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

Abstract

Provided are an etching composition which is suitable for manufacturing BSPDN, a method for manufacturing the etching composition, an etching method in which the etching composition is used, a method for manufacturing a semiconductor device, a method for manufacturing a transistor with a BSPDN structure, and use of the composition. The etching composition containing an alkaline compound (A), and at least one of perchloric acid, persulfate, and perchlorate ion (component (B)), and selectively dissolving silicon with respect to silicon germanium.

Description

Etching composition, method for producing etching composition, etching method, method for producing semiconductor device, method for producing transistor, and use of composition

[0001] The present invention relates to an etching composition, a method for producing an etching composition, an etching method, a method for producing a semiconductor device, a method for producing a transistor and the use of the composition.

[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 a step of laminating a silicon wafer with a device surface to another silicon wafer, and then etching and thinning the silicon layer of the wafer opposite the device surface. During this process, a SiGe layer is provided in advance as a stop layer to stop the etching. Therefore, the manufacturing of BSPDN requires an etching composition that selectively dissolves Si relative to SiGe. Furthermore, to increase productivity in the etching process after thinning the silicon layer, an etching composition that provides excellent flatness to the silicon surface after etching is required.

[0009] The present invention has been made in view of the above problems, and an object of the present invention is to provide an etching composition suitable for producing BSPDN. Another object of the present invention is to provide a method for producing the etching composition, an etching method using the etching composition, a method for producing a semiconductor device, a method for producing a transistor having a BSPDN structure, and use of the composition.

[0010] As a result of extensive research, the present inventors have found that an etching composition containing an alkaline compound (A) and an oxidizing agent (B) has excellent selective solubility of silicon relative to silicon germanium. They have also found that an etching composition containing an alkaline compound (A) and an oxidizing agent (B) has excellent flatness of the silicon surface after etching. 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 an alkaline compound (A) and at least one of persulfonic acid, persulfate, and persulfate ions (component (B)), which selectively dissolves silicon relative to silicon germanium. [2] An etching composition comprising an alkaline compound (A) and at least one of persulfonic acid, persulfate, and persulfate ions (component (B)), which dissolves a Si(100) surface after etching at 60°C for 5 minutes such that the average surface roughness measured on three 1-mm-long lines spaced 0.5 cm apart on the surface is 80 nm or less. [3] The etching composition according to [1] or [2] above, wherein the alkaline compound (A) 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] above, wherein the alkaline compound (A) comprises a quaternary ammonium hydroxide compound. [5] The etching composition according to any one of [1] to [4] above, further comprising water. [6] The etching composition according to any one of [1] to [5] above, further comprising an electrolyte (D). [7] The etching composition according to [6] above, wherein the electrolyte (D) comprises at least one of a halide ion source and a halogen anion. [8] The etching composition according to any one of [1] to [7] above, wherein the content of the alkaline compound (A) in 100% by mass of the etching composition is 0.1% by mass or more and less than 40% by mass. [9] The etching composition according to any one of [1] to [8] above, wherein the content of the component (B) in 100% by mass of the etching composition is 0.01% by mass to 20% by mass.

[10] The etching composition according to any one of [6] to [9] above, wherein the content of the electrolyte (D) in 100% by mass of the etching composition is 0.05% by mass to 20% by mass.

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

[10] , wherein ER satisfies the following formula (4): Ｓｉ / ER ＳｉＧｅ≧35 (4)

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

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

[13] The etching composition according to any one of the above [1] to

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

[14] A method for producing the etching composition according to any one of the above [5] to

[13] , comprising a step of dissolving the powdered component (B) in the water.

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

[13] .

[16] A method for etching a silicon-containing structure using the etching composition according to any one of the above [1] to

[13] , wherein the etching composition is used to etch a silicon-containing structure by etching ... ２An etching method comprising the step of etching the silicon surface.

[17] 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

[13] above.

[18] 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

[13] above.

[19] 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

[13] above.

[20] An etching method using a composition containing an alkaline compound (A) and at least one of persulfuric acid, a persulfate salt, and a persulfate ion (component B) for etching to selectively dissolve silicon relative to silicon germanium.

[21] Use of a composition containing an alkaline compound (A) and at least one of persulfuric acid, a persulfate salt, and a persulfate ion (component B) for selectively dissolving silicon relative to silicon germanium.

[22] An etching composition containing an alkaline compound (A) and an oxidizing agent (B) for selectively dissolving silicon relative to silicon germanium.

