Etching composition, etching method, and method for manufacturing a semiconductor substrate

Abstract

The present invention provides an etching composition, an etching method, and a semiconductor substrate manufacturing method that exhibit excellent selectivity for SiGe and suppression of damage to Si, as well as excellent defoaming properties. [Solution] The present invention provides an etching composition, an etching method, and a method for manufacturing a semiconductor substrate, each containing (A) an oxidizing agent, (B) a compound or salt thereof capable of releasing fluoride ions, and (C) a nonionic surfactant comprising at least one selected from the group consisting of a compound having a specific structure (c1) and a compound having a specific structure (c2).

Description

[Technical Field]

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

[0002] In recent years, semiconductor manufacturing processes have seen advancements in wiring miniaturization and high-layer stacking. Silicon germanium alloy (SiGe, hereafter sometimes simply referred to as "silicon germanium") is used in manufacturing processes involving such miniaturization and high-layer stacking. SiGe is made by adding germanium to silicon, and compared to pure silicon, it has advantages such as high conductivity, low power consumption, and low noise generation.

[0003] For example, in the manufacturing of LSIs and the like, a SiGe layer is used as a buffer layer when introducing a strained SOI (Si on Insulator) structure. More specifically, a method is employed in which a SiGe layer with a high germanium concentration is stacked on a silicon substrate as a sacrificial film, and then a SiGe layer with a low germanium concentration is further stacked on top of that.

[0004] As an etching solution used for etching such laminates, for example, Patent Document 1 describes a silicon-containing layer, particularly α-Si, SiO x A composition for selectively etching a silicon germanium alloy (SiGe) layer in the presence of a layer made of SiON, SiN, or a combination thereof is disclosed, comprising (a) an oxidizing agent, (b) an acid selected from inorganic and organic acids, (c) an etching solution containing a fluoride ion source, (d) polyvinylpyrrolidone (PVP), and (e) water. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2021 / 004759 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, there is still room for improvement regarding the etching process in the semiconductor manufacturing process using SiGe, as described above.

[0007] Firstly, when etching a laminate, as described above, in which a SiGe layer with a high germanium concentration is laminated as a sacrificial film on a silicon substrate, and a SiGe layer with a low germanium concentration is further laminated on top of it, it is required that the SiGe layer with the high germanium concentration be etched while the other SiGe layers are not damaged (SiGe selectivity). In addition, it is required that the silicon layer (silicon substrate, etc.) is not damaged (suppression of damage to Si). However, conventional etching solutions do not have sufficient SiGe selectivity or suppression of damage to the silicon layer.

[0008] Secondly, conventional etching solutions have room for improvement in terms of their defoaming properties. In the actual manufacturing process, etching is performed in an etching apparatus connected to a tank that stores the etching solution. The etching solution used in the etching process is sent to the tank from a drain connected to the etching apparatus, and the used etching solution is refilled into the tank, thus circulating the etching solution. Furthermore, for safety management during operation, the tank is equipped with a water level detection unit such as a water level gauge or tank gauge, and if the water level of the etching solution exceeds a standard value during operation, the water level detection unit will detect this and stop the operation.

[0009] When circulating the etching solution as described above, or during operation, if bubbles are generated in the etching solution, the apparent water level may become higher than the actual water level. This can cause the water level detection unit to falsely detect that the water level has exceeded the standard level even though it has not. As a result, the etching equipment will be shut down, and production efficiency will decrease.

[0010] This invention has been made in view of the above-mentioned circumstances, and aims to provide an etching composition, an etching method, and a method for manufacturing a semiconductor substrate that are excellent in selectivity for SiGe and suppression of damage to Si, as well as excellent in defoaming. [Means for solving the problem]

[0011] As a result of diligent research to achieve the above-mentioned objectives, the present inventors have found that an etching composition contains (A) an oxidizing agent, (B) a compound or salt thereof capable of releasing fluoride ions, and (C) a nonionic surfactant comprising at least one selected from the group consisting of a compound having a specific structure (c1) and a compound having a specific structure (c2), and have completed the present invention.

[0012] In other words, the present invention is as follows. <1> The etching composition contains (A) an oxidizing agent, (B) a compound or salt thereof capable of releasing fluoride ions, and (C) a nonionic surfactant selected from the group consisting of a compound (c1) represented by the following general formula (c1) and a compound (c2) represented by the following general formula (c2).

[0013] [ka]

[0014] (In the general formula (c1), x, y, and n represent numbers greater than or equal to 1.)

[0015] [ka]

[0016] (In general formula (c2), A is a divalent group containing the structural unit (c2-1) represented by the following formula (c2-1) and the structural unit (c2-2) represented by the following formula (c2-2), and z represents a number of 1 or more.)

[0017] [Chemistry]

[0018] <2> The component (A) is the etching composition according to <1>, which contains at least one selected from the group consisting of hydrogen peroxide and oxoacids. <3> The component (B) is the etching composition according to <1> or <2>, which is at least one selected from the group consisting of hydrogen fluoride, ammonium fluoride, ammonium bifluoride, triethanolammonium fluoride, diglycolammonium fluoride, methyldiethanolammonium fluoride, tetramethylammonium fluoride, triethylamine trihydrofluoride, fluoroboric acid, tetrafluoroboric acid, ammonium tetrafluoroborate, fluoroacetic acid, ammonium fluoroacetate, trifluoroacetic acid, silicofluoric acid, ammonium silicofluoride, and tetrabutylammonium tetrafluoroborate. <4> The content of the component (A) is 0.01 to 20% by mass, which is the etching composition according to <1> or <2>. <5> The content of the component (B) is 0.01 to 10% by mass, which is the etching composition according to <4>. <6> The content of the component (C) is 0.0001 to 3% by mass, which is the etching composition according to <1> or <2>. <7> The etching composition according to <1> or <2>, which further contains water. <8> The pH is 6 or less, which is the etching composition according to <7>. <9> The etching composition according to <1> or <2>, which is an etching composition for selectively etching a layer containing a silicon germanium alloy (SiGe). <10> An etching method comprising the step of etching a laminated substrate, which includes a substrate and a layer containing a silicon germanium alloy (SiGe) provided on the substrate, using an etching composition, wherein the etching composition contains (A) an oxidizing agent, (B) a compound or salt thereof capable of releasing fluoride ions, and (C) a nonionic surfactant selected from the group consisting of a compound (c1) represented by the following general formula (c1) and a compound (c2) represented by the following general formula (c2).

