TW202136478A - Etching solution and method for manufacturing semiconductor element - Google Patents

Abstract

An etching solution for selectively performing an etching process on a compound represented by General Formula Si1-xGex, in which x is more than 0 and less than 1, with respect to Si, Ge, and oxides thereof, the etching solution including hydrofluoric acid, nitric acid, and water, in which a content ratio of the hydrofluoric acid in the entire etching solution is 0.002% by mass or more and 1.0% by mass or less, a content ratio of the nitric acid in the entire etching solution is 10% by mass or more, and a content ratio of the water in the entire etching solution is 40% by mass or less.

Description

Etching solution, and manufacturing method of semiconductor element

The present invention relates to an etching solution and a manufacturing method of semiconductor elements. This application claims priority based on Japanese Patent Application No. 2019-233655 filed in Japan on December 25, 2019 and Japanese Patent Application No. 2020-180113 filed on October 28, 2020, and the content is incorporated herein.

In the past, the scaling of the structure within the integrated circuit has made it possible to increase the density of the functional units on the semiconductor chip. For example, the shrinking of the size of the transistor can integrate more memory components on the chip, and it is related to the manufacturing of products with increased capacity.

In the manufacture of field-effect transistors (FET) used in integrated circuit devices, Ge is used as a semiconductor crystal material other than silicon. Ge has high charge carrier (hole) mobility, band gap shift, different lattice constants, and the ability to become an alloy with silicon and form a semiconductor binary alloy with SiGe. Compared with silicon depending on the situation Several advantageous features.

There have been many proposals for etching solutions with high selectivity for Ge materials (especially compounds _{represented by the general formula Si 1-x} Ge _x , but x is more than 0 and less than 1, sometimes referred to as "SiGe compounds" hereinafter). It is known that, for example, an etching solution containing hydrofluoric acid (DHF) and nitric acid is _{relatively high in etching of SiGe compounds compared to Si and SiO 2} (for example, refer to Patent Document 1).

On the other hand, if an etching solution containing hydrofluoric acid (DHF) and nitric acid selectively etches only SiGe in a multilayer structure made of Si/SiGe/Si, if the etching continues for a long time, the SiGe layer will be etched. Stop in the middle (that is, cause the so-called etch stop) defect. Therefore, when the SiGe is removed, the Si layer is etched unintentionally, and a stable shape cannot be obtained, which causes changes in the characteristics of the transistor, and further deteriorates the yield.

In order to solve the above-mentioned problem, the following method is proposed in Patent Document 1. (method 1) While rotating the substrate with the SiGe layer, spray the fluorine nitric acid solution for a short time of about tens of seconds to etch the SiGe layer. Then, the substrate is rotated and the spraying of the fluoronitric acid solution is temporarily stopped. After that, the substrate is rotated and the fluoronitric acid solution made from the new solution is sprayed again. (Method 2) The substrate provided with the SiGe layer is immersed in the fluoronitric acid solution stored in the etching tank, and the SiGe layer is wet-etched for a short time for about 1 minute. Next, it is taken out from the etching tank, and it is immersed in a water washing tank to perform a water washing step. After that, the substrate was again immersed in the fluoronitric acid solution stored in the etching tank, and wet etching was performed for a short time of about 1 minute. The etching process and the water washing process are repeated several times in this way. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2008-160073 A

[The problem to be solved by the invention]

However, since the method described in Patent Document 1 increases the number of steps in the manufacturing process, there is a problem that it is not practical in terms of production efficiency and manufacturing cost. The present invention was completed in view of the above circumstances, and its subject is to provide a _{compound represented by the general formula Si 1-x} Ge _x for selective etching of Si, Ge and these oxides, and which is difficult to cause etching to stop. Solution, and a method for manufacturing semiconductors using the etching solution. [Means to solve the problem]

In order to solve the above-mentioned problems, the present invention adopts the following configuration.

The first aspect of the present invention is an etching solution, which is used to selectively etch Si, Ge and oxides of these _{compounds represented by the general formula Si 1-x} Ge _x (but x exceeds 0 and does not The etching solution of 1), which contains hydrofluoric acid, nitric acid and water, the content of hydrofluoric acid in the entire etching solution is 0.002% by mass to 1.0% by mass, and the content of nitric acid in the entire etching solution is 10% by mass or more, and the water content in the entire etching solution is 40% by mass or less.