[23] A dissolution rate control method for changing the dissolution rate of at least one element on the surface of a substrate containing two or more elements in the same solvent, the method comprising controlling the charge of the at least one element on the surface of the substrate to cause the element to adsorb an adsorbate, thereby changing the dissolution rate of the element to which the adsorbate has been adsorbed.

[24] The dissolution rate control method according to

[23] , wherein the dissolution rate is the rate at which the element is dissolved by an etching solution.

[25] The dissolution rate control method according to

[23] or

[24] , wherein the charge of the element on the surface is controlled by replacing a substituent bonded to the element with an anionic substituent.

[26] The dissolution rate control method according to any one of

[23] to

[25] , wherein the two or more elements include at least silicon (Si) and germanium (Ge).

[27] The anionic substituent is O －

[28] The dissolution rate control method according to any one of

[25] to

[27] , wherein the change to anionic substituents is carried out with an oxidizing agent.

[29] The dissolution rate control method according to

[28] , wherein the oxidizing agent is ammonium persulfate.

[30] The dissolution rate control method according to any one of

[23] to

[29] , wherein the adsorbate is a cationic compound.

[31] The dissolution rate control method according to

[30] , wherein the cationic compound is tetramethylammonium cation.

[32] A substrate surface-treated by the dissolution rate control method according to any one of

[23] to

[31] .

[0012] According to the present invention, it is possible to provide an etching composition suitable for producing BSPDN, as well as a method for producing the etching composition, an etching method using the etching composition, a method for producing a semiconductor device, a method for producing a transistor having a BSPDN structure, and use of the composition.

[0013] It is a conceptual diagram for explaining the dissolution rate control method of the present embodiment. It is a diagram for explaining the adsorption of an element on the surface of a substrate and an adsorbate. It is a graph showing the results of an example.

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

[0015] [Etching Composition According to First Aspect] The etching composition according to the first aspect of the present invention comprises an alkaline compound (A) (hereinafter, sometimes referred to as "component (A)") and at least one of persulfate, persulfate, and persulfate ion (hereinafter, sometimes referred to as "component (B)"), and is characterized by selectively dissolving silicon relative to silicon germanium. The etching composition of the present invention preferably further comprises water (hereinafter, sometimes referred to as "component (C)") and an electrolyte (hereinafter, sometimes referred to as "component (D)").

[0016] (Component (A)) The component (A) is an alkaline compound. When the etching composition of the present invention contains the alkaline compound (A), it exhibits excellent silicon solubility.

[0017] Examples of component (A) include organic alkali compounds such as quaternary ammonium hydroxide compounds such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, and ethyltrimethylammonium 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 Bronsted bases such as inorganic alkali compounds and 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.

[0018] The content of component (A) is preferably 0.1 mass% or more, more preferably 0.2 mass% or more, even more preferably 0.5 mass% or more, and particularly preferably 1.5 mass% or more, relative to 100 mass% of the etching composition, because of its excellent solubility in silicon. The content of component (A) is preferably less than 40 mass%, more preferably less than 35 mass%, and even more preferably less than 30 mass% relative to 100 mass% of the etching composition, because of its excellent solubility in water.

[0019] (Component (B)) Component (B) is at least one of persulfuric acid, persulfate salts, and persulfate ions. The inclusion of component (B) in the etching composition of the present invention promotes protection of silicon germanium. Component (B) preferably includes, for example, at least one of peroxodisulfuric acid, peroxodisulfate salts, and peroxodisulfate ions. Specifically, ammonium peroxodisulfate (ammonium persulfate), sodium persulfate, and potassium persulfate can be used, with ammonium peroxodisulfate (ammonium persulfate) being particularly preferred. Furthermore, other component (B) preferably includes at least one of peroxomonosulfuric acid, peroxomonosulfate, and peroxomonosulfate ions.

[0020] Moreover, an oxidizing agent other than those mentioned above can be used as component (B). When the etching composition of the present invention contains an oxidizing agent (B), protection of silicon germanium is promoted.

[0021] Examples of other components (B) include inorganic oxidizing agents such as hydrogen peroxide, chlorous acid or its salts, bromic acid or its salts, chromic acid or its salts, perchloric acid or its salts, and nitric acid or its salts; and organic oxidizing agents such as dimethyl sulfoxide, trimethylamine-N-oxide, and metachloroperbenzoic acid. These components (B) may be used alone or in combination of two or more. Among these components (B), dimethyl sulfoxide is preferred because of its high protective power for silicon germanium.