[0019] [ka]

[0020] (In the general formula (c1), x, y, and n represent numbers greater than or equal to 1.)

[0021] [ka]

[0022] (In general formula (c2), A is a divalent group containing the structural unit (c2-1) represented by the following formula (c2-1) and the structural unit (c2-2) represented by the following formula (c2-2), and z represents a number of 1 or more.)

[0023] [ka]

[0024] <11> A method for manufacturing a semiconductor substrate, comprising the steps of etching a laminated substrate, which includes a substrate and a layer containing a silicon germanium alloy (SiGe) provided on the substrate, using an etching composition, and cleaning the etched laminated substrate with a cleaning solution, wherein the etching composition contains (A) an oxidizing agent, (B) a compound or salt thereof capable of releasing fluoride ions, and (C) a nonionic surfactant selected from the group consisting of a compound (c1) represented by the following general formula (c1) and a compound (c2) represented by the following general formula (c2).

[0025] [ka]

[0026] (In the general formula (c1), x, y, and n represent numbers greater than or equal to 1.)

[0027] [ka]

[0028] (In general formula (c2), A is a divalent group containing the structural unit (c2-1) represented by the following formula (c2-1) and the structural unit (c2-2) represented by the following formula (c2-2), and z represents a number of 1 or more.)

[0029] [ka] [Effects of the Invention]

[0030] According to the present invention, it is possible to provide an etching composition, an etching method, and a method for manufacturing a semiconductor substrate that are excellent in selectivity for SiGe and suppression of damage to Si, as well as excellent in defoaming. [Modes for carrying out the invention]

[0031] The following describes in detail embodiments for carrying out the present invention (hereinafter simply referred to as "these embodiments"). These embodiments are illustrative for explaining the present invention and are not intended to limit the present invention to the following. The present invention can be appropriately modified and implemented within the scope of its gist. Furthermore, the configurations and parameters disclosed herein can be any combination unless otherwise specified. Moreover, the upper and lower limits of the values ​​disclosed herein can be any combination unless otherwise specified.

[0032] <Etching composition>

[0033] The etching composition according to this embodiment is an etching composition containing (A) an oxidizing agent, (B) a compound or salt thereof capable of releasing fluoride ions, and (C) a nonionic surfactant comprising at least one selected from the group consisting of a compound (c1) represented by the following general formula (c1) and a compound (c2) represented by the following general formula (c2).

[0034] [ka]

[0035] (In the general formula (c1), x, y, and n represent numbers greater than or equal to 1.)

[0036] [ka]

[0037] (In general formula (c2), A is a divalent group containing the structural unit (c2-1) represented by the following formula (c2-1) and the structural unit (c2-2) represented by the following formula (c2-2), and z represents a number of 1 or more.)

[0038] [ka]

[0039] The etching composition according to this embodiment exhibits excellent selectivity for SiGe and suppression of damage to Si, as well as excellent defoaming properties. Although the reason for this is not entirely clear, it is believed that by using a specific nonionic surfactant as component (C) in combination with component (A), which is an oxidizing agent, and component (B), which is a fluoride ion source, the selectivity between silicon germanium with different germanium concentrations can be improved (enhanced selectivity ratio), defoaming properties can be imparted, and furthermore, damage to Si can be suppressed (corrosion protection) can be maintained (the effects and benefits of this embodiment are not limited to these).

[0040] The etching composition according to this embodiment is not particularly limited to the etching target and can be used for various etching applications, but it is suitably used as an etching composition for selectively etching layers containing silicon germanium alloy (SiGe). Furthermore, the etching composition according to this embodiment is more suitable for etching laminated substrates having layers containing silicon germanium alloy (SiGe) and / or silicon (Si). Moreover, the etching composition according to this embodiment is more suitable for etching laminated substrates having layers containing silicon germanium alloy (SiGe) and silicon (Si). Furthermore, the etching composition according to this embodiment is even more suitable for etching laminated substrates having a first silicon germanium alloy (SiGe) layer, a second silicon germanium alloy (SiGe) layer, and a silicon (Si) layer, wherein the first silicon germanium alloy and the second silicon germanium alloy have different germanium content ratios. The etching composition according to this embodiment has the advantages of being excellent in at least SiGe selectivity and suppression of damage to Si, as well as excellent defoaming properties. These advantages of this embodiment can be effectively utilized in the etching of the laminated substrate described above.

[0041] The components and properties that can be contained in the etching composition according to this embodiment will be described below.

[0042] ((A) Oxidizing agent)

[0043] The etching composition according to this embodiment contains (A) an oxidizing agent. This allows the metal surface to be oxidized and etched. Preferably, the oxidizing agent is at least one selected from the group consisting of, for example, hydrogen peroxide and oxoacids.

[0044] Specific examples of using the etching composition according to this embodiment for etching will be described later, but a composition containing components other than component (A) may be prepared in advance, and component (A) may be mixed into the composition immediately before using the etching composition. For example, a first chemical solution containing components (B) and (C) may be prepared. Then, before etching (preferably immediately before), the above-mentioned first chemical solution and a second chemical solution containing component (A) may be mixed to prepare an etching solution before use. By adopting such a method of use, for example, the decomposition of the oxidizing agent over time can be effectively suppressed, and thus the etching effect can be expected to be further improved.

[0045] Furthermore, with respect to the etching composition according to this embodiment, if the first and second chemical solutions described above are prepared individually, it can be used as an etching kit comprising the first and second chemical solutions. Needless to say, the etching kit is not necessarily limited to two types of chemical solutions, and may also be an etching kit comprising other chemical solutions (for example, a third chemical solution, a fourth chemical solution, etc.) in addition to the first and second chemical solutions, depending on their components.