The second aspect of the present invention is a method of manufacturing a semiconductor device, which includes the step of using the aforementioned etching solution to etch a processed body containing a compound represented _{by the general formula Si 1-x} Ge _x. [Effects of the invention]

_{According to the etching solution of the present invention, the compound represented by the general formula Si 1-x} Ge _x can be selectively etched for Si, Ge, and these oxides, and at the same time, the etching stop can be suppressed. Furthermore, according to the semiconductor manufacturing method of the present invention, it is possible to manufacture a semiconductor in which a compound _{represented by the general formula Si 1-x} Ge _x is selectively etched for Si, Ge, and oxides thereof.

(Etching solution)

The etching solution of the first aspect of the present invention includes hydrofluoric acid, nitric acid, and water. The etching solution of this aspect is used for the selective etching treatment of Si, Ge, and these oxides _{. The compound represented by the general formula Si 1-x} Ge _x (however, x is more than 0 and less than 1) (hereinafter sometimes Just called "SiGe compound").

＜Hydrofluoric acid＞ The etching solution of this embodiment contains hydrofluoric acid (DHF). The content of hydrofluoric acid in the entire etching solution is 0.002% by mass to 1.0% by mass, preferably 0.005% by mass to 0.9% by mass, more preferably 0.001% by mass to 0.8% by mass, and still more preferably 0.01% by mass % Or more and 0.7 mass% or less, particularly preferably 0.02 mass% or more and 0.6 mass% or less. If the content of hydrofluoric acid is within the aforementioned range, the etching rate for the SiGe compound is increased.

<Nitric acid> The etching solution of this embodiment contains nitric acid (HNO ₃ ). The nitric acid content of the entire etching solution is 10% by mass or more, preferably 10% by mass or more and 55% by mass or less, more preferably 11% by mass or more and 55% by mass or less, and still more preferably 12% by mass or more and 54% by mass or less . Particularly preferred is 15% by mass or more and 54% by mass or less. If the content of nitric acid is within the aforementioned range, it becomes easy to oxidize the SiGe compound, and the etching rate to the SiGe compound is increased.

＜Water＞ The etching solution of this embodiment contains water. Water may also contain trace components that are unavoidably mixed. The water used in the etching solution of this embodiment is preferably purified water such as distilled water, ion exchange water, and ultrapure water, and more preferably ultrapure water generally used in semiconductor manufacturing. The water content in the entire etching solution is 40% by mass or less, preferably 5% by mass or more and 40% by mass or less, more preferably 6% by mass or more and 38% by mass or less, and still more preferably 7% by mass or more and 36% by mass or less , Particularly preferably 8% by mass or more and 35% by mass or less. If the water content is within the aforementioned range, the etching rate of SiGe can be controlled.

＜Other ingredients＞ The etching solution of this embodiment may contain other components in addition to the above-mentioned components within a range that does not impair the effects of the present invention. Examples of other components include solvents, phosphoric acid and/or derivatives thereof, pH adjusters, deactivators, surfactants, and the like.

・Solvent The etching solution of this embodiment can be prepared by mixing hydrofluoric acid, nitric acid, water, and other optional components in a solvent. The solvent is not particularly limited, and examples include polar organic solvents and the like.

・Polar organic solvent The etching solution of this embodiment may contain a polar organic solvent within a range that does not impair the effect of the present invention. Examples of polar organic solvents include organic carboxylic acid solvents (such as acetic acid, formic acid, etc.), alcohol solvents (such as methanol, ethanol, ethylene glycol, propylene glycol, glycerol, 1,3-propanediol, 1,3-butanediol) , 1,4-butanediol, diethylene glycol, dipropylene glycol, furfuryl alcohol and 2-methyl-2,4-pentanediol, etc.), dimethyl sulfide, ether solvents (such as ethylene glycol dimethyl Ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, propylene glycol dimethyl ether) and the like. Among them, as the polar organic solvent, an organic carboxylic acid solvent is preferred, and acetic acid is more preferred.

In the etching solution of this embodiment, a polar organic solvent may be used individually by 1 type, and may use 2 or more types together. When the etching solution of this embodiment contains a polar organic solvent, the content of the polar organic solvent is, for example, 10 to 90% by mass relative to the total mass of the etching solution, preferably 11 to 85% by mass, and more preferably 12 to 80 quality%.

・Phosphoric acid and/or its derivatives The etching solution of this embodiment may contain phosphoric acid and/or its derivatives as a solvent within a range that does not impair the effects of the present invention. Examples of phosphoric acid and/or derivatives thereof include compounds represented by the following general formula (1).

[式中，各R分別獨立為氫原子或碳數1~20之烷基]。

[In the formula, each R is independently a hydrogen atom or an alkyl group having 1 to 20 carbons].