[0022] The content of component (B) 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 for silicon germanium. Because it provides excellent silicon solubility, it is preferably 0.1 mass% or more, more preferably 0.5 mass% or more, and particularly preferably 1.5 mass% or more. Because it provides excellent silicon dissolution, the content of component (B) 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. Furthermore, because it provides excellent silicon etching durability, it is preferably 10 mass% or less, more preferably 5 mass% or less, and even more preferably 1.5 mass% or less. From the viewpoint of silicon solubility, the content of component (B) is preferably 0.1 mass% or more to 20 mass% or less, more preferably 0.5 mass% or more to 18 mass% or less, and even more preferably 1.5 mass% or more to 15 mass% or less. From the viewpoint of silicon etching continuity, the concentration is preferably 0.01 mass % or more and 10 mass % or less, more preferably 0.05 mass % or more and 5 mass % or less, and even more preferably 0.08 mass % or more and 1.5 mass % or less. Note that etching continuity means that the etching rate after etching is continued for a certain period of time does not change significantly from the etching rate at the start of etching.

[0023] (Component (C)) The etching composition of the present invention preferably contains water (component (C)) in addition to components (A) and (B).

[0024] 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.

[0025] (Component (D)) The etching composition of the present invention preferably further contains an electrolyte (component (D)). By containing component (D), the solubility of silicon can be improved and the protection of silicon germanium can be promoted, thereby obtaining high selective solubility. Furthermore, even when etching progresses, the dissolution rate of silicon can be stabilized. In the present invention, the electrolyte (component (D)) refers to a compound that ionizes in the etching composition, and is a compound excluding the above-mentioned components (A), (B), and (C).

[0026] The component (D) preferably contains at least one of a halide ion source and a halogen anion, such as tetramethylammonium fluoride (TMAF) or ammonium fluoride (NH ４ F), tetramethylammonium chloride (TMACl), ammonium chloride (NH ４ Cl), tetramethylammonium bromide (TMABr), ammonium bromide (NH ４ Br). These components (D) may be used alone or in combination of two or more. Among these components (D), those containing at least one of a fluoride ion source and a fluoride anion in which the halogen is fluorine are preferred, as they improve the solubility of silicon and promote the protection of silicon germanium, and tetramethylammonium fluoride and ammonium fluoride are particularly preferred.

[0027] The content of component (D) is preferably 0.05 mass% or more, more preferably 0.1 mass% or more, and even more preferably 0.5 mass% or more, relative to 100 mass% of the etching composition, because it improves the solubility of silicon and promotes the protection of silicon-germanium. Also, the content of component (D) is preferably 20 mass% or less, more preferably 15 mass% or less, even more preferably 10 mass% or less, and particularly preferably 5 mass% or less, relative to 100 mass% of the etching composition, because it improves the solubility of silicon and promotes the protection of silicon-germanium.

[0028] (Other Components) The etching composition of the present invention may contain other components in addition to the components (A), (B), (C), and (D), 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.

[0029] <Chelating Agent> When the etching composition of the present invention contains a chelating agent, the effect of protecting silicon germanium is exhibited.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] When the etching composition of the present invention 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.

[0034] <Water-miscible solvent> When the etching composition of the present invention contains a water-miscible solvent, it exhibits the effect of making a hydrophobic substance that is not miscible with water miscible with water.

[0035] 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.

[0036] Examples of water-miscible solvents include polar protic solvents such as isopropanol, ethylene glycol, propylene glycol, methanol, ethanol, propanol, butanol, glycerol, and 2-(2-aminoethoxyethanol); polar aprotic solvents such as acetone, dimethyl sulfoxide, N,N-dimethylformamide, N-methylpyrrolidone, and acetonitrile; and nonpolar solvents such as hexane, benzene, toluene, and diethyl ether. These water-miscible solvents may be used alone or in combination of two or more.

[0037] In the etching composition of the present invention, the content of the water-miscible solvent is preferably 5% by mass or less, and more preferably 1% by mass or less, based on 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).

