Etching method and method for manufacturing semiconductor device

Abstract

To provide an etching method excellent in selective dissolution nature of a 110 surface relative to a 100 surface of a silicon crystal, a method for manufacturing a semiconductor device including the etching method, a method for manufacturing a vertical transistor device, and a method for manufacturing a gate-all-around transistor.SOLUTION: An etching method includes the steps of: (1) oxidizing a surface of a silicon-containing structure; and (2) etching the silicon-containing structure whose surface is oxidized, in succession. A method for manufacturing a semiconductor device including the etching method. A method for manufacturing a vertical transistor device including the etching method. A method for manufacturing a gate-all-around transistor including the etching method.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] In accordance with Moore's Law, integrated circuits are becoming increasingly miniaturized. In recent years, in addition to reducing the size of conventional planar transistors, Transistors (Fin-type FETs) and gate-all-around transistors (GAA-type FETs) T), further miniaturization and integration that change the structure from flat to three-dimensional to improve performance The following transistor structures are expected to be further miniaturized: By changing the structure from the conventional planar transistor to a vertical one, the vertical transistor can be miniaturized and performance can be improved. Vertical transistors (VFETs) are being considered.

[0003] In a GAA FET, a nanosheet or nanowire-shaped channel is covered with a gate electrode. By increasing the contact area between the channel and gate electrode, the number of transistors per unit area can be increased. Improve performance.

[0004] In VFETs, nanosheet or nanowire-like channels are stacked vertically. The area of ​​the standard cell layout is smaller than that of a planar transistor (HFET). This improves the performance of the transistor per unit area.

[0005] To form GAA type FETs and VFETs, an etching method that dissolves silicon is required. As such an etching method, for example, Patent Documents 1 and 2 disclose an etching method using An etching method using an etching solution containing an alkaline compound is disclosed. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2017-108122 A [Patent Document 2] JP 2021-136429 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the etching methods disclosed in Patent Documents 1 and 2, silicon The selective dissolution of the 110 face of a silicon crystal is inferior to that of the 100 face of a silicon crystal.

[0008] In particular, in recent years, there has been a strong demand for miniaturization of FETs, and silicon with narrow gaps of several tens of nanometers It is necessary to control the etching according to the surface orientation. The FET to be fabricated requires the formation of nano-shapes by etching from the horizontal direction. Therefore, there is a need for an etching method that is excellent in selectively dissolving the 110 plane of silicon crystal. In particular, selective dissolution according to surface orientation is easy to control because the surface is composed of the same elements. There is none.

[0009] The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for manufacturing a silicon oxide semiconductor device. A method for selectively dissolving the 110 plane of silicon crystals relative to the 100 plane of silicon crystals has been developed. The purpose is to provide. Another object of the present invention is to provide a method for manufacturing a semiconductor device, comprising the etching method, To provide a method for manufacturing a transistor and a method for manufacturing a gate-all-around transistor The point is that. [Means for solving the problem]

[0010] As a result of intensive research, the present inventors have discovered a process for oxidizing the surface of a silicon-containing structure and and etching the structure containing silicon whose surface is oxidized. However, it has excellent selective solubility in the 110 plane of silicon crystal compared to the 100 plane of silicon crystal. 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 method comprising the following steps (1) and (2) in that order: Step (1): Oxidizing the surface of a silicon-containing structure Step (2): Etching the structure containing silicon having an oxidized surface. [2] The oxidation method in the step (1) comprises treating a silicon-containing structure with an oxidizing agent (A). The etching method according to [1], wherein the etching is carried out by contacting the substrate with a solution containing the metal oxide. [3] The oxidizing agent (A) is hydrogen peroxide, peroxodisulfuric acid, a salt of peroxodisulfuric acid, chlorine [2] containing at least one compound selected from the group consisting of salts of chromate and chromate. The etching method described herein. [4] The etching method according to [2] or [3], wherein the oxidizing agent (A) contains hydrogen peroxide. . [5] The etching method according to any one of [2] to [4], wherein the solution containing the oxidizing agent (A) contains water. Ching method. [6] The content of the oxidizing agent (A) in 100% by mass of the solution containing the oxidizing agent (A) is 0.1 mass% % to 30 mass %. [7] The etching method in step (2) is a method for forming a structure containing silicon having an oxidized surface. Any of [1] to [6], which is a method of contacting the catalyst with a solution containing an alkaline compound (B). The etching method according to any one of the preceding claims. [8] The alkaline compound (B) is a quaternary ammonium hydroxide compound, potassium hydroxide, and and calcium hydroxide. The etching method described above. [9] The alkaline compound (B) includes a quaternary ammonium hydroxide compound; [7] or The etching method according to [8].

