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

Abstract

To provide: an etching composition which suppresses the dissolution of silicon, promotes the dissolution of silicon germanium, and has excellent selective dissolubility of silicon germanium to silicon; and an etching method, a method for manufacturing a semiconductor device, and a method for manufacturing a gate-all-around transistor, in which the etching composition is used.SOLUTION: There is provided an etching composition containing an oxidant (A) and an organic acid (B) and selectively dissolving silicon germanium in silicon. The oxidant (A) contains nitric acid, and the percentage content of the organic acid (B) is 50 mass% or more relative to 100 mass% of the etching composition. There is also provided an etching method for etching a structure containing silicon and silicon germanium using the etching composition.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an etching composition, an etching method, a method for manufacturing a semiconductor device, and a method for manufacturing a gate-all-around transistor. [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, studies have been conducted to improve performance by changing the structure, such as with fin transistors (fin FETs) and gate-all-around transistors (GAA FETs), as well as to promote further miniaturization and integration.

[0003] In FinFETs, by forming fins perpendicular to the silicon substrate, not only does it increase the number of transistors per unit area, but it also exhibits excellent performance in ON / OFF control at low voltages. However, in order to further improve performance, it is necessary to devise measures such as increasing the aspect ratio of the fins, but if the aspect ratio is too large, there are issues such as the fins collapsing during the cleaning and drying processes used to form the fins.

[0004] On the other hand, in GAA FETs, the nanosheet or nanowire that forms the channel is covered with a gate electrode, increasing the contact area between the channel and gate electrode, thereby improving the transistor performance per unit area.

[0005] To form a GAA FET, an etching composition is required to selectively etch silicon germanium from a structure in which silicon and silicon germanium are alternately stacked. As such an etching composition, Patent Document 1 discloses a composition containing acetic acid. Patent Document 2 discloses a composition containing hydrogen peroxide. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-303305 [Patent Document 2] Japanese Patent Application Publication No. 2019-050365 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the etching composition disclosed in Patent Document 1 has a low content of acetic acid, and the selective solubility of silicon germanium relative to silicon is not sufficient. Furthermore, the etching composition containing hydrogen peroxide disclosed in Patent Document 2 also does not have sufficient selective solubility of silicon germanium relative to silicon.

[0008] As in Patent Documents 1 and 2, etching compositions containing various components have been investigated in the past, but none of them can be said to have sufficient selective solubility of silicon germanium relative to silicon.

[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 that suppresses dissolution of silicon, promotes dissolution of silicon germanium, and exhibits excellent selective solubility of silicon germanium relative to silicon. Another object of the present invention is to provide an etching method using the etching composition, a method for manufacturing a semiconductor device, and a method for manufacturing a gate-all-around transistor. [Means for solving the problem]

[0010] As a result of extensive research, the present inventors have found that the etching composition of the present invention described below inhibits the dissolution of silicon, promotes the dissolution of silicon germanium, and has excellent selective solubility of silicon germanium relative to silicon.

[0011] That is, the gist of the present invention is as follows. [1] An etching composition that selectively dissolves silicon germanium relative to silicon, comprising an oxidizing agent (A) and an organic acid (B), wherein the oxidizing agent (A) comprises nitric acid, and the content of the organic acid (B) is 50 mass% or more relative to 100 mass% of the etching composition. [2] The etching composition according to [1], wherein the organic acid (B) contains at least one compound selected from the group consisting of acetic acid, propionic acid, oxalic acid, and citric acid. [3] The etching composition according to [1] or [2], further comprising a fluorine-containing compound (C). [4] The etching composition according to [3], wherein the fluorine-containing compound (C) comprises at least one compound selected from the group consisting of hydrofluoric acid, ammonium fluoride, and hexafluorosilicic acid. [5] The etching composition according to [3] or [4], wherein the content of the fluorine-containing compound (C) is 5 mass % or less in 100 mass % of the etching composition. [6] The etching composition according to any one of [1] to [5], further comprising water (D). [7] The etching composition according to [6], wherein the content of water (D) is 20 mass % or less in 100 mass % of the etching composition. [8] An etching method, comprising etching a structure containing silicon and silicon germanium using the etching composition according to any one of [1] to [7]. [9] A method for manufacturing a semiconductor device, comprising the step of etching a structure containing silicon and silicon germanium using the etching composition according to any one of [1] to [7].

