Etching solution and method for manufacturing semiconductor device

Abstract

To provide an etchant by which a compound represented by the general formula, Si1-xGex can be etched selectively rather than Si, Ge and their oxides, and a method for manufacturing a semiconductor by use of the etchant.SOLUTION: An etchant for selectively etching a compound (where x is larger than 0 and smaller than 1) represented by the general formula, Si1-xGex rather than Si, Ge and their oxides comprises: fluoride; and an oxidizer. As to the etchant, the fluoride includes a hexafluoro silicate, and an etching rate A measured under the following condition is 10 Å / min or more. (Measurement Condition of A)On condition that a blanket substrate having a layer of Si0.75Ge0.25 on its surface is immersed in the etchant at 25°C, the etching rate is measured.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Traditionally, scaling the configuration within integrated circuits has enabled higher density of functional units on semiconductor chips. For example, reducing transistor size allows for the inclusion of more memory elements on a chip, leading to the manufacture of products with increased capacity.

[0003] In the manufacture of field-effect transistors (FETs) for integrated circuit devices, ge (Ge) is used as a semiconductor crystalline material other than silicon. Ge has several advantages over silicon in some cases, including high charge carrier (hole) mobility, bandgap offset, different lattice constants, and the ability to alloy with silicon to produce SiGe semiconductor binary alloys.

[0004] Ge materials (especially those with the general formula Si 1-x Ge x A compound represented by , where x is greater than 0 and less than 1. Hereinafter, it may simply be referred to as a "SiGe compound." Various etching solutions with high selectivity for ) have been proposed. For example, Patent Document 1 contains at least one diol compound and at least one fluoride An etching composition comprising a substance and at least one oxidizing species is described. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Special Publication No. 2018-519674 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, when using a conventional etching solution as described in Patent Document 1, not only the SiGe compound but also Si, SiO2, etc. are etched, making it difficult to selectively etch the SiGe compound with respect to Si, SiO2, etc. The present invention has been made in view of the above circumstances, and an object thereof is to provide an etching solution capable of selectively etching a compound represented by the general formula Si 1-x Ge x with respect to Si, Ge, and their oxides, and a method for manufacturing a semiconductor using the etching solution.

Means for Solving the Problems

[0007] In order to solve the above problems, the present invention adopts the following configuration.

[0008] The first aspect of the present invention is an etching solution for selectively etching a compound represented by the general formula Si 1-x Ge x (where x is greater than 0 and less than 1) with respect to Si, Ge, and their oxides, which contains a fluoride and an oxidizing agent, the fluoride contains hexafluorosilicic acid, and the etching rate A measured under the following conditions is 10 Å / min or more. (A measurement conditions) A blanket substrate having a layer of Si 0.75 Ge 0.25 on its surface is immersed in the etching solution at 25°C, and the etching rate is measured.

[0009] The second aspect of the present invention is a method for manufacturing a semiconductor device, which includes a step of etching a workpiece containing a compound represented by the general formula Si 1-x Ge x using the above etching solution.

Effects of the Invention

[0010] According to the etching solution of the present invention, a compound represented by the general formula Si 1-x Ge x can be selectively etched with respect to Si, Ge, and their oxides. Also, according to the method for manufacturing a semiconductor of the present invention, a semiconductor in which a compound represented by the general formula Si 1-x Ge x is selectively etched can be manufactured for Si, Ge, and their oxides.

Embodiments for Carrying Out the Invention

[0011] (Etching solution) The etching solution according to the first aspect of the present invention contains a fluoride and an oxidizing agent, and the fluoride contains hexafluorosilicic acid. The etching solution according to this aspect is used to selectively etch a compound represented by the general formula Si 1-x Ge x where x is greater than 0 and less than 1 (hereinafter sometimes simply referred to as "SiGe compound") for Si, Ge, and their oxides.