[10] The solution containing the alkaline compound (B) contains water, any one of [7] to [9]. The etching method according to claim 1.

[11] Alkaline compound (B) in 100% by mass of a solution containing the alkaline compound (B) [7] to

[10] , wherein the content of Etching method.

[12] Dissolve 110 faces of a silicon crystal for every 100 faces of a silicon crystal.[1] The etching method according to any one of items

[11] to

[11] .

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

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

[14] A semiconductor device, comprising the etching method according to any one of [1] to

[13] . Manufacturing method.

[15] A method for producing a vertical transistor, comprising the etching method according to any one of [1] to

[13] . Manufacturing method of sta.

[16] A gate-all etching method comprising the etching method according to any one of [1] to

[13] . A method for manufacturing a round transistor. Effect of the Invention

[0012] The etching method of the present invention is a method for etching a silicon crystal with a 110 plane relative to a 100 plane. It has excellent selective solubility. The method for manufacturing a semiconductor device of the present invention, the method for manufacturing a vertical transistor of the present invention, and The manufacturing method of the gate-all-around transistor developed by Ming is to fabricate 100 layers of silicon crystals. This method includes an etching method with excellent selective dissolution properties for the 110 plane of silicon crystal, allowing for high precision. By carrying out etching in this manner, the desired product can be manufactured with a high yield. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention will be described in detail below, but the present invention is not limited to the following embodiments. The present invention can be practiced in various modifications within the scope of the spirit of the present invention. When using the expression "~", it is used to include the numerical values ​​or physical properties before and after it.

[0014] (Etching method) The etching method of the present invention includes the following steps (1) and (2) in order to obtain a silicon It has excellent selective solubility in the 110 face of silicon crystals relative to the 100 face of silicon crystals. Step (1): Oxidizing the surface of a silicon-containing structure Step (2): Etching the structure containing silicon having an oxidized surface. The etching method of the present invention is to improve the 110 plane of a silicon crystal compared to the 100 plane of a silicon crystal. The reasons for the excellent selective solubility are considered to be as follows. First, the surface of silicon is oxidized in step (1). The 100 face of the silicon crystal is more easily broken than the 110 face of the crystal. The silicon is etched by the silicon oxide layer, but the etching rate of the silicon is The surface area of ​​the silicon oxide depends on the surface area ratio, and the larger the surface area ratio of the silicon oxide, the slower the reaction. The etching method is selective dissolution of the 110 face of the silicon crystal relative to the 100 face of the silicon crystal. It is considered to have excellent performance.

[0015] (Process (1)) The step (1) is a step of oxidizing the surface of a silicon-containing structure.

[0016] Since the silicon in the silicon-containing structure has a crystal plane orientation, it is single crystal silicon. The single crystal silicon can be produced by a known method, and the single crystal ingot is preferably It may be manufactured by cutting or by epitaxial growth. .

[0017] The silicon-containing structure may also contain a material other than silicon. Examples of the material include silicon germanium, silicon oxide, silicon nitride, and silicon carbon. Nitrides and the like.

[0018] In step (1), the oxidation state of the surface of the silicon-containing structure can be precisely controlled. and a step of removing a native oxide film on the surface of the silicon-containing structure before the step (1). It is preferable. The method for removing the native oxide film on the surface of the silicon-containing structure may be a known method. The method of contacting the catalyst with a fluorine-containing compound is preferred because it has excellent removability of natural oxide films. A method of contacting with an aqueous hydrofluoric acid solution is preferred.