[0038] Furthermore, in the etching composition of the present invention, the content of organic solvent in 100% by mass of the etching composition is preferably less than 5% by mass, more preferably less than 0.5% by mass, and even more preferably substantially free of organic solvent. Note that "substantially free of organic solvent in the etching composition" means that no organic solvent is used as a raw material when producing the etching composition, but does not mean that the etching composition does not contain organic solvents contained in other raw materials. In addition, in this specification, organic solvent refers to organic solvents excluding the above-mentioned water-miscible solvents.

[0039] From the viewpoint of selective solubility of silicon in silicon germanium, the amount of any other component other than the component (A), the component (B), the component (C), and the component (D) is preferably 10 mass % or less, more preferably 5 mass % or less, and even more preferably zero, of 100 mass % of the etching composition.

[0040] (Mass Ratio of Each Component) The mass ratio of the content of component (B) to the content of component (A) in the etching composition of the present invention (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.

[0041] When the etching composition of the present invention contains component (C), the ratio of the content of component (A) to the content of component (C) in terms of mass ratio (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 order to achieve excellent silicon solubility.

[0042] When the etching composition of the present invention contains component (C), the ratio of the content of component (B) to the content of component (C) in terms of mass ratio (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.

[0043] When the etching composition of the present invention contains component (D), the ratio of the content of component (D) to the content of component (B) in terms of mass ratio (mass of component (D) / mass of component (B), hereinafter referred to as "(D) / (B)") is preferably 1,000 or less, more preferably 0.001 to 100, and even more preferably 0.001 to 10.

[0044] (Method for Producing Etching Composition) The method for producing the etching composition of the present invention is not particularly limited, and the etching composition can be produced by mixing component (A), component (B), and, as necessary, component (C), component (D), and other components. The order of mixing is not particularly limited, and all components may be mixed at once, or some components may be mixed in advance and then the remaining components may be mixed. However, it is preferable to have a step of dissolving powdery component (B) in component (C).

[0045] (Physical Properties of Etching Composition) The pH of the etching composition of the present invention is preferably 8 to 14, more preferably 9 to 14, and even more preferably 10 to 14, in view of excellent silicon solubility.

[0046] Silicon etch rate ER of the etching composition of the present invention Ｓｉ The ER (nm / min) is preferably 50 nm / min or more, more preferably 100 nm / min or more, even more preferably 150 nm / min or more, particularly preferably 200 nm / min or more, particularly preferably 250 nm / min or more, and most preferably 300 nm / min or more, because the selective solubility of silicon in silicon germanium is excellent. That is, it is more preferable that the following formula (5) is satisfied. Ｓｉ ≧50 (5) where the silicon etch rate ER 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.

[0047] The silicon germanium etch rate ER of the etching composition of the present invention ＳｉＧｅ The ER (nm / min) is preferably 10 nm / min or less, more preferably 8 nm / min or less, even more preferably 5 nm / min or less, and particularly preferably 3 nm / min or less, because this provides excellent selective solubility of silicon in silicon germanium. That is, it is particularly preferable that the following formula (6) is satisfied: ＳｉＧｅ ≦10 (6)

[0048] The dissolution selectivity (ER) of the etching composition of the present invention 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 (4): Ｓｉ / ER ＳｉＧｅ ≧35 (4) The dissolution selectivity ratio is more preferably 50 or more, further preferably 70 or more, particularly preferably 150 or more, particularly preferably 250 or more, and most preferably 500 or more.

[0049] Etch Rate ER Ｓｉ , etch rate ER ＳｉＧｅ The dissolution selectivity ratio is measured and calculated by the method described in the Examples below.

[0050] (Target to be etched by the etching composition) The etching composition of the present invention inhibits dissolution of silicon germanium, promotes dissolution of silicon, and exhibits excellent selective solubility of silicon relative to silicon germanium. Therefore, the etching composition of the present invention is suitable for etching structures containing silicon and silicon germanium, such as semiconductor devices, and is particularly suitable for structures containing silicon and silicon germanium used in forming a BSPDN structure. The structure containing silicon and silicon germanium used in forming a BSPDN structure is a structure containing two silicon layers and a silicon germanium layer therebetween. When etching this structure, the etching composition of the present invention first etches the first silicon layer. When the first silicon layer is etched, the silicon germanium layer between them is exposed, and the etching composition of the present invention primarily etches the first silicon layer by selectively dissolving silicon relative to silicon germanium. This allows a structure containing a second silicon layer and a silicon germanium layer to be obtained from a structure containing two silicon layers and a silicon germanium layer therebetween.