[0012] The etching solution of this embodiment has an etching rate A measured under the following conditions of 10 Å / min or more, preferably 15 Å / min or more, more preferably 20 Å / min or more, still more preferably 50 Å / min or more, and particularly preferably 80 Å / min or more. (A measurement conditions) A blanket substrate having a layer of Si 0.75 Ge 0.25 on its surface is immersed in the etching solution at 25°C, and the etching rate is measured.

[0013] The etching solution of this embodiment has good selectivity for the SiGe compound because the etching rate A is 10 Å / min or more. Also, when the etching rate A of the etching solution of this embodiment is at least the lower limit value of the above preferred range, the selectivity for the SiGe compound is further enhanced.

[0014] When the etching rate measured under the following conditions of the etching solution of the present embodiment is defined as etching rate B, it is preferable that A / B is 10 or more, more preferably A / B is 15 or more, still more preferably A / B is 20 or more, still more preferably A / B is 30 or more, still more preferably A / B is 70 or more, and particularly preferably A / B is 90 or more. (B measurement conditions) A blanket substrate having a SiO2 layer on its surface is immersed in the etching solution at 25°C, and the etching rate is measured.

[0015] Since A / B of the etching solution of the present embodiment is at least the lower limit of the above preferred range, the etching selectivity of the SiGe compound with respect to SiO2 is further enhanced.

[0016] <Fluoride> The etching solution according to the present embodiment contains hexafluorosilicic acid as a fluoride. Fluorides other than hexafluorosilicic acid are not particularly limited, and include hexafluorotitanic acid, hexafluorosilicic acid, hexafluorozirconic acid, tetrafluoroboric acid, tetrabutylammonium trifluoromethanesulfonate, tetraalkylammonium tetrafluoroborate (NR1R2R3R4BF4) such as tetrabutylammonium tetrafluoroborate, tetraalkylammonium hexafluorophosphate (NR1R2R3R4PF6), tetraalkylammonium fluoride (NR1R2R3R4F) (anhydride or hydrate) such as tetramethylammonium fluoride, ammonium bifluoride, ammonium fluoride (wherein, R1, R2, R3, and R4 may be the same as or different from each other, and are selected from the group consisting of hydrogen, linear or branched C1-C6 alkyl groups (e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl), C1-C6 alkoxy groups (e.g., hydroxyethyl, hydroxypropyl), or substituted or unsubstituted aryl groups (e.g., benzyl)). In the etching solution according to the present embodiment, it is preferable to contain only hexafluorosilicic acid as a fluoride.

[0017] In the etching solution of this embodiment, one type of fluoride may be used alone, or two or more types may be used in combination. The fluoride content in the etching solution of this embodiment is not particularly limited, but for example, 0.02 to 5% by mass is exemplified, preferably 0.025 to 3.00% by mass, more preferably 0.03 to 2.50% by mass, and even more preferably 0.04 to 2.00% by mass, based on the total mass of the etching solution. When the fluoride content is within the above range, the etching rate for SiGe compounds tends to improve more easily.

[0018] Furthermore, the fluoride ion concentration of the etching solution in this embodiment is not particularly limited, but for example, 0.005 to 2.50 mol / L is exemplified, 0.007 to 1.50 mol / L is preferred, 0.008 to 1.25 mol / L is more preferred, and 0.010 to 1.00 mol / L is even more preferred. When the fluoride ion concentration is within the above range, the fluoride ion concentration relative to the SiGe compound The etching rate is more likely to improve.