[0019] As a method for oxidizing the surface of a silicon-containing structure, for example, a solution containing an oxidizing agent (A) is used. Examples of such methods include contacting the catalyst with a liquid, contacting the catalyst with oxygen, and electrolytic oxidation. Among these methods, the oxidation degree can be controlled according to the crystal plane orientation of silicon, so the oxidizing agent A method of contacting the solution containing (A) or a method of contacting the solution with oxygen are preferred. A method of contacting the compound with a solution containing the compound is more preferred.

[0020] The oxidizing agent (A) (hereinafter sometimes referred to as "component (A)") may be, for example, peroxide. Hydrogen, peroxodisulfuric acid or its salts, chlorous acid or its salts, bromic acid or its salts, chromic acid or a salt thereof, perchloric acid or a salt thereof, nitric acid or a salt thereof, etc. Among these components (A), one type may be used alone, or two or more types may be used in combination. However, because there are few hazardous reaction products, hydrogen peroxide, peroxodisulfuric acid, Preferred are sulfuric acid, chromic acid, and salts of chromic acid. Hydrogen peroxide, peroxodisulfuric acid, peroxodisulfuric acid, Salts of xodisulfuric acid are more preferred, and hydrogen peroxide is even more preferred.

[0021] The content of component (A) promotes partial oxidation of silicon, so the content of the component (A) in the solution In 100% by mass of the liquid, 0.1% by mass or more is preferable, 0.3% by mass or more is more preferable, and 0.1% by mass or more is more preferable. 0.5 mass% or more is even more preferable. The content of component (A) is high because it inhibits the complete oxidation of silicon. In 100% by mass of the liquid, the amount is preferably 30% by mass or less, more preferably 25% by mass or less, It is more preferable that the amount of the water is 10% or less.

[0022] The solution containing component (A) preferably contains water in addition to component (A).

[0023] The water content is set so that the preparation of a solution containing component (A) is easy and the solubility of component (A) is excellent. Therefore, the content of the component (A) in the solution (100 mass %) is preferably 70 mass % or more, and more preferably 75 mass % or more. % by mass or more is more preferable, and 80% by mass or more is even more preferable. The water content is set to 100% of the solution containing component (A) since it promotes partial oxidation of silicon. In terms of mass%, 99.9 mass% or less is preferable, 99.7 mass% or less is more preferable, and 99. It is more preferably 5% by mass or less.

[0024] The solution containing component (A) may contain, in addition to component (A) and water, any other components within the scope of the present invention. , may contain other ingredients. Examples of other components include a pH adjuster and a surfactant.

[0025] The effect of controlling the oxidation rate of silicon by including a pH adjuster in the solution containing component (A) is expressed.

[0026] Examples of pH adjusters include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid; citric acid, and acetic acid. , oxalic acid, formic acid and other organic acids; sodium hydroxide, potassium hydroxide, calcium hydroxide, Inorganic alkali such as ammonium hydroxide; tetramethylammonium hydroxide, tetramethylammonium hydroxide, Organic ammonium hydroxide such as ethyl ammonium hydroxide and tetrabutyl ammonium hydroxide These pH adjusters may be used alone or in combination of two or more. may be used.

[0027] When the solution containing component (A) contains a pH adjuster, the content of the pH adjuster is In 100% by mass of the solution, the content is preferably 30% by mass or less, more preferably 20% by mass or less. It is more preferably 10% by mass or less.

[0028] The method for producing the solution containing component (A) is not particularly limited. It can be produced by mixing it with other ingredients. The order of mixing is not particularly limited. All the components may be mixed at once, or some of the components may be mixed at once. The remaining ingredients may be premixed and then mixed.

[0029] The method for contacting the silicon-containing structure with the solution containing component (A) can be, for example, a method of immersing a silicon-containing structure in a solution containing component (A); and a method of spin-coating a solution containing component (A) onto the substrate. In addition, the contact uniformity between the surface of the silicon-containing structure and the solution containing component (A) is excellent. Therefore, a method of immersing a silicon-containing structure in a solution containing component (A) is preferred.