[10] A method for manufacturing a gate-all-around transistor, comprising the step of etching a structure containing silicon and silicon germanium using the etching composition according to any one of [1] to [7]. [Effects of the Invention]

[0012] The etching composition of the present invention inhibits the dissolution of silicon, promotes the dissolution of silicon germanium, and has excellent selective solubility of silicon germanium relative to silicon. Furthermore, the etching method of the present invention, the method for manufacturing a semiconductor device of the present invention, and the method for manufacturing a gate-all-around transistor of the present invention, which use such an etching composition of the present invention, suppress the dissolution of silicon and promote the dissolution of silicon germanium in the etching step, and due to the excellent selective solubility of silicon germanium relative to silicon, can perform highly accurate etching and manufacture desired products with a high yield. DETAILED DESCRIPTION OF THE INVENTION

[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 the expression "to" is used, it is used as an expression including the numerical values ​​or physical property values ​​before and after it.

[0014] The etching composition of the present invention contains an oxidizing agent (A) (hereinafter may be referred to as "component (A)") and an organic acid (B) (hereinafter may be referred to as "component (B)"), and the oxidizing agent (A) contains nitric acid, and the content of the organic acid (B) is 50 mass% or more in 100 mass% of the etching composition, so that silicon germanium can be selectively dissolved relative to silicon.

[0015] <Component (A)> Component (A) is an oxidizing agent. When the etching composition contains an oxidizing agent, it exhibits the effect of oxidizing the surface of silicon or silicon germanium.

[0016] Examples of oxidizing agents include nitric acid, hydrogen peroxide, permanganic acid, periodic acid, and perchloric acid. These oxidizing agents may be used alone or in combination of two or more. Among these oxidizing agents, nitric acid and hydrogen peroxide are preferred because they can remove metal components that are sources of contamination, and nitric acid is more preferred because it has excellent selective oxidation properties for silicon germanium. Therefore, the etching composition of the present invention is characterized by containing at least nitric acid as the oxidizing agent of component (A).

[0017] The content of component (A) is preferably 5% by mass or more, and more preferably 10% by mass or more, in 100% by mass of the etching composition, because it has excellent selective oxidation properties for silicon germanium. The content of component (A) is preferably 50% by mass or less, and more preferably 40% by mass or less, in 100% by mass of the etching composition, because this provides excellent suppression of silicon etching.

[0018] When an oxidizing agent other than nitric acid is used in combination as component (A), the content of nitric acid in 100% by mass of component (A) is preferably 50% by mass or more, and more preferably 80 to 100% by mass, from the viewpoint of effectively obtaining the effect of selectively oxidizing silicon and germanium by using nitric acid.

[0019] <Ingredient (B)> Component (B) is an organic acid. By including an organic acid in the etching composition, the effect of protecting silicon and oxide films is exhibited.

[0020] Examples of organic acids include acetic acid, propionic acid, oxalic acid, and citric acid. These organic acids may be used alone or in combination of two or more. Among these organic acids, acetic acid, propionic acid, oxalic acid, and citric acid are preferred, and acetic acid is more preferred, because they are excellent at inhibiting silicon etching.

[0021] The content of component (B) is 50% by mass or more, preferably 55% by mass or more, and more preferably 60% by mass or more, based on 100% by mass of the etching composition, because it has excellent silicon etching suppression properties and excellent penetration into narrow spaces. The content of component (B) is preferably 95 mass % or less, more preferably 90 mass % or less, and even more preferably 75 mass % or less, based on 100 mass % of the etching composition, because it has excellent selective oxidation properties for silicon germanium.

[0022] <Component (C)> The etching composition of the present invention preferably contains a fluorine-containing compound (C) (hereinafter sometimes referred to as "component (C)") in addition to the component (A) and the component (B).

