution selectivity (ER) between silicon and silicon germanium. Ｓｉ / ER ＳｉＧｅ ) is preferably 35 or more because it provides excellent selective solubility of silicon in silicon germanium. In other words, it is preferable to satisfy the following formula (7): Ｓｉ / ER ＳｉＧｅ ≧35 (7) The dissolution selectivity ratio is more preferably 50 or more, and even more preferably 70 or more.

[0113] Etch Rate ER Ｓｉ , etch rate ER ＳｉＧｅ The dissolution selectivity ratio is measured and calculated by the method described in the Examples below.

[0114] (Subject to be etched by etching composition) In any of the first to fourth aspects, the etching composition has excellent solubility for silicon, and therefore the etching composition is used as an etching composition that dissolves silicon. The etching subject of the etching composition is preferably a silicon-containing structure, particularly a silicon surface of a silicon-containing structure, and a semiconductor device including the structure. The silicon is preferably single crystal silicon.

[0115] In any of the first to fourth aspects, the etching composition suppresses dissolution of silicon germanium, promotes dissolution of silicon, and exhibits excellent selective solubility of silicon relative to silicon germanium. Therefore, structures containing silicon and silicon germanium, and semiconductor devices containing such structures, are suitable targets for etching with the etching composition. The silicon is preferably single-crystal silicon. The structure containing silicon and silicon germanium is preferably a laminate of a silicon germanium layer (SiGe layer) and a silicon layer (Si layer), and a structure containing a Si layer and a SiGe layer used in forming a BSPDN structure is particularly suitable.

[0116] In any of the first to fourth aspects, the silicon content in the silicon germanium to be etched is preferably 10 mass% or more, and more preferably 20 mass% or more, based on 100 mass% of silicon germanium, because this is suitable for etching with an etching composition. In any of the first to fourth aspects, the silicon content in the silicon germanium to be etched is preferably 98 mass% or less, and more preferably 95 mass% or less, based on 100 mass% of silicon germanium, because this is suitable for etching with an etching composition.

[0117] In any of the first to fourth aspects, the germanium content in the silicon germanium to be etched is preferably 2 mass% or more, and more preferably 5 mass% or more, based on 100 mass% of silicon germanium, since this is suitable for etching with an etching composition. In any of the first to fourth aspects, the germanium content in the silicon germanium to be etched is preferably 90 mass% or less, and more preferably 80 mass% or less, based on 100 mass% of silicon germanium, since this is suitable for etching with an etching composition.

[0118] The silicon germanium alloy layer (film) may be formed by a known method, but is preferably formed by a crystal growth method because it provides excellent mobility of electrons and holes after transistor formation.

[0119] In a structure containing silicon and silicon germanium or a structure in which silicon and silicon germanium are stacked, silicon oxide may be exposed.

[0120] (Etching Method) The etching method of the present invention is a method for etching a silicon-containing structure, particularly a silicon surface of a silicon-containing structure, and / or a method for etching a structure containing silicon and silicon germanium, using the etching composition of any one of the first to fourth aspects.

[0121] The etching method can be a known method, such as a batch method or a single wafer method.

[0122] The temperature during etching is preferably 15° C. or higher, more preferably 20° C. or higher, because this can improve the etch rate. The temperature during etching is preferably 100° C. or lower, more preferably 80° C. or lower, from the viewpoints 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.

[0123] <Uses> The etching compositions of the first to fourth aspects and the etching methods of the first to fourth aspects can be suitably used in a method for manufacturing a semiconductor device including a step of etching a silicon-containing structure, a method for manufacturing a transistor including a step of etching a silicon surface of a silicon-containing structure, and a method for manufacturing a transistor having a BSPDN structure including a step of etching a silicon-containing structure. The silicon surface is preferably the surface on the Si layer side of a stack of a SiGe layer and a Si layer.

[0124] The etching compositions of the first and third aspects are excellent in planarity, and the etching composition of the second aspect also includes an etching composition excellent in planarity. Therefore, the etching compositions of the first to third aspects are each used in an etching method for etching a wide range of silicon surfaces to make them smooth. For example, the etching composition can be used to etch a silicon surface having a surface area of ​​1 mm ２ The etching method includes the step of etching the silicon surface. ２ A method for manufacturing a semiconductor device, comprising the steps of etching the silicon surface, and further comprising the steps of: ２ A method for manufacturing a transistor including the above-mentioned step of etching the silicon surface, and further a method for manufacturing a transistor including the above-mentioned step of etching the silicon surface, ２ The method is preferably used in a method for manufacturing a transistor having a BSPDN structure, which includes the step of etching the silicon surface. The silicon surface is preferably the surface on the Si layer side of a stack of a SiGe layer and a Si layer.