[0030] The time for which the silicon-containing structure is immersed in the solution containing component (A) is determined based on the partial oxidation of silicon. In order to promote the polymerization, the reaction time is preferably 0.5 minutes or more, and more preferably 1 minute or more. The time for which the silicon-containing structure is immersed in the solution containing component (A) is determined based on the complete oxidation of the silicon. In order to suppress oxidation, the time is preferably 30 minutes or less, and more preferably 10 minutes or less.

[0031] The temperature at which the silicon-containing structure is immersed in the solution containing component (A) is In order to promote partial oxidation, a temperature of 15° C. or higher is preferable, and 20° C. or higher is more preferable. The temperature at which the silicon-containing structure is immersed in the solution containing component (A) is set to a value that satisfies the complete dissolution of silicon. In order to suppress total oxidation, the temperature is preferably 100° C. or lower, and more preferably 80° C. or lower. The temperature at which the silicon-containing structure is immersed in the solution containing component (A) is determined based on the temperature at which the silicon-containing structure is immersed in the solution containing component (A). This corresponds to the temperature of the solution containing component (A).

[0032] The method for immersing the silicon-containing structure in the solution containing component (A) may be a known method. For example, a batch type, a single wafer type, etc. can be mentioned.

[0033] (Process (2)) Step (2) is a step of etching the structure containing silicon whose surface is oxidized.

[0034] As a method for etching a structure containing silicon with an oxidized surface, for example, a method of contacting the compound (B) with a solution containing an alkaline compound; and a method of contacting the compound (B) with a solution containing an acidic compound. Among these methods, the method of etching silicon and silicon oxide is the most popular. Since it has excellent dissolution selectivity with cation oxides, it is highly soluble in water when it comes into contact with a solution containing an alkaline compound (B). The method of soaking in a solution containing an alkaline compound (B) or dry etching is preferred. The contacting method is more preferred.

[0035] Examples of the alkaline compound (B) (hereinafter sometimes referred to as "component (B)") include For example, tetramethylammonium hydroxide, tetraethylammonium hydroxide, Organic alkoxides such as quaternary ammonium hydroxide compounds such as tetrabutylammonium hydroxide Potash compounds; metal hydroxides such as sodium hydroxide, potassium hydroxide, calcium hydroxide, etc. The inorganic alkali compounds may be used alone as the component (B). Among these components (B), those that have an effect on the transistor performance are Because of the low content of sodium, which is easily dissolved in water, quaternary ammonium hydroxide compounds, cation hydroxide sodium hydroxide, calcium hydroxide, and more preferably quaternary ammonium hydroxide compounds; Tetramethylammonium hydroxide and tetrabutylammonium hydroxide are also preferable.

[0036] The content of component (B) is 1:1 because of its excellent solubility in silicon. Of the 00% by mass, 0.01% by mass or more is preferable, 0.03% by mass or more is more preferable, and More preferably, it is .05% by weight or more. The content of component (B) is 100% of the solution containing component (B) because of its excellent solubility in water. In terms of mass%, it is preferably 30 mass% or less, more preferably 25 mass% or less, and more preferably 20 mass% or less. is more preferred.

[0037] The solution containing component (B) preferably contains water in addition to component (B).

[0038] The water content is set so that the preparation of a solution containing component (B) is easy and the solubility of component (B) is excellent. Therefore, the amount of component (B) is preferably 70% by mass or more, and more preferably 75% by mass or more, based on 100% by mass of the solution containing component (B). % by mass or more is more preferable, and 80% by mass or more is even more preferable. The content of water is 100 mass % of the solution containing component (B) because water has excellent solubility in silicon. %, preferably 99.99 mass% or less, more preferably 99.97 mass% or less, and 99. It is more preferably 95% by mass or less.