[0019] <Oxidizing agent> Oxidizing agents include, for example, hydrogen peroxide, FeCl3, FeF3, Fe(NO3)3, Sr(NO3)2, CoF3, MnF3, oxone (2KHSO5·KHSO4·K2SO4), iodic acid, vanadium(V) oxide, vanadium(IV,V) oxide, ammonium vanadate, ammonium peroxomonosulfate, ammonium chlorite, ammonium chlorate, ammonium iodate, ammonium nitrate, ammonium perborate, ammonium perchlorate, ammonium periodate, ammonium persulfate, ammonium hypochlorite, ammonium hypobromite, ammonium tungstate, sodium persulfate, sodium hypochlorite, sodium perborate, sodium hypobromite, potassium iodate, potassium permanganate, potassium persulfate, nitric acid, potassium persulfate, potassium hypochlorite Examples include tetramethylammonium chlorite, tetramethylammonium chlorate, tetramethylammonium iodate, tetramethylammonium perborate, tetramethylammonium perchlorate, tetramethylammonium periodate, tetramethylammonium persulfate, tetrabutylammonium peroxomonosulfate, peroxomonosulfate, ferric nitrate, urea peroxide, peracetic acid, orthoperiodic acid (H5IO6), metaperiodic acid (HIO4), methyl-1,4-benzoquinone (MBQ), 1,4-benzoquinone (BQ), 1,2-benzoquinone, 2,6-dichloro-1,4-benzoquinone (DCBQ), tolquinone, 2,6-dimethyl-1,4-benzoquinone (DMBQ), chloranil, alloxane, N-methylmorpholine N-oxide, trimethylamine N-oxide, etc. Among these, nitric acid or orthoperiodic acid is preferred as the oxidizing agent, with nitric acid being more preferred.

[0020] In the etching solution of this embodiment, one type of oxidizing agent may be used alone, or two or more types may be used in combination. The content of the oxidizing agent in the etching solution of this embodiment is, for example, 5 to 50% by mass, preferably 5.5 to 45% by mass, more preferably 6 to 40% by mass, and even more preferably 7 to 35% by mass, based on the total mass of the etching solution. When the content of the oxidizing agent is within the aforementioned range, the SiGe compound is more easily oxidized, and the etching rate for the SiGe compound tends to improve further.

[0021] <Other ingredients> The etching solution of this embodiment may contain other components in addition to the above components, as long as the effects of the present invention are not impaired. Examples of other components include solvents, pH adjusters, passivation agents, surfactants, and the like.

[0022] ·solvent The etching solution of this embodiment is preferably prepared by mixing hydrofluoric acid, an oxidizing agent, and other optional components in a solvent. The solvent is not particularly limited and includes water, polar organic solvents, phosphoric acid and / or its derivatives.

[0023] ·water In this embodiment, if the etching solution contains water as a solvent, the water may contain trace components that are inevitably mixed in. The water used in the etching solution of this embodiment is preferably purified water such as distilled water, ion-exchanged water, and ultrapure water, and it is more preferable to use ultrapure water which is commonly used in semiconductor manufacturing. When the etching solution of this embodiment contains water, the water content is exemplified as 3 to 50% by mass, preferably 3.5 to 45% by mass, and 4 to 40% by mass, relative to the total mass of the etching solution. % is more preferable, and 4.5 to 40% by mass is even more preferable.

[0024] • Polar organic solvents The etching solution of this embodiment may contain a polar organic solvent, to the extent that it does not impair the effects of the present invention. Examples of polar organic solvents include organic carboxylic acid solvents (e.g., acetic acid, formic acid, etc.), alcohol solvents (e.g., methanol, ethanol, ethylene glycol, propylene glycol, glycerin, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, diethylene glycol, dipropylene glycol, furfuryl alcohol, and 2-methyl-2,4-pentanediol, etc.), dimethyl sulfoxides, ether solvents (e.g., ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, propylene glycol dimethyl ether, etc.). Among these, organic carboxylic acid solvents are preferred as polar organic solvents, and acetic acid is more preferred.

[0025] In the etching solution of this embodiment, one polar organic solvent may be used alone, or two or more may be used in combination. When the etching solution of this embodiment contains a polar organic solvent, the content of the polar organic solvent is, for example, exemplified as 20 to 90% by mass, preferably 25 to 85% by mass, more preferably 30 to 80% by mass, and even more preferably 35 to 75% by mass, based on the total mass of the etching solution.