[0125] The etching compositions of the first to fourth aspects are excellent in the selective solubility of silicon relative to silicon germanium. Furthermore, the etching compositions of the first and third aspects, and some of the etching compositions of the second aspect, are also excellent in the flatness of the silicon surface after etching. Due to these properties, the etching compositions of the present invention can be suitably used in the production of BSPDN.

[0126] The etching method of the present invention, the method for manufacturing a semiconductor device of the present invention, and the method for manufacturing a transistor which may have a BSPDN structure of the present invention can manufacture desired products with a high yield by performing highly accurate etching in the etching step.

[0127] The present invention also includes the following in a third aspect. [1] An etching composition comprising an alkaline compound (A3) and an organic reducing agent (B3), which dissolves a Si(100) surface after etching at 60°C for 5 minutes, such that the average surface roughness measured along three parallel 1 mm line segments spaced 0.5 cm apart on the surface is 80 nm or less. [2] The etching composition according to [1], which selectively dissolves silicon relative to silicon germanium. [3] The etching composition according to [1] or [2], wherein the alkaline compound (A3) comprises at least one compound selected from the group consisting of a quaternary ammonium hydroxide compound, an amine compound, and a metal hydroxide. [4] The etching composition according to any one of [1] to [3], wherein the alkaline compound (A3) comprises a quaternary ammonium hydroxide compound. [5] The etching composition according to any one of [1] to [4], wherein the organic reducing agent (B3) comprises a reducing sugar. [6] The etching composition according to any one of [1] to [5], further comprising water (C3). [7] The etching composition according to [6], wherein the content of water in 100% by mass of the etching composition is 60% by mass or more. [8] The etching composition according to any one of [1] to [7], further comprising a quaternary ammonium salt having 8 or more carbon atoms (excluding the same compound as component (A3)) and / or a thiol compound (D3). [9] The etching composition according to any one of [1] to [8], wherein the content of the alkaline compound (A3) in 100% by mass of the etching composition is 0.1% by mass to 39.99% by mass.

[10] The etching composition according to any one of [1] to [9], wherein the content of the organic reducing agent (B3) in 100% by mass of the etching composition is 0.01% by mass to 20% by mass.

[11] The etching composition according to [8], wherein the content of the quaternary ammonium salt and / or thiol compound (D3) having 8 or more carbon atoms in 100 mass% of the etching composition is 0.001 mass% to 10 mass%.

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

[11] , wherein the mass of the organic reducing agent (B3) relative to the mass of the alkaline compound (A3) is 0.001 to 2.

[13] The etching composition according to [8], wherein the ratio by mass of the quaternary ammonium salt having 8 or more carbon atoms and / or the thiol compound (D3) to the mass of the alkaline compound (A3) is 0.0001 to 2.

[14] Etching rate ER for silicon. Ｓｉ and the etching rate ER for silicon germanium ＳｉＧｅ The etching composition according to any one of [1] to

[13] , wherein ER satisfies the following formula (7): Ｓｉ / ER ＳｉＧｅ ≧35 (7)

[15] The etching composition according to any one of [1] to

[14] , which is used as an etching composition for dissolving silicon.

[16] The etching composition according to any one of [1] to

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

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

[16] .

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

[16] .

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

[16] .

[20] A method for manufacturing a transistor having a BSPDN structure, comprising a step of etching a silicon-containing structure using the etching composition according to any one of [1] to

[16] .