[0039] The solution containing component (B) may contain any other components other than component (B) and water, provided that the effects of the present invention are not impaired. , may contain other ingredients. Examples of other components include surfactants and water-miscible solvents.

[0040] The solution containing component (B) contains a surfactant, which allows the silicon to be adsorbed and protected according to its crystal plane orientation. The effect of is exerted.

[0041] Examples of surfactants include octylphenol ethoxylate and polyethylene glycol. Cholesterol mono-4-nonylphenyl ether, polyoxyethylene lauryl ether, poly Nonionic surfactants such as ethylene glycol; hexadecyltrimethylammonium bromide octadecyltrimethylammonium bromide, didecyldimethylammonium bromide Bromide, Tetradecylammonium Bromide, Benzyldimethylstearylammonium Chloride, Hexadecylpyridinium chloride, 1-Methyl-1-octylpyrrolidinium Cationic surfactants such as muchloride; decanoic acid, stearic acid, 1-dodecanesulfonic acid anionic surfactants such as dodecylbenzenesulfonic acid and lauryl phosphate; Dodecylaminoacetic acid betaine, dodecylaminomethyl dimethylsulfopropyl betaine, coca Amphoteric surfactants such as amphoteric betaine and amidopropyl betaine are also included. They may be used alone or in combination of two or more.

[0042] When the solution containing component (B) contains a surfactant, the content of the surfactant is In 100% by mass of the solution containing the amine, the amount is preferably 5% by mass or less, more preferably 3% by mass or less, It is more preferable that the amount of the water is 10% or less.

[0043] The solution containing component (B) contains a water-miscible solvent, which makes it possible to dissolve hydrophobic substances that are not miscible with water in water. It has the effect of blending with

[0044] Examples of water-miscible solvents include isopropanol, ethylene glycol, and propylene. Glycol, methanol, ethanol, propanol, butanol, glycerol, 2- (2-aminoethoxyethanol) and other polar protic solvents; acetone, dimethylsulfate oxide, N,N-dimethylformamide, N-methylpyrrolidone, acetonitrile, etc. aprotic solvents; non-polar solvents such as hexane, benzene, toluene, diethyl ether, etc. These water-miscible solvents may be used alone or in combination of two or more. You may do so.

[0045] When the solution containing component (B) contains a surfactant, the content of the water-miscible solvent is In 100% by mass of the solution containing It is more preferably equal to or less than mass %.

[0046] The pH of the solution containing component (B) is preferably 8 to 14 because this has excellent solubility for silicon. It is preferable that the number of carbon atoms is 9 to 14, and more preferable that the number of carbon atoms is 10 to 14.

[0047] The method for producing the solution containing component (B) is not particularly limited. It can be produced by mixing it with other ingredients. The order of mixing is not particularly limited. All the components may be mixed at once, or some of the components may be mixed at once. The remaining ingredients may be premixed and then mixed.

[0048] As a method for contacting a structure containing silicon having an oxidized surface with a solution containing component (B), For example, a structure containing silicon whose surface is oxidized is immersed in a solution containing component (B). The method comprises spin-coating a solution containing component (B) onto a silicon-containing structure having an oxidized surface. Among these methods, a method of forming a structure containing silicon with an oxidized surface is Since the contact between the surface of the silicon oxide and the solution containing component (B) is excellent, A method in which a structure containing the component (B) is immersed in a solution containing the component (B) is preferred.

[0049] The time for which the structure containing silicon with an oxidized surface is immersed in the solution containing component (B) is In view of the excellent solubility of the recombinant, 0.5 minutes or more is preferable, and 1 minute or more is more preferable. The time for which the structure containing silicon with an oxidized surface is immersed in the solution containing component (B) is This is because it has excellent selective solubility of the 110 face of silicon crystals relative to the 100 face of silicon crystals. , 30 minutes or less is preferable, and 10 minutes or less is more preferable.