[0046] Specific examples of oxoacids include halogenated oxoacids (hypochlorous acid, chlorous acid, chloric acid, perchloric acid, hypobromous acid, bromous acid, bromate, perbromate, hypoiodic acid, iodic acid, iodic acid, periodic acid, etc.), boric acid (H3BO3, B(OH)3), silicic acid, nitric acid, nitrite (HNO2), etc. Furthermore, the etching composition according to this embodiment may also contain salts of these (for example, sodium salts, potassium salts, calcium salts, barium salts, ammonium salts, tetraalkylammonium salts, etc.).

[0047] Examples of halogenated oxoacids include hypochlorous acid, chlorous acid, chloric acid, perchloric acid, hypobromous acid, bromous acid, bromate, perbromate, hypoiodic acid, iodous acid, iodic acid, and periodic acid.

[0048] Among the above oxidizing agents, hydrogen peroxide and halogen oxoacids are preferred; at least one selected from the group consisting of hydrogen peroxide, hypoiodic acid, iodite acid, iodic acid (HIO3), and periodic acid is more preferred; and at least one selected from the group consisting of hydrogen peroxide, iodic acid, and periodic acid is even more preferred.

[0049] The etching composition according to this embodiment may use one of the above-mentioned oxidizing agents alone, or two or more may be used in combination.

[0050] The content of component (A) in the etching composition according to this embodiment is not particularly limited, but is preferably 0.01 to 20% by mass. The lower limit of this content is more preferably 0.05% by mass or more, even more preferably 0.08% by mass or more, and still more preferably 0.1% by mass or more. The upper limit of this content is more preferably 15% by mass or less, even more preferably 13% by mass or less, still more preferably 11% by mass or less, and still more preferably 10% by mass or less. When the content of component (A) is within the above range, the selectivity of SiGe, the suppression of damage to Si, and the defoaming properties can be further improved.

[0051] Furthermore, the etching composition according to this embodiment can achieve sufficient effects even without using oxidizing agents other than hydrogen peroxide, halogen oxoacids, boric acid, silicic acid, nitric acid, and nitrite as described above. From this viewpoint, the etching composition according to this embodiment does not need to contain oxidizing agents other than hydrogen peroxide, halogen oxoacids, boric acid, silicic acid, nitric acid, and nitrite. From a similar viewpoint, the etching composition according to this embodiment does not need to contain peracetic acid as a main component.

[0052] From a similar viewpoint, the etching composition according to this embodiment can achieve sufficient effects even without containing peracetic acid as the main component. From this viewpoint, the etching composition according to this embodiment preferably contains less than 0.1% by mass of peracetic acid, more preferably less than 0.05% by mass, even more preferably less than 0.001% by mass, and preferably does not contain peracetic acid at all.

[0053] From a similar viewpoint, the etching composition according to this embodiment preferably contains less than 0.1% by mass of hydroxylamine, more preferably less than 0.05% by mass, even more preferably less than 0.001% by mass, and preferably does not contain hydroxylamine.

[0054] From the above-mentioned viewpoint, it is more preferable that the etching composition according to this embodiment does not contain peracetic acid and hydroxylamine.

[0055] ((B) Compounds capable of releasing fluoride ions and salts thereof)

[0056] The etching composition according to this embodiment contains (B) a compound capable of releasing fluoride ions and its salts (hereinafter, these may be collectively referred to as "fluorinated compounds"). Specific examples of fluorinated compounds are not particularly limited, but it is preferable that they be at least one selected from the group consisting of hydrogen fluoride (HF), hexafluorosilicic acid, ammonium fluoride, ammonium hydrogen fluoride, triethanolammonium fluoride, diglycolammonium fluoride, methyldiethanolammonium fluoride, tetramethylammonium fluoride (TMAF), triethylamine trihydrofluoride, fluoroboric acid, tetrafluoroboric acid, ammonium tetrafluoroborate, fluoroacetic acid, ammonium fluoroacetate, trifluoroacetic acid, silicon fluoride, ammonium silicon fluoride, and tetrabutylammonium tetrafluoroborate. Among these, it is more preferable that it be at least one selected from the group consisting of hydrogen fluoride (HF), hexafluorosilicic acid, ammonium fluoride, ammonium hydrogen fluoride, and tetramethylammonium fluoride (TMAF), and even more preferable that it be at least one selected from the group consisting of hydrogen fluoride, ammonium fluoride, ammonium hydrogen fluoride, and tetramethylammonium fluoride (TMAF).

[0057] In the case of hydrogen fluoride, hydrofluoric acid (aqueous solution of hydrogen fluoride, hydrogen fluoride water, HF water) may be added when manufacturing the etching composition according to this embodiment. Furthermore, the salt of the compound capable of releasing fluoride ions is not particularly limited, but examples include sodium salts, potassium salts, ammonium salts, alkylammonium salts (e.g., tetramethylammonium salt, etc.).

[0058] (B) Component may be used alone or in combination of two or more components.

[0059] The content of component (B) in the etching composition according to this embodiment is not particularly limited, but is preferably 0.01 to 10% by mass. The lower limit of this content is more preferably 0.02% by mass or more, even more preferably 0.03% by mass or more, and still more preferably 0.04% by mass or more. The upper limit of this content is more preferably 5% by mass or less, even more preferably 3% by mass or less, still more preferably 1% by mass or less, and still more preferably 0.8% by mass or less. When the content of component (B) is within the above range, the selectivity of SiGe, the suppression of damage to Si, and the defoaming properties can be further improved.

[0060] Furthermore, the etching composition according to this embodiment can achieve sufficient effects even without containing compounds capable of releasing fluoride ions other than the above-mentioned hydrogen fluoride (HF), hexafluorosilicic acid, ammonium fluoride, ammonium hydrogen fluoride, and tetramethylammonium fluoride (TMAF).

[0061] ((C) Nonionic surfactant)

[0062] The etching composition according to this embodiment contains a nonionic surfactant selected from the group consisting of (C) a compound represented by general formula (c1) and a compound represented by general formula (c2).

[0063] [ka]

[0064] (In the general formula (c1), x, y, and n represent numbers greater than or equal to 1.)

[0065] In the general formula (c1), x+y is preferably between 7 and 17. The lower limit is more preferably 9 or greater, and even more preferably 11 or greater. The upper limit is more preferably 15 or less, and even more preferably 13 or less.