[0026] • Phosphates and their derivatives The etching solution of this embodiment may contain phosphoric acid and / or its derivatives as a solvent, to the extent that it does not impair the effects of the present invention. Examples of phosphoric acid and / or its derivatives include compounds represented by the following general formula (1).

[0027] [Formula 1] [In the formula, each R is independently either a hydrogen atom or an alkyl group having 1 to 20 carbon atoms.]

[0028] In formula (1) above, examples of C1-C20 alkyl groups in R include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, isotridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, isohexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group, and various isomers of the above alkyl groups. In particular, R is preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and more preferably a hydrogen atom.

[0029] In the etching solution of this embodiment, phosphoric acid and / or its derivatives may be used alone as a solvent, or two or more may be used in combination. When the etching solution of this embodiment contains phosphoric acid and / or its derivatives as a solvent, the content of phosphoric acid and / or its derivatives is, for example, 1 to 50% by mass, preferably 2 to 45% by mass, more preferably 3 to 40% by mass, and even more preferably 5 to 35% by mass, based on the total mass of the etching solution.

[0030] In the etching solution of this embodiment, one solvent may be used alone, or two or more solvents may be used in combination. In the etching solution of this embodiment, when two or more solvents are used in combination, a combination of water and a polar organic solvent or a combination of water and phosphoric acid and / or its derivatives is preferred. A combination of water and an organic carboxylic acid solvent or a combination of water and phosphoric acid and / or its derivatives is more preferred, and a combination of water and acetic acid or a combination of water and phosphoric acid is even more preferred.

[0031] When the etching solution of this embodiment contains a combination of water and a polar organic solvent as a solvent, the mass ratio of water to the polar organic solvent is preferably 1 / 15 to 1 / 1, more preferably 1 / 12 to 9 / 10, and even more preferably 1 / 10 to 8 / 10.

[0032] When the etching solution of this embodiment contains a combination of water and phosphoric acid and / or its derivatives as a solvent, the mass ratio of water to polar organic solvent is preferably 1 / 1 to 10 / 1, more preferably 1.1 / 1 to 9 / 1, and even more preferably 1.2 / 1 to 8 / 1.

[0033] If the etching solution of this embodiment contains a solvent, the solvent content is exemplified as 23 to 95% by mass, preferably 23.5 to 94.5% by mass, more preferably 24 to 94% by mass, and even more preferably 24.5 to 93.5% by mass, based on the total mass of the etching solution.

[0034] • pH adjuster The etching solution of this embodiment may contain a pH adjuster to further improve the etching rate for SiGe compounds. As a pH adjuster, at least one selected from the group consisting of acids and their salts is preferred. Specifically, methanesulfonic acid, trifluoromethanesulfonic acid, oxalic acid dihydrate, citric acid, tartaric acid, picolinic acid, succinic acid, acetic acid, lactic acid, sulfosuccinic acid, benzoic acid, propionic acid, formic acid, pyruvic acid, maleic acid, malonic acid, fumaric acid, malic acid, ascorbic acid, mandelic acid, heptanoic acid, butyric acid, valeric acid, glutaric acid, phthalic acid, hypophosphorous acid, salicylic acid, 5-sulfosalicylic acid, hydrochloric acid, ethanesulfonic acid, butanesulfonic acid, p-toluenesulfonic acid, dichloroacetic acid, difluoroacetic acid, monochloroacetic acid, monofluoroacetic acid, trichloroacetic acid, trifluoroacetic acid, hydrobromic acid (62% by weight), sulfuric acid, ammonium acetate, sodium acetate, potassium acetate, tetramethylammonium acetate and other tetraacetic acids. Examples include alalkylammonium, phosphonium acetate, ammonium butyrate, ammonium trifluoroacetate, ammonium carbonate, ammonium chloride, ammonium sulfate, phosphoric acid, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, bis(tetramethylammonium) hydrogen phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, ditetraalkylammonium hydrogen phosphate, ditetraalkylammonium hydrogen phosphate, diphosphonium hydrogen phosphate, phosphonium dihydrogen phosphate, ammonium phosphonate, tetraalkylammonium phosphonate, sodium phosphonate, potassium phosphonate, phosphonium phosphonate, etidronic acid, and their salts. In particular, methanesulfonic acid or oxalic acid are preferred as pH adjusting agents.