[0023] When the etching composition contains the fluorine-containing compound as component (C), it exhibits the effect of etching the surface of oxidized silicon or silicon germanium.

[0024] Examples of fluorine-containing compounds include hydrofluoric acid, ammonium fluoride, and hexafluorosilicic acid. These fluorine-containing compounds may be used alone or in combination of two or more. Among these fluorine-containing compounds, hydrofluoric acid, ammonium fluoride, and hexafluorosilicic acid are preferred, and hydrofluoric acid is more preferred, because they have excellent selective solubility for silicon germanium.

[0025] The content of component (C) is preferably 0.01% by mass or more, and more preferably 0.1% by mass or more, in 100% by mass of the etching composition, because it provides excellent solubility for silicon germanium. From the viewpoint of reducing damage to silicon, the content of component (C) is preferably 5% by mass or less, and more preferably 3% by mass or less, in 100% by mass of the etching composition.

[0026] <Ingredient (D)> The etching composition of the present invention preferably contains water (D) (hereinafter sometimes referred to as "component (D)") in addition to component (A), component (B), and component (C).

[0027] When the etching composition contains water as component (D), it exhibits the effect of inhibiting etching of silicon.

[0028] The content of component (D) is preferably 5% by mass or more, and more preferably 10% by mass or more, in 100% by mass of the etching composition, because this facilitates the production of the etching composition. The content of component (D) is preferably 30% by mass or less, and more preferably 20% by mass or less, in 100% by mass of the etching composition, because this can improve the etch rate.

[0029] <Other ingredients> The etching composition of the present invention may contain other components in addition to the component (A), the component (B), the component (C), and the component (D).

[0030] <Mass ratio of each component> The mass ratio of component (B) to 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 1 to 10, more preferably 2 to 5, because this provides an excellent balance between the effect of oxidizing the surface of silicon or silicon germanium and the effect of protecting silicon or an oxide film.

[0031] The mass ratio of component (C) to component (A) in the etching composition of the present invention (mass of component (C) / mass of component (A), hereinafter referred to as "(C) / (A)") is preferably 0.005 to 0.1, and more preferably 0.01 to 0.05, because this provides an excellent balance between the effect of oxidizing the surface of silicon or silicon germanium and the effect of etching the surface of oxidized silicon or silicon germanium.

[0032] The mass ratio of component (C) to component (B) in the etching composition of the present invention (mass of component (C) / mass of component (B), hereinafter referred to as "(C) / (B)") is preferably 0.001 to 0.05, and more preferably 0.002 to 0.025, because this provides an excellent balance between the effect of protecting silicon or an oxide film and the effect of etching the surface of oxidized silicon or silicon germanium.

[0033] <Method of manufacturing etching composition> The method for producing the etching composition of the present invention is not particularly limited, and the composition can be produced by mixing component (A) and component (B), and, if necessary, component (C), component (D), 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.

[0034] <Physical properties of etching composition> The silicon etch rate ER of the etching composition of the present invention Si Since the selective solubility of silicon germanium relative to silicon is excellent, the rate is preferably 1.0 nm / min or less, more preferably 0.5 nm / min or less, and even more preferably 0.3 nm / min or less.

[0035] The silicon germanium etch rate ER of the etching composition of the present invention SiGe Since the selective solubility of silicon germanium relative to silicon is excellent, the rate is preferably 0.5 nm / min or more, more preferably 1.0 nm / min or more, and even more preferably 2.0 nm / min or more.

[0036] The dissolution selectivity DSR (ER) of the etching composition of the present invention between silicon and silicon germanium SiGe / ER Si ) is preferably 10 or more, more preferably 15 or more, because this provides excellent selective solubility of silicon germanium relative to silicon.

[0037] Since silicon oxide may be exposed in a structure containing silicon and silicon germanium, it is preferable to suppress dissolution of the silicon oxide. The silicon oxide etch rate ER of the etching composition of the present invention SiOx is preferably 50 nm / min or less, more preferably 40 nm / min or less, and even more preferably 30 nm / min or less.

[0038] In addition, the etch rate ER Si , etch rate ER SiGe , dissolution selectivity ratio DSR, etch rate ER SiOx is measured and calculated by the method described in the Examples section below.