[0066] In general formula (c1), x is preferably between 1 and 16. The lower limit is more preferably 3 or greater, and even more preferably 4 or greater. The upper limit is more preferably 8 or less, and even more preferably 7 or less.

[0067] In general formula (c1), y is preferably between 1 and 16. The lower limit is more preferably 3 or greater, and even more preferably 4 or greater. The upper limit is more preferably 8 or less, and even more preferably 7 or less.

[0068] In general formula (c1), n ​​is preferably between 1 and 15. The lower limit is more preferably 5 or greater, and even more preferably 6 or greater. The upper limit is more preferably 13 or less, and even more preferably 11 or less.

[0069] Suitable specific examples of compound (c1) include, for example, commercially available products such as "Softanol 90," "TERGITOL TMN-10," "TERGITOL TMN-6," "Softanol 50," "Softanol 70," and "TERGITOL 15-S-5" (see the examples below for details).

[0070] [ka]

[0071] (In general formula (c2), A is a divalent group containing the structural unit (c2-1) represented by the following formula (c2-1) and the structural unit (c2-2) represented by the following formula (c2-2), and z represents a number of 1 or more.)

[0072] [ka]

[0073] In general formula (c2), A may be a divalent group containing the structural unit (c2-1) represented by formula (c2-1) and the structural unit (c2-2) represented by formula (c2-2), but it is preferable that it is composed only of structural unit (c2-1) and structural unit (c2-2).

[0074] In general formula (c2), z is preferably between 6 and 20. The lower limit is more preferably 8 or greater, and even more preferably 11 or greater. The upper limit is more preferably 18 or less, and even more preferably 15 or less.

[0075] Suitable specific examples of compound (c2) include commercially available products such as "P-PE61" and "Softanol EP9050" (see the examples below for details).

[0076] (C) Component may be used alone or in combination of two or more components.

[0077] The content of component (C) in the etching composition according to this embodiment is not particularly limited, but is preferably 0.0001 to 3% by mass. The lower limit of this content is more preferably 0.0003% by mass or more, and even more preferably 0.0005% by mass or more. The upper limit of this content is more preferably 2% by mass or less, even more preferably 1% by mass or less, even more preferably 0.9% by mass or less, and even more preferably 0.8% by mass or less. When the content of component (C) is within the above range, the selectivity of SiGe, the suppression of damage to Si, and the defoaming properties can be further improved.

[0078] The etching composition according to this embodiment may further contain components other than components (A), (B), and (C). Examples include accelerators, corrosion inhibitors, pH adjusters, buffers, other surfactants, solvents, etc., which will be described later.

[0079] (Promoting agent)

[0080] Examples of accelerators include components that can improve etching ability and accelerate etching. Preferably, the accelerator is a compound having two or more amino groups (NH2-), and more preferably an aliphatic compound having two or more amino groups (NH2-), or a cyclic compound having two or more amino groups (NH2-). By including such compounds as accelerators, the range of SiGe options can be further improved.

[0081] Specific examples of aliphatic compounds having two or more amino groups (NH2-) include alkyldiamines such as ethylenediamine, dialcylenetriamines such as diethylenetriamine, N-(2-aminoethyl)ethanolamine, and polyethylenepolyamine. Specific examples of cyclic compounds having two or more amino groups (NH2-) include cyclenes and cyclams.

[0082] The accelerator may be used alone or in combination of two or more types.

[0083] The content of the accelerator in the etching composition according to this embodiment is not particularly limited, but is preferably 0.01 to 3% by mass. The lower limit of this content is more preferably 0.03% by mass or more, even more preferably 0.05% by mass or more, and still more preferably 0.08% by mass or more. The upper limit of this content is more preferably 2% by mass or less, even more preferably 1% by mass or less, still more preferably 0.9% by mass or less, and still more preferably 0.8% by mass or less. When the accelerator content is within the above range, the selectivity of SiGe, the suppression of damage to Si, and the defoaming properties can be further improved.

[0084] (Corrosion inhibitor)

[0085] In the etching composition according to this embodiment, a corrosion inhibitor may be included as needed, taking into consideration the type of metal of the laminated substrate to be etched. The etching composition according to this embodiment is expected to achieve both corrosion prevention for metals other than SiGe, which is the target of etching, without reducing its effectiveness. Such corrosion inhibitors are not particularly limited, but include at least one selected from the group consisting of nitrogen-containing heterocyclic compounds, mercapto group-containing compounds, aliphatic amine compounds, zwitterionic compounds, and salts thereof. These are preferably other than the amine compounds used as accelerators as described above.

[0086] The corrosion inhibitor may be used alone or in combination of two or more types.

[0087] The content of the corrosion inhibitor in the etching composition according to this embodiment is not particularly limited, but is preferably 0.0001 to 1% by mass. The lower limit of this content is more preferably 0.0002% by mass or more, even more preferably 0.0003% by mass or more, and still more preferably 0.001% by mass or more. The upper limit of this content is more preferably 0.8% by mass or less, even more preferably 0.7% by mass or less, still more preferably 0.6% by mass or less, and still more preferably 0.5% by mass or less.

[0088] (pH adjuster)

[0089] The etching composition according to this embodiment may contain a pH adjusting agent to adjust to a desired pH. As the pH adjusting agent, inorganic acids, organic acids, organic basic compounds, and inorganic basic compounds can be used as appropriate. For example, sulfuric acid, sulfurous acid, and phosphoric acid are preferred.

[0090] pH adjusters may be used individually or in combination of two or more types.

[0091] The content of the pH adjusting agent in the etching composition according to this embodiment is not particularly limited, but is preferably 0.01 to 1% by mass. The lower limit of this content is more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, and still more preferably 0.15% by mass or more. The upper limit of this content is more preferably 0.8% by mass or less, even more preferably 0.6% by mass or less, still more preferably 0.5% by mass or less, and still more preferably 0.3% by mass or less.

[0092] (solvent)

[0093] The etching composition according to this embodiment may contain a solvent. For example, it is preferable that the solvent contains water. The etching composition according to this embodiment can be suitably used as an aqueous etching composition.