[0128] The present invention also includes the following as a fourth aspect of the invention. [1] An etching composition comprising an alkaline compound (A4) and an inorganic reducing agent (B4), which selectively dissolves silicon relative to silicon germanium. [2] The etching composition according to [1], wherein the alkaline compound (A4) comprises at least one compound selected from the group consisting of a quaternary ammonium hydroxide compound, an amine compound, and a metal hydroxide. [3] The etching composition according to [1] or [2], wherein the alkaline compound (A4) comprises a quaternary ammonium hydroxide compound. [4] The etching composition according to any one of [1] to [3], wherein the inorganic reducing agent (B4) comprises sulfurous acid. [5] The etching composition according to any one of [1] to [4], further comprising water. [6] The etching composition according to [5], wherein the content of water in 100 mass% of the etching composition is 60 mass% or more. [7] The etching composition according to any one of [1] to [6], wherein the content of the alkaline compound (A4) in 100 mass% of the etching composition is 0.1 mass% to 39.99 mass%. [8] The etching composition according to any one of [1] to [7], wherein the content of the inorganic reducing agent (B4) in 100 mass% of the etching composition is 0.01 mass% to 20 mass%. [9] The etching composition according to any one of [1] to [8], wherein the ratio of the mass of the inorganic reducing agent (B4) to the mass of the alkaline compound (A4) is 0.001 to 2.

[10] The etching rate ER for silicon Ｓｉ and the etching rate ER for silicon germanium ＳｉＧｅ The etching composition according to any one of [1] to [9], wherein ER satisfies the following formula (7): Ｓｉ / ER ＳｉＧｅ≧35 (7)

[11] The etching composition according to any one of [1] to

[10] , which is used as an etching composition for dissolving silicon.

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

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

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

[12] .

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

[12] .

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

[12] .

[16] A method for manufacturing a transistor having a BSPDN structure, comprising the step of etching a silicon-containing structure using the etching composition according to any one of [1] to

[12] .

[0129] 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.

[0130] <Silicon Etch Rate and Surface Flatness> A silicon (100) substrate having a thickness of 0.75 mm and a size of 20 mm x 20 mm was immersed in a 0.5 mass % aqueous solution of hydrofluoric acid for 60 seconds, then rinsed with ultrapure water. After that, half of the substrate was masked and immersed at 60°C in the etching compositions obtained in the Examples and Comparative Examples of Embodiments 1 to 4. The immersion time was 5 minutes for the Examples and 3 minutes for the Comparative Examples. The film thickness with and without masking was measured using a contact step gauge, and the silicon etch rate ER was calculated using the following equation (8): Ｓｉ [nm / min] was calculated. Ｓｉ [nm / min] = (silicon film thickness with masking - silicon film thickness without masking) ÷ immersion time (8) When measuring surface flatness, the silicon surface roughness after immersion was measured using a contact profilometer. The surface flatness was expressed as the average surface roughness (nm) measured along three 1 mm long lines arranged parallel to each other at 0.5 cm intervals in the center of the silicon (100) surface.

[0131] <Silicon Germanium Etch Rate> A substrate on which a 50 nm thick silicon germanium layer was laminated was immersed in a 0.5 mass % aqueous solution of hydrofluoric acid for 60 seconds, then rinsed with ultrapure water, and then immersed at 60°C in the etching compositions obtained in the Examples and Comparative Examples of Embodiments 1 to 4. The immersion time was 5 minutes in the Examples and 3 minutes in the Comparative Examples. The film thickness before and after immersion was measured with an ellipsometer, and the etch rate ER of the silicon germanium layer was calculated using the following equation (9): ＳｉＧｅ [nm / min] was calculated. ＳｉＧｅ [nm / min] = (silicon germanium film thickness before immersion - silicon germanium film thickness after immersion) ÷ immersion time (9)

[0132] <Dissolution Selectivity Ratio of Silicon and Silicon Germanium> The dissolution selectivity ratio of silicon germanium and silicon was calculated using the following formula (10): Dissolution Selectivity Ratio = ER Ｓｉ [nm / min]÷ER ＳｉＧｅ [nm / min] (10)

[0133] [First Aspect] (Raw Materials) The following were used as raw materials for producing the etching compositions in the Examples and Comparative Examples: Component (A1-1): tetramethylammonium hydroxide Component (B1-1): glucose Component (D1-1): tetrabutylammonium hydroxide Component (D1-2): tetrabutylammonium bromide

[0134] [Example 1-1] The etching composition was mixed so that, based on 100 mass%, the components were 9.12 mass% of component (A1-1), 5.0 mass% of component (B1-1), 0.01 mass% of component (D1-1), and the remainder was water, and the mixture was bubbled with nitrogen gas for 5 minutes to obtain an etching composition. The evaluation results of the obtained etching composition are shown in Table 1.