[0051] The silicon content in the silicon germanium to be etched is preferably 10 mass% or more, more preferably 20 mass% or more, based on 100 mass% of silicon germanium, since this is suitable for etching with the etching composition of the present invention. The silicon content in the silicon germanium to be etched is preferably 98 mass% or less, more preferably 95 mass% or less, based on 100 mass% of silicon germanium, since this is suitable for etching with the etching composition of the present invention.

[0052] The content of germanium in the silicon germanium to be etched is preferably 2 mass% or more, more preferably 5 mass% or more, based on 100 mass% of silicon germanium, since this is suitable for etching with the etching composition of the present invention. The content of germanium in the silicon germanium to be etched is preferably 90 mass% or less, more preferably 80 mass% or less, based on 100 mass% of silicon germanium, since this is suitable for etching with the etching composition of the present invention.

[0053] The silicon germanium alloy 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 the transistor is formed.

[0054] In a structure containing silicon and silicon germanium or a structure in which silicon and silicon germanium are stacked, silicon oxide may be exposed.

[0055] (Etching Method) The etching method of the present invention is a method of etching a structure containing silicon and silicon germanium using the etching composition of the present invention.

[0056] The etching method can be a known method, such as a batch method or a single wafer method.

[0057] 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.

[0058] The structure containing silicon and silicon germanium is 1 mm ２ The etching method of the present invention is ２ It is preferable that the method includes an etching step of etching the silicon surface. Furthermore, it is preferable that the structure containing silicon and silicon germanium is a laminate of a SiGe layer and a Si layer, and that the silicon surface is formed on the Si layer side of this laminate.

[0059] [Etching Composition According to Second Aspect] The etching composition according to the second aspect of the present invention comprises an alkaline compound (A) (“component (A)”) and an oxidizing agent (B) (“component (B)”), 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.

[0060] The etching composition of the present invention is preferably a composition that 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 50 nm or less, more preferably a composition that dissolves the surface so that the average surface roughness is 30 nm or less, even more preferably a composition that dissolves the surface so that the average surface roughness is 20 nm or less, even more preferably a composition that dissolves the surface so that the average surface roughness is 15 nm or less, and particularly preferably a composition that dissolves the surface so that the average surface roughness is 10 nm or less.

[0061] In the etching composition according to the second embodiment of the present invention, the details of the contained component (A) and component (B), the details of the component (C), component (D) and other components that may be contained as optional components, the mass ratio of each component, the method for producing the etching composition, the physical properties of the etching composition, the target to be etched, the etching method, and the like can be applied to the etching composition according to the first embodiment of the present invention described above.

[0062] The etching composition according to the first and second aspects of the present invention and the etching method according to the present invention can be suitably used in the manufacture of semiconductor devices, which includes a step of etching a structure containing silicon and silicon germanium. In particular, since the etching composition suppresses dissolution of silicon germanium, promotes dissolution of silicon, and exhibits excellent selective solubility of silicon relative to silicon germanium, the etching composition is suitable for a transistor manufacturing method, which includes a step of etching a silicon-containing structure, and further, the etching method can be particularly suitably used in a transistor manufacturing method, which includes a step of etching a silicon-containing structure, and in the manufacture of a device having a BSPDN structure, which includes a step of etching a structure containing silicon and silicon germanium.

[0063] The etching composition of the present invention has excellent selective solubility of silicon relative to silicon germanium. Furthermore, the etching composition of the present invention has excellent flatness of the silicon surface after etching. Due to these properties, the etching composition of the present invention can be suitably used for manufacturing BSPDN. 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 having a BSPDN structure of the present invention can perform highly accurate etching in the etching step to manufacture desired products with a high yield.

[0064] [Dissolution Rate Control Method] Next, a method for controlling the dissolution rate of etching using the etching composition of the present invention will be described. The dissolution rate control method of this embodiment is a method for changing the dissolution rate of at least one element on the surface of a substrate containing two or more elements in the same solvent, and involves controlling the charge of at least one element on the surface of the substrate to cause the element to adsorb an adsorbate, thereby changing the dissolution rate of the element to which the adsorbate has adsorbed. This makes it possible to change the dissolution rate of the substrate.