[0094] The water content in the etching composition according to this embodiment is not particularly limited, but is preferably 1 to 99% by mass. The lower limit of the water content is more preferably 25% by mass or more, even more preferably 35% by mass or more, even more preferably 45% by mass or more, even more preferably 50% by mass or more, even more preferably 55% by mass or more, even more preferably 60% by mass or more, even more preferably 80% by mass or more, and even more preferably 85% by mass or more. The upper limit of the water content is more preferably 99% by mass or less. By having a water content within the above range, other components can be dissolved uniformly and stably, and the desired effect can be maintained while imparting water solubility as an aqueous etching composition.

[0095] Furthermore, the etching composition according to this embodiment may contain an organic solvent. Specific examples of organic solvents are not particularly limited, but include at least one selected from the group consisting of alcohol-based solvents, glycol ether-based solvents, sulfoxide-based solvents, sulfone-based solvents, amide-based solvents, lactone-based solvents, imidazolidinone-based solvents, nitrile-based solvents, ketone-based solvents, ether-based solvents, acetate-based solvents, pyrrolidone-based solvents, and urea-based solvents. Among these, at least one selected from the group consisting of alcohol-based solvents, glycol ether-based solvents, sulfoxide-based solvents, sulfone-based solvents, amide-based solvents, imidazolidinone-based solvents, nitrile-based solvents, ketone-based solvents, ether-based solvents, pyrrolidone-based solvents, and urea-based solvents is preferred. Also, when the etching composition according to this embodiment contains an organic solvent, it is preferable to use a water-soluble organic solvent from the viewpoint of providing water solubility.

[0096] (Impurities, etc.)

[0097] The etching solution according to this embodiment may contain metallic impurities, such as at least one metal atom selected from the group consisting of Fe atoms, Cr atoms, Ni atoms, Zn atoms, Ca atoms, and Pb atoms.

[0098] The total content of metal atoms in the etching solution according to this embodiment is preferably 100 mass ppt or less relative to the total mass of the etching solution. The lower limit of the total content of metal atoms is preferable as it is lower, but for example, 0.001 mass ppt or more is acceptable. For example, the total content of metal atoms can range from 0.001 mass ppt to 100 mass ppt. It is believed that by setting the total content of metal atoms below the above-mentioned preferred upper limit, the defect suppression and residue suppression properties of the etching solution are improved. It is believed that by setting the total content of metal atoms above the above-mentioned preferred lower limit, metal atoms are less likely to be released and exist in the system, thus reducing the likelihood of adverse effects on the overall manufacturing yield of the object being cleaned.

[0099] The content of metal impurities can be adjusted, for example, by purification treatment such as filtering. This purification treatment may be performed on some or all of the raw materials before preparing the etching solution, or it may be performed after preparing the etching solution.

[0100] The etching solution according to this embodiment may contain, for example, impurities of organic origin (organic impurities). The total content of the above-mentioned organic impurities in the etching solution according to this embodiment is preferably 5000 ppm by mass or less. The lower limit of the organic impurity content is preferable as it is lower, but for example, 0.1 ppm by mass or more is acceptable. The total content of organic impurities can range from 0.1 ppm by mass to 5000 ppm by mass, for example.

[0101] The etching solution according to this embodiment may contain countable particles of a size that can be counted by, for example, a light scattering type liquid particle counter. The size of the countable particles is, for example, 0.04 μm or larger. The number of countable particles in the etching solution according to this embodiment is, for example, 1,000 or less per 1 mL of etching solution, with a lower limit of, for example, 0.1 or more. It is believed that the effect of the etching solution on suppressing metal corrosion and suppressing defects is improved by having the number of countable particles in the etching solution within the above range (however, the effects of this embodiment are not limited to these).

[0102] The organic impurities and / or substances to be counted described above may be added to the etching solution, or they may be inevitably introduced into the etching solution during the manufacturing process of the etching solution. Examples of cases where organic impurities are inevitably introduced during the manufacturing process of the etching solution include, but are not limited to, cases where organic impurities are contained in the raw materials used in the manufacture of the etching solution (e.g., organic solvents), and cases where they are introduced from the external environment during the manufacturing process of the etching solution (e.g., contamination).

[0103] When adding the material to be measured to the etching solution, the ratio of material present may be adjusted for each specific size, taking into consideration the surface roughness of the object to be cleaned.

[0104] (pH)

[0105] The pH of the etching composition according to this embodiment is not particularly limited, but is preferably 6 or less. The lower limit of the pH is preferably 1 or more, and more preferably 2 or more. The upper limit of the pH is more preferably 4.5 or less. For example, an example of a preferred combination of the upper and lower limits of the pH is 1 to 6. When the pH is within the above range, the selectivity of SiGe, the suppression of damage to Si, and the defoaming properties can be further improved. The pH can be controlled to a desired pH by adding the above-mentioned pH adjusting agents, etc.

[0106] <Etching Method>

[0107] The etching composition according to this embodiment can be suitably used for etching the laminated substrate described above. Specifically, a preferred embodiment of the etching method according to this embodiment is an etching method comprising a step (etching step) of etching a laminated substrate, which includes a substrate and a layer containing a silicon germanium alloy (SiGe) provided on the substrate, using an etching composition, wherein the etching composition contains (A) an oxidizing agent, (B) a compound or salt thereof capable of releasing fluoride ions, and (C) a nonionic surfactant selected from the group consisting of a compound represented by general formula (c1) (c1) and a compound represented by general formula (c2) (c2).

[0108] The etching composition used in the etching method according to this embodiment can be appropriately adapted from the contents of the etching composition described above. The laminated substrate to be processed by the etching method according to this embodiment can be appropriately adapted from the configuration of the laminated substrate and other contents described in the etching composition.

[0109] Furthermore, it is preferable that the etching method used in this embodiment further includes a preparation step before the etching step described above, in which a first chemical solution containing components (B) and (C) and a second chemical solution containing component (A) are mixed to prepare the etching composition. By preparing the first and second chemical solutions in advance and mixing them before (preferably immediately before) the etching step to prepare the etching composition before using it in the etching step, the decomposition of the oxidizing agent, which is component (A), over time can be effectively suppressed, thereby further improving the etching effect.