[0050] The temperature at which the structure containing silicon with an oxidized surface is immersed in the solution containing component (B) is In order to obtain excellent solubility of silicon, a temperature of 15° C. or higher is preferable, and a temperature of 20° C. or higher is more preferable. stomach. The temperature at which the structure containing silicon with an oxidized surface is immersed in the solution containing component (B) is , and has excellent selective solubility of the 110 face of silicon crystal relative to the 100 face of silicon crystal. Therefore, the temperature is preferably 100° C. or lower, and more preferably 80° C. or lower. The temperature when the structure containing silicon having an oxidized surface is immersed in a solution containing component (B) and corresponds to the temperature of the solution containing component (B) at the time of immersion.

[0051] The method of immersing a structure containing silicon with an oxidized surface in a solution containing component (B) is described in The type of processing may be, for example, a batch type, a single wafer type, etc.

[0052] Etching rate of the 110 plane of a silicon crystal when immersed in a solution containing component (B) ER 110 Since the efficiency of forming nano-shapes in the horizontal direction is excellent, a rate of 1 nm / min or more is preferred. The rate is preferably 3 nm / min or more, and more preferably 5 nm / min or more.

[0053] Etching rate for 100 faces of silicon crystal when immersed in a solution containing component (B) ER 100Since the efficiency of forming nano-shapes in the horizontal direction is excellent, a speed of 40 nm / min or less is preferable. It is preferably 30 nm / min or less, more preferably 20 nm / min or less.

[0054] The number of silicon crystals per 100 faces when immersed in a solution containing component (B) Selective dissolution of 110 surface (ER 110 / ER 100 ) is the horizontal dissolution of silicon crystals In view of excellent processability, it is preferably greater than 1, more preferably from 1.1 to 10, and even more preferably from 1.2 to 7. It is preferably from 1.3 to 5.

[0055] In this specification, the etching rate and selective solubility are determined by the method described in the Examples below. Measured at.

[0056] (Application) The etching method of the present invention is a method for etching a silicon crystal with a 110 plane relative to a 100 plane. Since it has excellent selective solubility of silicon, it is suitable as an etching method for dissolving silicon. an etching method in which the 110th face of a silicon crystal is dissolved relative to the 100th face of a silicon crystal; This is particularly suitable. Therefore, the etching method of the present invention is suitable for etching a semiconductor device having a silicon-containing structure. The present invention is suitable for etching a vertical transistor having a structure including silicon, a silicon It is more suitable for a gate-all-around type transistor having a structure including silicon. It is particularly suitable for vertical transistors having structures including cones. EXAMPLES

[0057] The present invention will be described in more detail below using examples. Unless otherwise stated, the following examples are not intended to be limiting.

[0058] (Preferential solubility of the 110 face of a silicon crystal relative to the 100 face of a silicon crystal) The thickness of the silicon substrate before and after immersion in potassium hydroxide solution. The film thickness of the silicon substrate was measured using a spectroscopic interference type film thickness meter, and the silicon The selective solubility of the 110 face of a silicon crystal relative to the 100 face of a silicon crystal was calculated. ER 110 [nm / min] = (thickness of silicon substrate before immersion [nm] - thickness of silicon substrate after immersion (film thickness of silicon substrate [nm]) ÷ (immersion time [min]) (1) ER 100 [nm / min] = (thickness of silicon substrate before immersion [nm] - thickness of silicon substrate after immersion (film thickness of silicon substrate [nm]) ÷ (immersion time [min]) (2) Selective solubility = ER 110 [nm / min]÷ER 100 [nm / min] (3)

[0059] [Example 1] A silicon substrate with silicon crystals with 110 and 100 plane orientations was placed in a 0.5 mass% fluoride After immersing in the hydrochloric acid solution for 3 minutes, the silicon substrate was rinsed with ultrapure water. After masking, the sample was immersed in a 1% by mass aqueous solution of hydrogen peroxide at 50°C for 5 minutes. The silicon substrate was immersed in a 0.56% by mass aqueous solution of potassium hydroxide at 50°C for 3 minutes. I did. The etching evaluation results are shown in Table 1.

[0060] [Example 2] The same procedure as in Example 1 was carried out except that the concentration of the aqueous hydrogen peroxide solution was changed to 10% by mass. The etching evaluation results are shown in Table 1.