[0065] The dissolution rate control method of this embodiment will be described below with reference to an embodiment in which a substrate having a silicon and silicon germanium layer stacked thereon is dissolved by etching, which is performed in the BSPDN manufacturing process. In the BSPDN manufacturing process, a silicon wafer having a device surface formed thereon is bonded to another silicon wafer, and then the silicon layer of the wafer opposite the device surface is etched to thin it. Therefore, from the viewpoint of shortening the time required to etch the silicon layer, it is preferable that the dissolution rate of the etching solution for silicon be fast. Furthermore, a silicon germanium layer is provided on the substrate as a stop layer to stop etching of the silicon layer.

[0066] FIG. 1 is a conceptual diagram illustrating the dissolution rate control method of this embodiment. In the manufacturing process of BSPDN, when a silicon layer is etched, the silicon germanium layer is reached as shown in FIG. 1. The silicon germanium layer shown in FIG. 1 is a layer in which the ratio of silicon to germanium is 3:1, so three silicon atoms and one germanium atom are shown. On the surface of the silicon germanium layer, hydrogen (-H) or hydroxyl groups (-OH) are bonded to the silicon or germanium, and hydroxide ions (OH) in the alkaline compound of the etching solution are bonded to the silicon germanium layer. － ) and water act as reactive species, and etching of the silicon germanium layer proceeds.

[0067] Therefore, in the dissolution rate control method of this embodiment, the charge of the element (germanium) on the substrate surface is controlled to cause the element to adsorb the adsorbate, as shown in Figure 1. As a result, the element to which the adsorbate has been adsorbed is prevented from coming into contact with the reactive species due to the adsorbate, and the dissolution rate changes (slows down), slowing down the dissolution rate of the silicon germanium layer. As a result, the silicon germanium layer serves as a stop layer for etching by the etching solution.

[0068] The charge of an element on the substrate surface can be controlled by replacing the substituent bonded to the element with an anionic substituent, as shown in FIG. 2. When the substituent is hydrogen, etching proceeds due to weak adsorption to the cationic compound (tetramethylammonium cation). By using an anionic substituent, adsorption to the cationic compound can be strengthened, preventing etching and slowing down the dissolution rate. Examples of anionic substituents include O － , F － , Cl － ,Br － Among them, from the viewpoint of adsorption to the adsorbed substance and ease of substitution, as shown in FIG. － In the case of silicon and germanium, the anionic substituents of the substituents bonded to the elements are more easily substituted by germanium than by silicon. Therefore, the adsorbed substance is more easily adsorbed by germanium than by silicon, and the dissolution rate of germanium can be changed.

[0069] The substitution of anionic substituents for substituents bonded to elements is preferably carried out using an oxidizing agent. Therefore, the etching solution preferably contains an oxidizing agent. By using an oxidizing agent contained in the etching solution, the substituents bonded to germanium can be replaced with anionic substituents at the time when etching of the silicon layer is completed, and the adsorbed substance is adsorbed, thereby slowing down the reaction rate. As the oxidizing agent, ammonium persulfate, dimethyl sulfoxide, trimethylamine-N-oxide, etc. are preferably used. Among them, ammonium persulfate is preferably used from the viewpoint of being able to replace only the substituents of elements on the surface of the substrate with anionic substituents.

[0070] By replacing the substituents bonded to the elements on the substrate surface with anionic substituents, it is possible to adsorb the anionic substituents and a cationic compound as the adsorbate. The cationic compound is preferably a salt of an alkaline compound contained in the etching solution, and more preferably a salt of a quaternary ammonium hydroxide compound. Among these, tetramethylammonium cations are preferred from the viewpoint of adsorption.

[0071] As described above, according to the dissolution rate control method of this embodiment, the charge of the element on the substrate surface is controlled to adsorb the adsorbate, thereby changing the dissolution rate of the element. Therefore, the dissolution rate of the substrate can be controlled, and at least one element out of two or more elements can be selectively dissolved during etching.

[0072] [Etching Solution] The etching solution used in the above-mentioned dissolution rate control method can be the etching composition described above.

[0073] The dissolution rate control method of this embodiment can be suitably used in the manufacture of semiconductor devices, which includes a step of etching a structure containing silicon and silicon germanium, and in particular, in the manufacture of devices having a BSPDN structure, which includes a step of etching a structure containing silicon and silicon germanium.

[0074] Furthermore, the dissolution rate control method can be suitably used in the manufacture of the above-mentioned semiconductor devices and devices having a BSPDN structure, and can also be applied to, for example, the manufacture of semiconductor devices including a cleaning process. When applied to a cleaning process, cleaning can be performed by oxidizing at least one element of two or more elements, protecting it with an adsorbate, and selectively dissolving the other element.