[0110] The first chemical solution may further contain other components besides component (A) in addition to components (B) and (C). For example, it may contain at least one selected from the group consisting of the accelerators, corrosion inhibitors, pH adjusters, and solvents mentioned above.

[0111] The second chemical solution may further contain other components in addition to the oxidizing agent, which is component (A). For example, it may further contain the solvent mentioned above. From the viewpoint of suppressing the decomposition of the oxidizing agent over time, it is preferable to contain only the oxidizing agent and a solvent (for example, water and / or an organic solvent). For example, it is preferable to use hydrogen peroxide or the like as the second chemical solution.

[0112] Furthermore, other chemical solutions (e.g., a third chemical solution, a fourth chemical solution, etc.) besides the first and second chemical solutions may also be prepared, and the first chemical solution, the second chemical solution, and the other chemical solutions may be mixed before the processing step to prepare the processing solution. Examples of other chemical solutions (e.g., a third chemical solution, a fourth chemical solution, etc.) include chemical solutions containing other components such as the pH adjuster and buffer mentioned above, and a solvent (e.g., water and / or an organic solvent).

[0113] When the first and second chemical solutions are prepared separately in this manner, they can be used as an etching kit. That is, the etching method can further include the steps of preparing a processing solution kit containing the first and second chemical solutions before the processing steps described above, and mixing the first and second chemical solutions to prepare a processing solution.

[0114] The processing conditions for the etching method according to this embodiment are not particularly limited, and suitable conditions can be selected considering the material and structure of the laminated substrate to be etched, as well as the level of the scale-up process. Examples of etching methods include immersion, spray, and liquid buildup methods.

[0115] For example, the processing temperature of the etching process is not particularly limited and may be 10 to 80°C. The lower limit of the processing temperature may be 15°C or higher, or 20°C or higher. The upper limit of the processing temperature may be 70°C or lower, 60°C or lower, 50°C or lower, 40°C or lower, or 30°C or lower.

[0116] For example, the processing time for the etching process is not particularly limited and may range from 10 seconds to 10 hours. The lower limit of the processing time may be 30 seconds or more, 1 minute or more, 5 minutes or more, 10 minutes or more, 15 minutes or more, 20 minutes or more, 25 minutes or more, or 30 minutes or more. The upper limit of the processing time may be 8 hours or less, 5 hours or less, 3 hours or less, 2 hours or less, or 1 hour or less.

[0117] In the etching method according to this embodiment, the etching step is preferably a step in which etching is performed in an etching apparatus connected to a tank filled with an etching composition (etching solution). According to this embodiment, since it has at least the advantage of excellent defoaming properties as described above, it can effectively suppress the problem of bubbles that tend to occur when the etching composition etched in the etching apparatus is sent to the tank, thereby effectively demonstrating advantages that could not be achieved in the prior art.

[0118] In the etching method according to this embodiment, it is preferable that the tank is equipped with a circulation unit that refills the tank with used etching composition used in the etching process, and that the method includes a step of refilling the tank with the used etching composition (reuse step). This is suitable when performing a single-wafer etching process in which the first cycle of etching of a laminated substrate is performed in the etching apparatus, the laminated substrate is removed from the etching apparatus after the process, and then another laminated substrate is put back into the etching apparatus for the second cycle of etching. The etching solution used in the first cycle (used etching solution) can be circulated and sent back to the etching apparatus for use in the second cycle of etching.

[0119] In this embodiment, the etching method comprises a processing unit for regenerating a used etching composition and a circulation unit for refilling a tank with the regenerated etching composition. Preferably, the method includes a step of regenerating the used etching composition used in the etching process by the processing unit (regeneration step) and a step of refilling the tank with the regenerated etching composition by the circulation unit. In this case, after the used etching composition is discharged from the tank, a step of filtering impurities from the etching composition and / or replenishing active ingredients (regeneration step) is performed. The etching composition thus regenerated can be sent back into the tank and used in the next etching cycle.

[0120] When performing the reuse and recycling processes described above, undesirable foaming tends to occur when the etching composition is supplied to the tank, which can easily lead to false readings by the water level detection unit (e.g., water level gauge, level gauge, etc.) installed in the tank. However, since the etching composition of this embodiment has excellent defoaming properties, such problems can be effectively suppressed.

[0121] In the etching method according to this embodiment, it is preferable to perform a cleaning step to clean the laminated substrate before the etching step. The cleaning step can be performed using a known cleaning solution. Examples of cleaning solutions include hydrogen fluoride water (HF water). Cleaning can be performed by bringing the cleaning solution into contact with the laminated substrate using methods such as rotary coating, dipping, spraying, or paddle coating. Cleaning can be performed at atmospheric pressure and room temperature (approximately 15-30°C). Examples of contact times between the cleaning solution and the laminated substrate include 10-180 seconds, 20-120 seconds, and 30-60 seconds.

[0122] In the etching method according to this embodiment, it is preferable to perform a cleaning step and / or a drying step after the etching step. The cleaning step after etching can be performed using a known cleaning solution. Examples of cleaning solutions include water. Cleaning can be performed by bringing the cleaning solution into contact with the laminated substrate by methods such as rotary coating, dipping, spraying, or paddle coating. Cleaning can be performed at atmospheric pressure and room temperature (approximately 15-30°C). Examples of contact times between the cleaning solution and the laminated substrate include 10-180 seconds, 20-120 seconds, and 30-60 seconds. For the drying step, a drying method such as natural drying or nitrogen blowing can be employed.

[0123] <Manufacturing method for semiconductor substrates>

[0124] The etching composition and etching method according to this embodiment can be suitably used in a semiconductor substrate manufacturing method. A preferred embodiment of the semiconductor substrate manufacturing method according to this embodiment is a semiconductor substrate manufacturing method comprising the steps of etching a laminated substrate, which includes a substrate and a layer containing a silicon germanium alloy (SiGe) provided on the substrate, using an etching composition, and cleaning the etched laminated substrate with a cleaning solution, wherein the etching composition comprises (A) an oxidizing agent, (B) a compound or salt thereof capable of releasing fluoride ions, and (C) a nonionic surfactant containing at least one selected from the group consisting of a compound represented by general formula (c1) (c1) and a compound represented by general formula (c2) (c2). The etching composition used in the semiconductor substrate manufacturing method according to this embodiment can be appropriately adopted from the etching composition described above. The laminated substrate used in the semiconductor substrate manufacturing method according to this embodiment can be appropriately adopted from the configuration of the laminated substrate described in the etching composition and other details. [Examples]

[0125] The present invention will be further described in detail by the following examples and comparative examples, but the present invention is not limited in any way by the following examples. Unless otherwise specified, the numerical values ​​are based on mass.