[0035] Furthermore, the etching solution of this embodiment may contain a basic compound as a pH adjuster. Such basic compounds can be organic alkaline compounds or inorganic alkaline compounds. Suitable examples of organic alkaline compounds include quaternary ammonium salts, including organic quaternary ammonium hydroxide, and salts of alkylamines such as trimethylamine and triethylamine, and their derivatives. In addition, inorganic alkaline compounds include inorganic compounds containing alkali metals or alkaline earth metals and their salts. Examples include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide.

[0036] In the etching solution of this embodiment, one pH adjusting agent may be used alone, or two types may be used. You may use the above methods in combination. When the etching solution of this embodiment contains a pH adjusting agent, the content of the pH adjusting agent is exemplified as 0.01 to 10% by mass, preferably 0.02 to 4.5% by mass, more preferably 0.03 to 4% by mass, and even more preferably 0.05 to 3% by mass, based on the total mass of the etching solution. When the content of the pH adjusting agent is within the above range, the etching rate for SiGe compounds tends to improve more easily.

[0037] • Passivation agent The etching solution of this embodiment may contain a passivation agent for germanium. Passivation agents include ascorbic acid, L(+)-ascorbic acid, isoascorbic acid, ascorbic acid derivatives, boric acid, ammonium diborate, borates (e.g., ammonium pentaborate, sodium tetraborate, and ammonium diborate), alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine, sodium bromide, potassium bromide, rubidium bromide, magnesium bromide, calcium bromide, formula NR 1 R 2 R 3 R 4 Br (wherein, R 1 , R 2 , R 3 and R 4Examples include ammonium bromide, which has hydrogen and branched or straight-chain C1-C6 alkyl groups (e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl), which may be the same or different from each other.

[0038] In the etching solution of this embodiment, the passivation agent may be used alone or in combination of two or more types. If the etching solution of this embodiment contains a passivation agent, for example, 0.01 to 5% by mass, and more preferably 0.1 to 1% by mass, is preferred based on the total mass of the etching solution.

[0039] • Surfactants The etching solution of this embodiment may contain a surfactant for purposes such as adjusting the wettability of the etching solution to the workpiece. Nonionic surfactants, anionic surfactants, cationic surfactants, or amphoteric surfactants can be used as the surfactant, and these may be used in combination.

[0040] Examples of nonionic surfactants include polyalkylene oxide alkylphenyl ether surfactants, polyalkylene oxide alkyl ether surfactants, block polymer surfactants consisting of polyethylene oxide and polypropylene oxide, polyoxyalkylene distyrene-phenyl ether surfactants, polyalkylene rivenzyl phenyl ether surfactants, and acetylene polyalkylene oxide surfactants.

[0041] Examples of anionic surfactants include alkyl sulfonic acid, alkylbenzene sulfonic acid, alkylnaphthalene sulfonic acid, alkyldiphenyl ether sulfonic acid, fatty acid amide sulfonic acid, polyoxyethylene alkyl ether carboxylic acid, polyoxyethylene alkyl ether acetic acid, polyoxyethylene alkyl ether propionic acid, alkylphosphonic acid, and fatty acid salts. Examples of "salts" include ammonium salts, sodium salts, potassium salts, and tetramethylammonium salts.

[0042] Examples of cationic surfactants include quaternary ammonium salt-based surfactants and alkylpyridium-based surfactants.

[0043] Examples of amphoteric surfactants include betaine-type surfactants, amino acid-type surfactants, imidazoline-type surfactants, and amine oxide-type surfactants.

[0044] These surfactants are generally commercially available. Surfactants may be used individually or in combination of two or more.