[0135] [Examples 1-2 to 1-3] Etching compositions were obtained in the same manner as in Example 1-1, except that the types and contents of the components of the etching compositions were changed as shown in Table 1. The evaluation results of the obtained etching compositions are shown in Table 1.

[0136] Etching compositions were obtained in the same manner as in Example 1-1, except that the types and contents of the components of the etching compositions were changed as shown in Table 1. The evaluation results of the obtained etching compositions are shown in Table 1.

[0137]

[0138] As can be seen from Table 1, the etching compositions obtained in the examples of the first aspect are excellent in selective solubility of silicon relative to silicon germanium and in planarity. Therefore, the etching compositions of the first aspect are considered suitable as etching compositions to be used for forming a BSPDN structure. On the other hand, the etching compositions obtained in the comparative examples were inferior in selective solubility of silicon relative to silicon germanium and in planarity. Therefore, they are considered unsuitable for forming a BSPDN structure.

[0139] [Second Aspect] (Raw Materials) The following were used as raw materials for producing the etching compositions in the Examples and Comparative Examples: Component (A2-1): tetramethylammonium hydroxide Component (B2-1): glucose Component (D2-1): thioglycolic acid

[0140] [Example 2-1] The etching composition was mixed so that, based on 100 mass%, the components were 9.12 mass% of component (A2-1), 5.0 mass% of component (B2-1), 0.01 mass% of component (D2-1), and the remainder was water, and the components were bubbled with nitrogen gas for 5 minutes to obtain an etching composition. The evaluation results of the obtained etching composition are shown in Table 2.

[0141] Examples 2-2 to 2-4 Etching compositions were obtained in the same manner as in Example 2-1, except that the types and contents of the components of the etching compositions were changed as shown in Table 2. The evaluation results of the obtained etching compositions are shown in Table 2.

[0142] Etching compositions were obtained in the same manner as in Example 2-1, except that the types and contents of the components of the etching compositions were changed as shown in Table 2. The evaluation results of the obtained etching compositions are shown in Table 2.

[0143]

[0144] As can be seen from Table 2, the etching compositions obtained in the examples are remarkably excellent in the selective solubility of silicon relative to silicon germanium. Furthermore, Examples 2-1 to 2-3, which have a smaller content ratio (D2 / A2) than Example 2-4, also have excellent flatness. Therefore, the etching composition in the second aspect is considered to be suitable as an etching composition used for forming a BSPDN structure. On the other hand, the etching compositions obtained in the comparative examples were inferior in the selective solubility of silicon relative to silicon germanium and had poor flatness. Therefore, they are considered to be unsuitable for forming a BSPDN structure.

[0145] [Third Aspect] (Raw Materials) The following were used as raw materials for producing the etching compositions in the Examples and Comparative Examples: Component (A3-1): Tetramethylammonium hydroxide Component (B3-1): Glucose Component (C3): Water Component (D3-1): Tetrabutylammonium hydroxide Component (D3-2): Tetrabutylammonium bromide Component (D3-3): Thioglycolic acid

[0146] [Example 3-1] The etching composition was mixed so that, based on 100 mass%, the components were 9.12 mass% of component (A3-1), 5.0 mass% of component (B3-1), 0.01 mass% of component (D3-1), and the remainder was water, and the components were bubbled with nitrogen gas for 5 minutes to obtain an etching composition. The evaluation results of the obtained etching composition are shown in Table 3.

[0147] [Examples 3-2 to 3-5] Etching compositions were obtained in the same manner as in Example 3-1, except that the types and contents of the components of the etching compositions were changed as shown in Table 3. The evaluation results of the obtained etching compositions are shown in Table 3.

[0148] Etching compositions were obtained in the same manner as in Example 3-1, except that the types and contents of the components of the etching compositions were changed as shown in Table 3. The evaluation results of the obtained etching compositions are shown in Table 3.