[0126] <Examples 1-28, Comparative Examples 1-4> Etching solutions having the compositions shown in each table were prepared. For example, the etching solution of Example 1 contains 2% by mass of hydrogen peroxide (H2O2), 0.1% by mass of hydrogen fluoride (HF), 0.0005% by mass of "Softanol 90" as a surfactant, 0.08% by mass of "Acetylenel E40" as an additive, 0.08% by mass of ethylenediamine (EDA), and the remainder being water (deionized water, DIW).

[0127] <Ingredient names and abbreviations, etc.> The following supplementary information is provided regarding the ingredient names and abbreviations shown in the table.

[0128] (Surfactants) • "Softanol 90": Manufactured by Nippon Shokubai Co., Ltd., trade name "Softanol (registered trademark) 90," it is a nonionic surfactant represented by the following formula, and its Griffin HLB calculation value is 13.3 (average number of moles of ethylene oxide groups added is 9). It is a surfactant having the structure of the general formula (c1) described above.

[0129] [ka]

[0130] (In the formula, a, b, and c each represent numbers independently, a + b = 9 to 11, and c has an average value of 9.)

[0131] • "TERGITOL TMN-10": Manufactured by DOW Corporation, trade name "TERGITOL (trademark) TMN-10," it is a surfactant represented by the following formula. It is a surfactant having the structure of the general formula (c1) described above.

[0132] [ka]

[0133] (In the formula, d represents a number, and its average value is 11.)

[0134] • "P-PE61": Manufactured by Chunichi Synthetic Chemical Co., Ltd., trade name "P-PE61", it is a surfactant having the structure of the general formula (c2) described above.

[0135] [ka]

[0136] (In the formula, A is a divalent group containing structural unit (c2-1) represented by formula (c2-1) and structural unit (c2-2) represented by formula (c2-2), with an average number of added moles of structural unit (c2-1) being 1, an average number of added moles of structural unit (c2-2) being 6, and z representing a number between 8 and 16.)

[0137] [ka]

[0138] • "Softanol EP9050": Manufactured by Nippon Shokubai Co., Ltd., product name "Softanol (registered trademark) EP9050", is a surfactant having the structure of the general formula (c2) described above. [ka]

[0139] (In the formula, g represents a number with an average value of 5, h represents a number with an average value of 9, e represents a number between 0 and 11, and f represents a number between 0 and 11. Therefore, e + f = 9 to 11.)

[0140] • "TERGITOL TMN-6": Manufactured by DOW Corporation, trade name "TERGITOL (trademark) TMN-6," it is a surfactant represented by the following formula. It is a surfactant having the structure of the general formula (c1) described above.

[0141] [ka]

[0142] (In the formula, d represents a number, and its average value is 8.)

[0143] • "Softanol 50": Manufactured by Nippon Shokubai Co., Ltd., trade name "Softanol (registered trademark) 50," it is a nonionic surfactant represented by the following formula, and its calculated HLB value in Griffin is 10.5. It is a surfactant having the structure of the general formula (c1) described above. The HLB (Hydrophile-Lipophile Balance) value in Griffin is one of the indicators that represents the degree of affinity of a surfactant to water and oil (organic compounds insoluble in water), and can be calculated by 20 × sum of the formula weights of the hydrophilic parts / molecular weight.

[0144] [ka]

[0145] (In the equation, a represents a number between 0 and 11, b represents a number between 0 and 11, and c represents a number whose average value is 5. Therefore, a + b = 9 to 11.)

[0146] • "Softanol 70": Manufactured by Nippon Shokubai Co., Ltd., trade name "Softanol (registered trademark) 70," it is a nonionic surfactant represented by the following formula, and its Griffin HLB calculation value is 12.1. It is a surfactant having the structure of the general formula (c1) described above.

[0147] [ka]

[0148] (In the equation, a represents a number between 0 and 11, b represents a number between 0 and 11, c represents a number, and the average value is 5. Furthermore, a + b = 9 to 11.)

[0149] • "TERGITOL 15-S-5": Manufactured by DOW, trade name "TERGITOL(trademark) 15-S-5," it is a surfactant represented by the following formula. It is a surfactant having the structure of the general formula (c1) described above.

[0150] [ka]

[0151] (In the formula, a represents a number from 0 to 11, b represents a number from 0 to 11, c represents a number, and the average value is 5. And a + b = 9 to 11.) · "Acetylenol E00": Manufactured by Kawaken Fine Chemicals Co., Ltd., trade name "Acetylenol (registered trademark) E00", an acetylene glycol having a structure represented by the following formula.

[0152]

Chemical formula

[0153] · "Triton X-100": Manufactured by Kishida Chemical Co., Ltd., trade name "Triton (trademark) X-100", a polyethylene glycol octylphenyl ether having a structure represented by the following formula.

[0154]

Chemical formula

[0155] (In the formula, j is a number with an average value from 9 to 10.)

[0156] (Corrosion inhibitor) · "Acetylenol E40": Manufactured by Kawaken Fine Chemicals Co., Ltd., trade name "Acetylenol (registered trademark) E40", an acetylene glycol having a structure represented by the following formula.

[0157]

Chemical formula

[0158] (In the formula, s and t each independently represent a number, and the average value of s + t is 4.)

[0159] <Measurement of pH> The pH of the etching solution was measured at a temperature of 25°C using a pH / ORP meter (portable pH meter "ORION STAR A324", manufactured by Thermo Scientific).