[0075] 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.

[0076] (Raw Materials) The following were used as raw materials for producing the etching compositions in the Examples and Comparative Examples. Component (A-1): Tetramethylammonium hydroxide (TMAH) Component (A-2): Ethyltrimethylammonium hydroxide (ETMAH) Component (B-1): Ammonium persulfate (ammonium peroxodisulfate (APS)) Component (B-2): H ２ O ２ (hydrogen peroxide) Component (B-3): DMSO (dimethyl sulfoxide) Component (B-4): benzoquinone Component (B-5): NaClO (sodium hypochlorite) Component (B-6): H ５ IO ６ (orthoperiodic acid) Component (D-1): tetramethylammonium fluoride (TMAF) Component (D-2): ammonium fluoride (NH ４ F)

[0077] <Silicon Etch Rate and Surface Flatness> A silicon substrate having a film thickness of 0.75 mm and a size of 20 mm x 20 mm square 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 in the etching compositions obtained in the Examples and Comparative Examples at 60°C. The immersion time was 5 minutes for the Examples and Comparative Examples 4 and 5, and 3 minutes for the other Comparative Examples. The film thickness with and without masking was measured with a contact step gauge, and the silicon etch rate ER was calculated using the following formula (1): Ｓｉ [nm / min] was calculated. Ｓｉ[nm / min] = (silicon film thickness with masking - silicon film thickness without masking) ÷ immersion time (1) The silicon surface roughness after immersion was measured using a contact profilometer. The surface flatness was expressed as the average value of the surface roughness measured on three 1 mm long line segments arranged parallel to each other at 0.5 cm intervals on the silicon (100) surface.

[0078] <Silicon Germanium Etch Rate> A substrate on which a 50 nm thick silicon germanium layer was laminated was immersed in a 0.5 mass % hydrofluoric acid aqueous solution for 60 seconds, then rinsed with ultrapure water, and then immersed in the etching compositions obtained in the Examples and Comparative Examples at 60°C. The immersion time was 5 minutes in the Examples and Comparative Examples 4 and 5, and 3 minutes in the other 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 formula (2): ＳｉＧｅ [nm / min] was calculated. ＳｉＧｅ [nm / min] = (silicon germanium film thickness before immersion - silicon germanium film thickness after immersion) ÷ immersion time (2)

[0079] <Dissolution Selectivity Ratio of Silicon to Silicon Germanium> The dissolution selectivity ratio of silicon to silicon germanium was calculated using the following formula (3): Dissolution Selectivity Ratio = ER Ｓｉ [nm / min]÷ER ＳｉＧｅ [nm / min] (3)

[0080] [Example 1] An etching composition was obtained by mixing the components so that, based on 100 mass% of the etching composition, 2.28 mass% of component (A-1), 1.0 mass% of component (B-1), and the remainder was water. The evaluation results of the obtained etching composition are shown in Table 1.

[0081] [Examples 2 to 5] Etching compositions were obtained in the same manner as in Example 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 and FIG.

[0082] Comparative Examples 1 to 9 Etching compositions were obtained in the same manner as in Example 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 and FIG.

[0083]

[0084] As can be seen from Table 1, the etching compositions obtained in the Examples were remarkably excellent in the selective solubility of silicon relative to silicon germanium. Furthermore, the etching compositions obtained in the Examples were excellent in the flatness of the silicon (100) surface after etching. On the other hand, the etching compositions obtained in Comparative Examples 1 to 3 were inferior in the selective solubility of silicon relative to silicon germanium. Furthermore, the etching compositions obtained in the Comparative Examples were inferior in the flatness of the silicon (100) surface after etching.

[0085] As shown in Table 1 and Figure 3, in Examples 1 to 3, which contain ammonium persulfate as the oxidizing agent (B), the substituents bonded to germanium by the oxidizing agent are replaced with anionic substituents in the substrate on which silicon germanium is laminated. The anionic substituents then adsorb the tetramethylammonium cations of the alkaline component (A) as adsorbates, thereby reducing the etching rate of silicon germanium compared to Comparative Example 1, which does not contain ammonium persulfate, and increasing the selective solubility of silicon in silicon germanium.

[0086] Furthermore, the etching compositions obtained in Comparative Examples 4 to 10, in which component (B) was a component other than ammonium persulfate, were inferior in selective solubility of silicon relative to silicon germanium compared to the Examples.