[0149]

[0150] As can be seen from Table 3, the etching compositions obtained in the examples of the third aspect were excellent in the flatness of the silicon (100) surface after etching. Furthermore, the etching compositions obtained in the examples were remarkably excellent in the selective solubility of silicon relative to silicon germanium. Therefore, they are considered to be suitable as etching compositions for use in forming a BSPDN structure. On the other hand, the etching composition obtained in Comparative Example 3-1 did not contain component (B) and exhibited poor selective solubility of silicon relative to silicon germanium. The etching compositions obtained in Comparative Examples 3-2 and 3-3 were poor in the flatness of the silicon (100) surface after etching, and are therefore considered to be unsuitable for forming a BSPDN structure.

[0151] [Fourth Aspect] (Raw Materials) The following were used as raw materials for producing the etching compositions in the Examples and Comparative Examples: Component (A4-1): tetramethylammonium hydroxide Component (B4-1): sulfurous acid

[0152] [Example 4-1] An etching composition was obtained by mixing the components so that, based on 100 mass% of the etching composition, the component (A4-1) was 4.10 mass%, the component (B4-1) was 0.82 mass%, and water was the remainder. The evaluation results of the obtained etching composition are shown in Table 1.

[0153] [Examples 4-2 and 4-3] Etching compositions were obtained in the same manner as in Example 4-1, except that the types and contents of the components of the etching compositions were changed as shown in Table 4. The evaluation results of the obtained etching compositions are shown in Table 4.

[0154] [Comparative Examples 4-1 and 4-2] Etching compositions were obtained in the same manner as in Example 4-1, except that the types and contents of the components of the etching compositions were changed as shown in Table 4. The evaluation results of the obtained etching compositions are shown in Table 4.

[0155]

[0156] As can be seen from Table 4, the etching compositions obtained in the examples of the fourth aspect have excellent selective solubility of silicon relative to silicon germanium. Therefore, they are considered to be suitable as etching compositions to be used for forming a BSPDN structure. On the other hand, the etching compositions obtained in the comparative examples have poor selective solubility of silicon relative to silicon germanium. Therefore, they are considered to be unsuitable for forming a BSPDN structure.

[0157] The etching compositions of the first to fourth aspects are excellent in the selective solubility of silicon relative to silicon germanium. Furthermore, the etching compositions of the first and third aspects, as well as some of the second aspect, are excellent in the flatness of the silicon (100) surface after etching. Therefore, the etching compositions of the first to fourth aspects are particularly suitable as etching compositions used for producing a BSPDN structure.

Claims

1. An etching composition comprising a quaternary ammonium compound (A1) having less than 13 carbon atoms, an organic reducing agent (B1), and a quaternary ammonium compound (D1) having 13 or more carbon atoms, wherein the mass ratio of the compound (D1) to the compound (A1) ((D1) / (A1)) is 0.05 or less, and wherein silicon is selectively dissolved relative to silicon germanium.

2. The etching composition of claim 1, wherein the organic reducing agent (B1) comprises a reducing sugar.

3. The etching composition according to claim 1, wherein the compound (D1) comprises a quaternary ammonium compound in which all of the alkyl groups are the same.

4. The etching composition according to claim 1, further comprising water (C1).

5. The etching composition of claim 1 further comprising a water-miscible solvent.

6. The etching composition according to claim 1, wherein the content of the compound (D1) in 100% by mass of the etching composition is less than 1% by mass (but does not include 0).

7. The etching composition according to claim 4, wherein the content of water (C1) in 100% by mass of the etching composition is 60% by mass or more.

8. Etching rate ER for silicon at 60°C Ｓｉ１ and the etching rate ER for silicon germanium ＳｉＧｅ１ The etching composition according to claim 1, wherein ER satisfies the following formula (1): Ｓｉ１ / ER ＳｉＧｅ１ ≧35 (1) 9. The etching composition according to claim 1, which is used as an etching composition for dissolving silicon.

10. The etching composition according to claim 1, which dissolves a Si (100) surface after etching at 60°C for 5 minutes so that the average surface roughness measured along three 1 mm long lines placed parallel to each other at 0.5 cm intervals on the surface is 80 nm or less.

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

12. Using the etching composition according to any one of claims 1 to 10, ２ An etching method comprising the above step of etching the silicon surface.

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

14. A method for manufacturing a transistor, comprising the step of etching a silicon surface of a silicon-containing structure using the etching composition according to any one of claims 1 to 10.

15. The method for manufacturing a transistor according to claim 14, wherein the silicon surface is a surface on the Si layer side in a stack of a SiGe layer and a Si layer.