[0160] <Measurement of etching rate> First, laminates (blanket wafers) with each metal layer on a substrate were fabricated as shown below. • SiGe on a substrate (12-inch silicon substrate) 40 A laminate (blanket wafer) on which layers (silicon germanium alloy with a Si60:Ge40 concentration ratio, film thickness 20 nm) have been deposited. • SiGe on a substrate (12-inch silicon substrate) 20 A laminated structure (blanket wafer) with a layer (silicon germanium alloy with a Si80:Ge20 concentration ratio, film thickness 20 nm) deposited on it. A laminate (blanket wafer) formed by depositing a Si layer (thickness 20 nm) on a substrate (12-inch silicon substrate). Next, each of the resulting laminates was cut into 2cm x 2cm sections when viewed from above to obtain test samples (wafer coupons). As a pretreatment, the samples were immersed in 0.5% by mass hydrogen fluoride solution (HF water) for 1 minute, then washed and dried. Subsequently, 100 mL of etching solution for each example and comparative example was placed in a 200 mL cup. The sample was then added and processed by stirring at a processing temperature of 25°C and a speed of 300 rpm. The processing time was determined by SiGe 40 For a laminated layer, the time is 1 minute, and SiGe 20 The etching time was 10 minutes for laminated layers and 20 minutes for laminated Si layers. After processing, the samples were removed from the etching solution, washed with water at room temperature for 30 seconds, and dried by nitrogen blowing.

[0161] And then, SiGe 40 SiGe 20For Si and SiGe, the film thickness reduction after the treatment was evaluated by measuring the etching rate (ER, Å / min) after the treatment with respect to that before the treatment. It was determined that the damage to the metal layer was suppressed more as the etching rate of the metal layer was lower. The film thickness before the treatment and the film thickness after the treatment were measured by the following methods. ·SiGe 40 and SiGe 20 The film thickness was measured using a scanning fluorescence X-ray analyzer (ZSX PrimusIV, manufactured by Rigaku Corporation). ·The film thickness of Si was measured using an ellipsometer (L115S300 STOKES WAFERSKAN, manufactured by Gaertner Scientific Corporation).

[0162] <​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Table 1 shows the composition and pH of the etching solutions for Examples 1-17, and Table 2 shows the composition and pH of the etching solutions for Examples 18-31 and Comparative Examples 1-4. Table 3 shows the evaluation results for Examples 1-31 and Comparative Examples 1-4.

[0165] [Table 1]

[0166] [Table 2]

[0167] [Table 3]

[0168] Based on the above, it has been confirmed that this embodiment exhibits excellent selectivity for SiGe and suppression of damage to Si, as well as excellent defoaming properties.

Claims

1. (A) Oxidizing agent, (B) A compound or salt thereof capable of releasing fluoride ions, (C) An etching composition comprising a nonionic surfactant selected from the group consisting of a compound (c1) represented by the following general formula (c1) and a compound (c2) represented by the following general formula (c2). 【Chemistry 1】 (In general formula (c1), x, y, and n represent numbers greater than or equal to 1.) 【Chemistry 2】 (In general formula (c2), A is a divalent group containing the structural unit (c2-1) represented by the following formula (c2-1) and the structural unit (c2-2) represented by the following formula (c2-2), and z represents a number of 1 or more.) 【Transformation 3】

2. The aforementioned component (A) includes at least one selected from the group consisting of hydrogen peroxide and oxoacids. The etching composition according to claim 1.

3. The aforementioned component (B) is at least one selected from the group consisting of hydrogen fluoride, ammonium fluoride, ammonium hydrogen fluoride, triethanolammonium fluoride, diglycolammonium fluoride, methyldiethanolammonium fluoride, tetramethylammonium fluoride, triethylamine trihydrofluoride, fluoroboric acid, tetrafluoroboric acid, ammonium tetrafluoroborate, fluoroacetic acid, ammonium fluoroacetate, trifluoroacetic acid, silicon fluoride, ammonium silicon fluoride, and tetrabutylammonium tetrafluoroborate. The etching composition according to claim 1 or 2.

4. The content of component (A) is 0.01 to 20% by mass. The etching composition according to claim 1 or 2.

5. The content of component (B) is 0.01 to 10% by mass. The etching composition according to claim 4.

6. The content of component (C) is 0.0001 to 3% by mass. The etching composition according to claim 1 or 2.

7. It also contains water, The etching composition according to claim 1 or 2.

8. The pH is 6 or less. The etching composition according to claim 7.

9. This is an etching composition for selectively etching layers containing silicon germanium alloy (SiGe). The etching composition according to claim 1 or 2.

10. An etching method comprising the step of etching a laminated substrate, which includes a substrate and a layer containing a silicon germanium alloy (SiGe) provided on the substrate, using an etching composition. The etching composition, (A) Oxidizing agent, (B) A compound or salt thereof capable of releasing fluoride ions, (C) A nonionic surfactant comprising at least one compound selected from the group consisting of a compound represented by the following general formula (c1) (c1) and a compound represented by the following general formula (c2) (c2), Etching method. 【Chemistry 4】 (In general formula (c1), x, y, and n represent numbers greater than or equal to 1.) 【Transformation 5】 (In general formula (c2), A is a divalent group containing the structural unit (c2-1) represented by the following formula (c2-1) and the structural unit (c2-2) represented by the following formula (c2-2), and z represents a number of 1 or more.) 【Transformation 6】

11. A laminated substrate comprising a substrate and a layer containing a silicon germanium alloy (SiGe) provided on the substrate, is etched using an etching composition. A method for manufacturing a semiconductor substrate, comprising the step of cleaning the etched laminated substrate with a cleaning solution, The etching composition, (A) Oxidizing agent, (B) A compound or salt thereof capable of releasing fluoride ions, (C) A nonionic surfactant comprising at least one compound selected from the group consisting of a compound represented by the following general formula (c1) (c1) and a compound represented by the following general formula (c2) (c2), A method for manufacturing semiconductor substrates. 【Transformation 7】 (In general formula (c1), x, y, and n represent numbers greater than or equal to 1.) 【Transformation 8】 (In general formula (c2), A is a divalent group containing the structural unit (c2-1) represented by the following formula (c2-1) and the structural unit (c2-2) represented by the following formula (c2-2), and z represents a number of 1 or more.) 【Chemistry 9】

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