[0061] [Comparative Example 1] A silicon substrate with silicon crystals with 110 and 100 plane orientations was placed in a 0.5 mass% fluoride After immersing in the hydrochloric acid solution for 3 minutes, the silicon substrate was rinsed with ultrapure water. After masking, the specimen was immersed in a 0.56% by mass potassium hydroxide aqueous solution at 50°C for 5 minutes. . The etching evaluation results are shown in Table 1.

[0062] [Table 1]

[0063] As can be seen from Table 1, the etching method of the embodiment has a 100-plane of the silicon crystal. The selective dissolution of the 110 plane of the silicon crystal was remarkably excellent. On the other hand, the etching method of the comparative example has a 100-plane ratio of the silicon crystal. The selective dissolution of the 10th surface was poor. [Industrial Applicability]

[0064] The etching method of the present invention is a method for etching a silicon crystal with a 110 plane relative to a 100 plane. Since it has excellent selective solubility of silicon, it is suitable as an etching method for dissolving silicon. an etching method in which the 110th face of a silicon crystal is dissolved relative to the 100th face of a silicon crystal; This is particularly suitable. Therefore, the etching method of the present invention is suitable for etching a semiconductor device having a silicon-containing structure. The present invention is suitable for etching a vertical transistor having a structure including silicon, a silicon It is more suitable for a gate-all-around type transistor having a structure including silicon. It is particularly suitable for vertical transistors having structures including cones.

Claims

1. An etching method comprising the following steps (1) and (2) in sequence: Step (1): Oxidizing the surface of a silicon-containing structure Step (2): Etching the structure containing silicon whose surface has been oxidized

2. The oxidation method in the step (1) comprises oxidizing a silicon-containing structure by dissolving the silicon-containing structure in a solution containing an oxidizing agent (A). The etching method according to claim 1 , wherein the etching is carried out by contacting the

3. The oxidizing agent (A) is hydrogen peroxide, peroxodisulfuric acid, a salt of peroxodisulfuric acid, chromic acid, and 3. The composition according to claim 2, comprising at least one compound selected from the group consisting of salts of chromate and chromic acid. Etching method.

4. The etching method of claim 2 , wherein the oxidizing agent (A) comprises hydrogen peroxide.

5. The etching method according to claim 2 , wherein the solution containing the oxidizing agent (A) contains water.

6. The content of the oxidizing agent (A) in 100% by mass of the solution containing the oxidizing agent (A) is 0.1% by mass to 3 3. The etching method according to claim 2, wherein the content of the oxygen-containing gas is 0 mass %.

7. The etching method in the step (2) is to oxidize the surface of the silicon-containing structure by etching. The etching method according to claim 1, wherein the etching is carried out by contacting the substrate with a solution containing an alkaline compound (B). method.

8. The alkaline compound (B) is a quaternary ammonium hydroxide compound, potassium hydroxide, and hydroxide The composition according to claim 7, further comprising at least one compound selected from the group consisting of calcium phosphate and calcium fluoride. Etching method.

9. 8. The method of claim 7, wherein the alkaline compound (B) comprises a quaternary ammonium hydroxide compound. Etching method.

10. The etching method according to claim 7 , wherein the solution containing the alkaline compound (B) contains water.

11. Content of alkaline compound (B) in 100% by mass of a solution containing alkaline compound (B) The etching method according to claim 7, wherein the content of the oxygen in the oxygen-containing solution is 0.01% by mass to 30% by mass.

12. 2. The method according to claim 1, wherein the 110 face of the silicon crystal is melted relative to the 100 face of the silicon crystal. Etching method.

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

14. A method for manufacturing a semiconductor device, comprising the etching method according to any one of claims 1 to 13. method.

15. A method for producing a vertical transistor comprising the etching method according to any one of claims 1 to 13. Manufacturing method.

16. A gate-all-around etching method comprising the etching method according to any one of claims 1 to 13. A method for manufacturing a gate type transistor.

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