[0045] <Object to be processed> The etching solution of this embodiment is used for etching SiGe compounds, and the workpiece containing SiGe compounds is the target of the etching process. The workpiece is not particularly limited as long as it contains SiGe compounds, but examples include substrates having a SiGe compound-containing layer (SiGe compound-containing film). The substrate is not particularly limited and examples include semiconductor wafers, photomask glass substrates, liquid crystal display glass substrates, plasma display glass substrates, FED (Field Emission Display) substrates, optical disk substrates, magnetic disk substrates, magneto-optical disk substrates, and various other substrates. A substrate used for manufacturing semiconductor devices is preferred as the substrate. In addition to the SiGe compound-containing layer and the substrate base, the substrate may have various layers and structures as appropriate, such as metal wiring, gate structures, source structures, drain structures, insulating layers, ferromagnetic layers, and non-magnetic layers. Furthermore, the uppermost layer on the device surface of the substrate does not need to be the SiGe compound-containing layer; for example, an intermediate layer in a multilayer structure may be the SiGe compound-containing layer. There are no particular restrictions on the size, thickness, shape, or layer structure of the substrate; it can be appropriately selected according to the purpose.

[0046] The SiGe compound-containing layer is preferably a layer containing a SiGe compound, and more preferably a SiGe compound film. The thickness of the SiGe compound-containing layer on the substrate is not particularly limited and can be appropriately selected depending on the purpose. Examples of the thickness of the SiGe compound-containing layer include the range of 1 to 500 nm and 1 to 300 nm.

[0047] The treated material may contain, in addition to the SiGe compound, at least one selected from the group consisting of Si, Ge, and oxides thereof, and preferably contains SiO2.

[0048] The etching solution of this embodiment may be used to perform microfabrication of a SiGe compound-containing layer on a substrate, to remove SiGe compound-containing deposits adhering to a substrate, or to remove impurities such as particles from a workpiece having a SiGe compound-containing layer on its surface.

[0049] As described above, the etching solution of this embodiment contains hexafluorosilicic acid as a fluoride, and therefore, the general formula Si is used for Si, Ge, and their oxides. 1-x Ge x It is possible to selectively etch compounds represented by (SiGe compounds). The reason for this is not clear, but it is presumed to be as follows: When the etching solution of this embodiment is brought into contact with a workpiece containing a SiGe compound, the SiGe compound is oxidized by the oxidizing agent. The oxide of the SiGe compound is fluoride ions (F) in hexafluorosilicic acid. - ) is etched by ). On the other hand, silicon (Si) in hexafluorosilicic acid is etched by fluoride ions (F) of Si and SiO2 etc. in the object to be treated. - It provides protection from etching by ). Therefore, it is presumed that the etching solution of this embodiment has improved etching selectivity of SiGe compounds for Si, Ge, and their oxides compared to fluorides such as hydrofluoric acid (HF) and ammonium fluoride (NH4F) that were used in conventional etching solutions.

[0050] (Manufacturing method for semiconductor devices) A method for manufacturing a semiconductor element according to a second aspect of the present invention is an etching method according to the first aspect. The method is characterized by including a step of etching a workpiece containing a SiGe compound using an etching solution.

[0051] Examples of substrates containing SiGe compounds include those described in "<Substrate>" under "(Etching Solution)" above, and substrates having a SiGe compound-containing layer are preferably exemplified. The method for forming the SiGe compound-containing layer on the substrate is not particularly limited, and known methods can be used. Examples of such methods include sputtering, chemical vapor deposition (CVD), molecular beam epitaxy (MBE), and atomic layer deposition (ALD). The raw materials for the SiGe compound-containing layer used when forming the SiGe compound-containing layer on the substrate are also not particularly limited and can be appropriately selected depending on the film formation method. The treated material may contain, in addition to the SiGe compound, at least one selected from the group consisting of Si, Ge, and oxides thereof, and preferably contains SiO2.