[0039] <Target to be etched by etching composition> The etching composition of the present invention suppresses dissolution of silicon, promotes dissolution of silicon germanium, and has excellent selective solubility of silicon germanium relative to silicon. 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 in which silicon and silicon germanium are alternately stacked, which are necessary for forming a GAA type FET.

[0040] 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, in order to be suitable for etching with the etching composition of the present invention. On the other hand, the silicon content in silicon germanium is preferably 95 mass % or less, more preferably 85 mass % or less, based on 100 mass % of silicon germanium, in order to be suitable for etching with the etching composition of the present invention. Furthermore, the content of germanium in silicon germanium is preferably 5 mass % or more, more preferably 15 mass % or more, based on 100 mass % of silicon germanium, in order to be suitable for etching with the etching composition of the present invention. On the other hand, the germanium content in silicon germanium is preferably 90 mass % or less, more preferably 80 mass % or less, based on 100 mass % of silicon germanium, in order to be suitable for etching with the etching composition of the present invention.

[0041] The silicon germanium alloy film may be produced by deposition using a known method, but is preferably produced by deposition using a crystal growth method, since this provides excellent mobility of electrons and holes after the transistor is formed.

[0042] In a structure containing silicon and silicon germanium or a structure in which silicon and silicon germanium are alternately stacked, silicon oxide may be exposed.

[0043] <Etching method> The etching method of the present invention is a method for etching a structure containing silicon and silicon germanium using the etching composition of the present invention.

[0044] The etching method may be a known method, such as a batch method or a single wafer method.

[0045] The temperature during etching is preferably 15° C. or higher, more preferably 20° C. or higher, since this can improve the etching rate. The temperature during etching is preferably 100° C. or less, more preferably 80° C. or less, from the viewpoint 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.

[0046] <Application> The etching composition and etching method of 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. Since the etching composition and etching method of the present invention suppress the dissolution of silicon, promote the dissolution of silicon germanium, and have excellent selective solubility of silicon germanium relative to silicon, they can be particularly suitably used in the manufacture of GAA-type FETs, which includes a step of etching a structure containing silicon and silicon germanium. [Example]

[0047] 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.

[0048] <Raw materials> In the following examples and comparative examples, the following materials were used as raw materials for producing the etching compositions. Ingredient (A-1): Nitric acid Ingredient (A'-1): Hydrogen peroxide Ingredient (B-1): Acetic acid Component (C-1): Hydrofluoric acid Ingredient (D-1): Water

[0049] <Method for measuring silicon etch rate> A silicon substrate cut to 7 cm x 7 cm and having a thickness of approximately 0.7 mm was immersed in the etching compositions obtained in the Examples and Comparative Examples at 25°C for 60 minutes or more, and the mass of the silicon substrate was measured using a balance before and after immersion. From the change in mass, the silicon etch rate ER was calculated using the following formula (1). Si [nm / min] was calculated. ER Si [nm / min] = change in mass of silicon substrate ÷ (density of silicon substrate × surface area of ​​silicon substrate × immersion time of silicon substrate) (1)

[0050] <Method for measuring the etch rate of silicon germanium> A silicon substrate having a silicon germanium alloy film (50 nm thick) with a germanium content of 25 mass % formed on its surface was immersed in the etching compositions obtained in the Examples and Comparative Examples at 25°C, and the change in film thickness was measured using a spectroscopic ellipsometer (model name "UVISEL ER", manufactured by Horiba, Ltd.). The etch rate ER of silicon germanium was calculated using the following formula (2). SiGe [nm / min] was calculated. ER SiGe [nm / min] = change in thickness of silicon germanium alloy film ÷ immersion time of silicon substrate (2)

[0051] <Dissolution selectivity between silicon and silicon germanium> The dissolution selectivity ratio DSR of silicon and silicon germanium was calculated using the following formula (3). DSR=ER SiGe [nm / min]÷ER Si [nm / min] (3)