[0087] 3 is a graph showing the etching rates of Si and SiGe and the Si / SiGe selectivity for Examples 1 to 3 and Comparative Example 2. As shown in FIG. 3, in Examples 1 to 3 containing ammonium persulfate, in a substrate on which silicon germanium is stacked, the substituents bonded to germanium by the oxidizing agent are replaced with anionic substituents. Furthermore, because the anionic substituents adsorb the tetramethylammonium cations of the alkaline component (A) as adsorbates, the etching rate of silicon germanium can be reduced compared to Comparative Example 1, which does not contain ammonium persulfate, and the selective solubility of silicon in silicon germanium can be increased.

[0088] [Examples 6 and 7] Etching compositions were obtained in the same manner as in Example 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.

[0089]

[0090] It was confirmed that the etching compositions obtained in Examples 6 and 7, which contained an electrolyte (component (D)), had a superior effect in terms of the selective solubility of silicon in silicon germanium compared to Examples 1 and 3, which did not contain component (D). In addition, good results were obtained with respect to the flatness of the silicon (100) surface after etching.

[0091] The etching composition of the present invention has excellent selective solubility of silicon relative to silicon germanium. Furthermore, the etching composition of the present invention has excellent flatness of the silicon (100) surface after etching. For these reasons, the etching composition is particularly suitable as an etching composition used for producing a BSPDN structure.

Claims

1. An etching composition comprising an alkaline compound (A) and at least one of persulfate, persulfate, and persulfate ions (component (B)), which selectively dissolves silicon relative to silicon germanium.

2. An etching composition comprising an alkaline compound (A) and at least one of persulfonic acid, persulfate, and persulfate ions (component (B)), 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 placed parallel to each other at 0.5 cm intervals on the surface is 80 nm or less.

3. The etching composition according to claim 1 or 2, wherein the alkaline compound (A) comprises at least one compound selected from the group consisting of quaternary ammonium hydroxide compounds, amine compounds, and metal hydroxides.

4. The etching composition of claim 1 or 2, wherein the alkaline compound (A) comprises a quaternary ammonium hydroxide compound.

5. The etching composition according to claim 1 or 2, further comprising water.

6. The etching composition according to claim 1 or 2, further comprising an electrolyte (D).

7. The etching composition according to claim 6, wherein the electrolyte (D) contains at least one of a halide ion source and a halogen anion.

8. An etching composition according to claim 1 or 2, wherein the content of the alkaline compound (A) in 100% by mass of the etching composition is 0.1% by mass or more and less than 40% by mass.

9. The etching composition according to claim 1 or 2, wherein the content of component (B) in 100% by mass of the etching composition is 0.01% by mass to 20% by mass.

10. The etching composition according to claim 6, wherein the content of the electrolyte (D) in 100% by mass of the etching composition is 0.05% by mass to 20% by mass.

11. Etching rate for silicon ER Ｓｉ and the etching rate ER for silicon germanium ＳｉＧｅ The etching composition according to claim 1 or 2, wherein ER satisfies the following formula (4): Ｓｉ / ER ＳｉＧｅ ≧35 (4) 12. The etching composition according to claim 1 or 2, which is used as an etching composition for dissolving silicon.

13. The etching composition of claim 1 or 2, wherein the silicon is single crystal silicon.

14. A method for producing an etching composition according to claim 5, comprising the step of dissolving the powdered component (B) in the water.

15. An etching method for etching a silicon-containing structure using the etching composition according to claim 1 or 2.

16. Using the etching composition according to claim 1 or 2, ２ An etching method comprising the above step of etching the silicon surface.

17. A method for manufacturing a semiconductor device, comprising the step of etching a silicon-containing structure using the etching composition of claim 1 or 2.

18. A method for manufacturing a transistor, comprising the step of etching a silicon-containing structure using the etching composition of claim 1 or 2.

19. A method for manufacturing a transistor having a BSPDN structure, comprising the step of etching a silicon-containing structure using the etching composition of claim 1 or 2.

20. An etching method using a composition containing an alkaline compound (A) and at least one of persulfuric acid, persulfate salts, and persulfate ions (component B) for etching to selectively dissolve silicon relative to silicon germanium.

21. Use of a composition comprising an alkaline compound (A) and at least one of persulfuric acid, a persulfate salt, and persulfate ions (component B) for selectively dissolving silicon relative to silicon germanium.

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