[0052] <Process of etching the object to be treated> This process involves etching a workpiece containing a SiGe compound using an etching solution according to the first embodiment described above, and includes the operation of bringing the etching solution into contact with the workpiece. The etching method is not particularly limited, and known etching methods can be used. Examples of such methods include, but are not limited to, spraying, immersion, and liquid-filling methods. In the spray method, for example, the workpiece is transported or rotated in a predetermined direction, and the etching solution according to the first embodiment is sprayed into the space, bringing the etching solution into contact with the workpiece. If necessary, the etching solution may be sprayed while rotating the substrate using a spin coater. In the immersion method, the workpiece is immersed in the etching solution according to the first embodiment described above, and the etching solution is brought into contact with the workpiece. In the liquid-filling method, the etching solution according to the first embodiment described above is applied to the workpiece, and the workpiece is brought into contact with the etching solution. These etching methods can be appropriately selected depending on the structure and material of the object to be treated. In the case of the spray method or the liquid-fill method, the amount of etching solution supplied to the object to be treated should be such that the surface of the object to be treated is sufficiently wetted with the etching solution.

[0053] The purpose of the etching process is not particularly limited and may be microfabrication of the surface of the workpiece containing a SiGe compound (for example, a SiGe compound-containing layer on a substrate), removal of SiGe compound-containing deposits adhering to the workpiece (for example, a substrate having a SiGe compound-containing layer), or cleaning of the surface of the workpiece containing a SiGe compound (for example, a SiGe compound-containing layer on a substrate). When the purpose of etching is to perform microfabrication on the surface of a workpiece containing SiGe compounds, the areas that should not be etched are usually covered with an etching mask before bringing the workpiece into contact with the etching solution. When the purpose of the etching process is to remove SiGe compound-containing deposits adhering to a workpiece, the etching solution according to the first embodiment described above can be brought into contact with the workpiece to dissolve the SiGe compound-containing deposits and remove them from the workpiece. When the purpose of the etching process is to clean the surface of the workpiece containing the SiGe compound, contacting the workpiece with the etching solution according to the first embodiment causes the surface to dissolve rapidly, and impurities such as particles adhering to the surface of the workpiece are removed from the surface in a short time.

[0054] The etching temperature is not particularly limited and should be any temperature at which the SiGe compound dissolves in the etching solution. For example, etching temperatures can range from 15 to 60°C. In all cases of spray, immersion, and liquid-filling methods, increasing the temperature of the etching solution increases the etching rate, but the processing temperature can be appropriately selected considering factors such as minimizing changes in the composition of the etching solution, workability, safety, and cost.

[0055] The etching time should be appropriately selected depending on the purpose of the etching process, the amount of SiGe compound to be removed by etching (e.g., the thickness of the SiGe compound-containing layer, the amount of SiGe compound deposits, etc.), and the etching conditions.

[0056] <Other processes> The semiconductor device manufacturing method of this embodiment may include other steps in addition to the etching process described above. The other steps are not particularly limited and include known steps performed when manufacturing semiconductor devices. Examples of such steps include, but are not limited to, steps for forming various structures such as metal wiring, gate structure, source structure, drain structure, insulating layer, ferromagnetic layer, and non-magnetic layer (layer formation, etching other than the etching process described above, chemical mechanical polishing, modification, etc.), resist film formation, exposure, development, heat treatment, cleaning, and inspection. These other steps can be performed as needed, either before or after the etching process.

[0057] According to the semiconductor device manufacturing method of this embodiment described above, the workpiece is etched using an etching solution according to the first embodiment, which contains hexafluorosilicic acid as a fluoride. The etching solution contains Si, Ge, and their oxides, with the general formula Si 1-x Ge xIt is possible to selectively etch the compound represented by (SiGe compound). Therefore, according to the semiconductor device manufacturing method of this embodiment, a semiconductor device in which the SiGe compound is selectively etched can be obtained without substantially affecting Si, Ge, and their oxides. [Examples]

[0058] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0059] <Preparation of Etching Solution (1)> (Examples 1-9, Comparative Examples 1-2) The etching solutions for each example were prepared by mixing the components shown in Table 1.