16. A method for manufacturing a transistor having a BSPDN structure, comprising the step of etching a silicon-containing structure using the etching composition according to any one of claims 1 to 10.

17. An etching method comprising using a composition containing a quaternary ammonium compound (A1) having less than 13 carbon atoms, an organic reducing agent (B1), and a quaternary ammonium compound (D1) having 13 or more carbon atoms, wherein the mass ratio of compound (D1) to compound (A1) ((D1) / (A1)) is 0.05 or less, for etching to selectively dissolve silicon relative to silicon germanium.

18. Use of a composition comprising a quaternary ammonium compound (A1) having less than 13 carbon atoms, an organic reducing agent (B1), and a quaternary ammonium compound (D1) having 13 or more carbon atoms, wherein the mass ratio of compound (D1) to compound (A1) ((D1) / (A1)) is 0.05 or less, in etching that selectively dissolves silicon relative to silicon germanium.

19. An etching composition comprising an alkaline compound (A2), an organic reducing agent (excluding a thiol compound (D2)) (B2), and a thiol compound (D2), wherein the mass ratio of the thiol compound (D2) to the alkaline compound (A2) ((D2) / (A2)) is 0.5 or less, and which selectively dissolves silicon relative to silicon germanium.

20. The etching composition of claim 19, wherein the organic reducing agent (B2) comprises a reducing sugar.

21. The etching composition of claim 19, wherein the compound (D2) comprises a thiocarboxylic acid.

22. The etching composition of claim 19, further comprising water (C).

23. The etching composition of claim 19, further comprising a water-miscible solvent.

24. The etching composition according to claim 19, wherein the content of the compound (D2) in 100% by mass of the etching composition is less than 5% by mass (but does not include 0).

25. The etching composition according to claim 22, wherein the content of water (C2) in 100% by mass of the etching composition is 60% by mass or more.

26. Etching rate ER for silicon at 60°C Ｓｉ２ and the etching rate ER for silicon germanium ＳｉＧｅ２ The etching composition according to claim 19, wherein ER satisfies the following formula (4): Ｓｉ２ / ER ＳｉＧｅ２ ≧35 (4) 27. The etching composition according to claim 19, which is used as an etching composition for dissolving silicon.

28. The etching composition according to claim 19, which dissolves a Si (100) surface after etching at 60°C for 5 minutes so that the average surface roughness measured along three 1 mm long lines placed parallel to each other at 0.5 cm intervals on the surface is 120 nm or less.

29. An etching method for etching a silicon-containing structure using the etching composition according to any one of claims 19 to 28.

30. Using the etching composition according to any one of claims 19 to 28, ２ An etching method comprising the above step of etching the silicon surface.

31. A method for manufacturing a semiconductor device, comprising the step of etching a silicon-containing structure using the etching composition according to any one of claims 19 to 28.

32. A method for manufacturing a transistor, comprising the step of etching a silicon surface of a silicon-containing structure using the etching composition according to any one of claims 19 to 28.

33. The method for manufacturing a transistor according to claim 32, wherein the silicon surface is the surface on the Si layer side in a stack of a SiGe layer and a Si layer.

34. A method for producing a transistor having a BSPDN structure, comprising the step of etching a silicon-containing structure using the etching composition according to any one of claims 19 to 28.

35. An etching method comprising: using a composition containing an alkaline compound (A2), an organic reducing agent (excluding a thiol compound (D2)) (B2), and a thiol compound (D2), wherein the mass ratio of the thiol compound (D2) to the alkaline compound (A2) ((D2) / (A2)) is 0.5 or less, for etching to selectively dissolve silicon relative to silicon germanium.

36. Use of a composition comprising an alkaline compound (A2), an organic reducing agent (excluding a thiol compound (D2)) (B2), and a thiol compound (D2), wherein the mass ratio of the thiol compound (D2) to the alkaline compound (A2) ((D2) / (A2)) is 0.5 or less, in etching that selectively dissolves silicon relative to silicon germanium.

37. An etching composition comprising an alkaline compound (A3) and an organic reducing agent (B3), which dissolves a Si(100) surface after etching at 60°C for 5 minutes so that the average surface roughness measured along three 1 cm long lines placed parallel to each other at 0.5 cm intervals on the surface is 80 nm or less.

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