[0052] <Method for measuring silicon oxide etch rate> A silicon substrate having a silicon oxide film (280 nm thick) formed on its surface was immersed in the etching compositions obtained in the Examples and Comparative Examples at 25°C, and the change in film thickness was measured using a reflectance spectroscopic film thickness meter (model name "FE-3000", manufactured by Otsuka Electronics Co., Ltd.). The etch rate ER of silicon oxide was calculated using the following formula (4). SiOx [nm / min] was calculated. ER SiOx [nm / min] = change in thickness of silicon oxide film ÷ immersion time of silicon substrate (4)

[0053] [Example 1] The etching composition was obtained by mixing the components so that, based on 100 mass% of the etching composition, component (A-1) was 21.0 mass%, component (B-1) was 62.5 mass%, component (C-1) was 1.0 mass%, and component (D-1) was 15.5 mass%. The evaluation results of the obtained etching compositions are shown in Table 1.

[0054] [Examples 2 to 4, Comparative Examples 1 to 3] The same procedure as in Example 1 was carried out except that the types and contents of the raw materials were as shown in Table 1, to obtain etching compositions. The evaluation results of the obtained etching compositions are shown in Table 1.

[0055] [Table 1]

[0056] As can be seen from Table 1, the etching compositions obtained in Examples 1 to 4 suppress the dissolution of silicon, promote the dissolution of silicon germanium, and are excellent in the selective solubility of silicon germanium relative to silicon.

[0057] The etching composition obtained in Comparative Example 1, which contained less component (B) and more component (D), suppressed the dissolution of silicon, but also suppressed the dissolution of silicon germanium, resulting in poor selective solubility of silicon germanium relative to silicon.

[0058] The etching composition obtained in Comparative Example 2, which contained less component (B) and more component (A), promoted the dissolution of silicon germanium, but also promoted the dissolution of silicon, resulting in poor selective solubility of silicon germanium relative to silicon.

[0059] The etching composition obtained in Comparative Example 3, which used hydrogen peroxide as component (A), inhibited the dissolution of silicon to some extent and promoted the dissolution of silicon germanium to some extent, but was inferior in the selective solubility of silicon germanium relative to silicon. [Industrial Applicability]

[0060] The etching composition of the present invention and the etching method of the present invention using this etching composition suppress the dissolution of silicon, promote the dissolution of silicon germanium, and exhibit excellent selective solubility of silicon germanium relative to silicon, and therefore can be suitably used in the production of semiconductor devices, and in particular, in the production of GAA type FETs.

Claims

1. An etching composition that selectively dissolves silicon germanium relative to silicon, the etching composition comprising an oxidizing agent (A) and an organic acid (B), wherein the oxidizing agent (A) contains nitric acid, and the content of the organic acid (B) is 50 mass% or more relative to 100 mass% of the etching composition; An etching composition, wherein the content of the oxidizing agent (A) is 21 mass% or more in 100 mass% of the etching composition.

2. 2. The etching composition according to claim 1, wherein the organic acid (B) comprises at least one compound selected from the group consisting of acetic acid, propionic acid, oxalic acid, and citric acid.

3. The etching composition according to claim 1 or 2, further comprising a fluorine-containing compound (C).

4. 4. The etching composition according to claim 3, wherein the fluorine-containing compound (C) comprises at least one compound selected from the group consisting of hydrofluoric acid, ammonium fluoride, and hexafluorosilicic acid.

5. The etching composition according to claim 3 or 4, wherein the content of the fluorine-containing compound (C) is 5 mass% or less in 100 mass% of the etching composition.

6. The etching composition according to any one of claims 1 to 5, further comprising water (D).

7. The etching composition according to claim 6, wherein the content of water (D) is 20 mass% or less in 100 mass% of the etching composition.

8. An etching method for etching a structure containing silicon and silicon germanium using the etching composition according to any one of claims 1 to 7.

9. A method for manufacturing a semiconductor device, comprising the step of etching a structure containing silicon and silicon germanium using the etching composition according to any one of claims 1 to 7.

10. A method for manufacturing a gate-all-around transistor, comprising the step of etching a structure containing silicon and silicon germanium using the etching composition according to any one of claims 1 to 7.

Images