[0060] [Table 1]

[0061] In Table 1, each abbreviation has the following meaning. The numbers in brackets [ ] represent the amount (mass %) of the ingredient. H2SiF6: Hexafluoridated silica HF: Hydrofluoric acid NH4F: Ammonium fluoride HNO3: Nitric Acid Acetic acid (TOH)

[0062] <Etching process of the workpiece (1)> Si on the surface 0.75 Ge 0.25 A blanket substrate having the above layer was immersed in an etching solution at 25°C, and the etching rate was measured. The results are shown in Table 2.

[0063] <Etching process of the workpiece (2)> The SOI substrate was immersed in an etching solution at 25°C, and the etching rate was measured. The results are shown in Table 2.

[0064] <Etching process of the object to be treated (3)> A blanket substrate having an SiO2 layer on its surface was immersed in an etching solution at 25°C, and the etching rate was measured. The results are shown in Table 2.

[0065] [Table 2]

[0066] As shown in Table 2, the etching solutions of Examples 1 to 9 were found to have a higher SiGe etching selectivity compared to the etching solutions of Comparative Examples 1 to 2.

[0067] <Preparation of Etching Solution (2)> (Examples 10-13, Comparative Examples 3-4) The etching solutions for each example were prepared by mixing the components shown in Table 3.

[0068] [Table 3]

[0069] In Table 3, each abbreviation has the following meaning. The numbers in brackets [ ] represent the amount (mass %) of the ingredient. H2SiF6: Hexafluoridated silica HF: Hydrofluoric acid HNO3: Nitric Acid H3PO4: Phosphate

[0070] <Etching process of the workpiece (1)> Si on the surface 0.75 Ge 0.25 A blanket substrate having the above layer was immersed in an etching solution at 25°C, and the etching rate was measured. The results are shown in Table 4.

[0071] <Etching process of the workpiece (2)> The SOI substrate was immersed in an etching solution at 25°C, and the etching rate was measured. The results are shown in Table 4.

[0072] <Etching process of the object to be treated (3)> A blanket substrate having an SiO2 layer on its surface was immersed in an etching solution at 25°C, and the etching rate was measured. The results are shown in Table 4.

[0073] [Table 4]

[0074] The results shown in Table 4 confirm that the etching solutions of Examples 10-13 had a higher SiGe etching selectivity compared to the etching solutions of Comparative Examples 3-4.

Claims

1. For Si, Ge, and their oxides, the general formula is Si 1-x Ge x An etching solution for selectively etching a compound represented by the formula (where x is greater than 0 and less than 1), containing a fluoride and an oxidizing agent, the fluoride includes hexafluorosilicic acid; An etching solution having an etching rate A of 10 Å / min or more measured under the following conditions: (Measurement Condition A) Si on the surface 0.75 Ge 0.25 The blanket substrate having the layer is immersed in the etching solution at 25° C., and the etching rate is measured.

2. The etching solution according to claim 1, further comprising a polar organic solvent.

3. 3. The etching solution according to claim 1, further comprising phosphoric acid and / or a derivative thereof.

4. 4. The etching solution according to claim 1, wherein the oxidizing agent is nitric acid.

5. When the etching rate measured under the following conditions is defined as etching rate B, 5. The etching solution according to claim 1, wherein A / B is 10 or more. (B Measurement Conditions) A blanket substrate having a SiO2 layer on its surface is immersed in an etching solution at 25°C, and the etching rate is measured.

6. The etching solution according to any one of claims 1 to 5 is used to form a compound of the general formula Si 1-x Ge x A method for manufacturing a semiconductor device, comprising the step of etching an object to be treated, the object including a compound represented by the formula:

7. The method for manufacturing a semiconductor device according to claim 6, wherein the object further contains SiO2.