In the aforementioned formula (1), examples of the alkyl group having 1 to 20 carbon atoms in R include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, Undecyl, dodecyl, tridecyl, isotridecyl, tetradecyl, pentadecyl, hexadecyl, isohexadecyl, heptadecyl, octadecyl Alkyl, nonadecyl, eicosyl, isomers of the above-mentioned alkyl groups, etc. Among them, as R, a hydrogen atom or an alkyl group having 1 to 20 carbon atoms is preferred, and a hydrogen atom is more preferred.

In the etching solution of the present embodiment, phosphoric acid and/or its derivatives may be used singly, or two or more of them may be used in combination. When the etching solution of this embodiment contains phosphoric acid and/or its derivatives, the content of phosphoric acid and/or its derivatives is, for example, 1-40% by mass relative to the total mass of the etching solution, preferably 2~38% by mass %, more preferably 3 to 37% by mass, particularly preferably 5 to 35% by mass.

・PH adjuster In order to further increase the etching rate of SiGe compounds, the etching solution of this embodiment may also contain a pH adjuster The pH adjuster is preferably at least one selected from the group consisting of acids and their salts. Specifically, examples include 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, acetone 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 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 Acetic acid, hydrobromic acid (62% by weight), sulfuric acid, ammonium acetate, sodium acetate, potassium acetate, tetramethylammonium acetate and other tetraalkylammonium acetates, phosphonium acetate, ammonium butyrate, ammonium trifluoroacetate, ammonium carbonate, Ammonium chloride, ammonium sulfate, phosphoric acid, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, double hydrogen phosphate (tetramethyl ammonium), disodium hydrogen phosphate, sodium dihydrogen phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, phosphoric acid Di-tetraalkylammonium hydrogen, di-tetraalkylammonium dihydrogen phosphate, diphosphonium hydrogen phosphate, phosphonium dihydrogen phosphate, ammonium phosphonate, tetraalkylammonium phosphonate, sodium phosphonate, potassium phosphonate, phosphonium phosphonate , Hydroxyethylene diphosphonic acid, these salts, etc. Among them, ammonium acetate or ammonium sulfate is preferred.

In addition, the etching solution of this embodiment may contain a basic compound as a pH adjuster. As the basic compounds, organic basic compounds and inorganic basic compounds can be used. Examples of organic basic compounds include quaternary ammonium salts represented by organic quaternary ammonium hydroxide, trimethylamine and triethylamine, etc. Salts of amines and their derivatives are suitable examples. In addition, examples of inorganic basic 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.

In the etching solution of the present embodiment, the pH adjusting agent may be used singly, or two or more of them may be used in combination. When the etching solution of this embodiment contains a pH adjuster, the content of the pH adjuster is exemplified as 0.01-10% by mass relative to the total mass of the etching solution, preferably 0.02-4.5% by mass, more preferably 0.03-4% by mass %, more preferably 0.05 to 3% by mass. If the content of the pH adjuster is within the aforementioned range, it is easier to increase the etching rate to the SiGe compound.

・Passivating agent The etching solution of this embodiment may contain a passivating agent for germanium. Examples of passivating agents include ascorbic acid, L(+)-ascorbic acid, erythorbic acid, ascorbic acid derivatives, boric acid, ammonium diborate, borates (such as ammonium pentaborate, sodium tetraborate and ammonium diborate), alanine, arginine , Aspartic acid, aspartic acid, cysteine, glutamic acid, glutamic acid, histidine, isoleucine, leucine, lysine, methionine, phenylalanine , Proline, serine, threonine, tryptophan, tyrosine, valine, sodium bromide, potassium bromide, rubidium bromide, magnesium bromide, calcium bromide, with formula NR ¹ R ² R ³ R ⁴ Br (wherein, R ¹ , R ² , R ³ and R ⁴ may be the same or different, and are selected from hydrogen and branched or straight chain C ₁ -C ₆ alkyl groups (such as methyl , Ethyl, propyl, butyl, pentyl, hexyl) ammonium bromide.

In the etching solution of this embodiment, the passivation agent may be used individually by 1 type, and may use 2 or more types together. When the etching solution of this embodiment contains a passivating agent, for example, relative to the total mass of the etching solution, it is preferably 0.01 to 5% by mass, and more preferably 0.1 to 1% by mass.

・Surfactant The etching solution of this embodiment may contain a surfactant for the purpose of adjusting the wettability of the etching solution to the object to be processed. As the surfactant, a nonionic surfactant, an anionic surfactant, a cationic surfactant, or an amphoteric surfactant can be used, and these can also be used in combination.

As nonionic surfactants, for example, polyalkylene oxide alkyl phenyl ether-based surfactants, polyalkylene oxide alkyl ether-based surfactants, and those made of polyethylene oxide and polypropylene oxide Block polymerization surfactants, polyalkylene oxide stilbene phenyl ether surfactants, polyalkylene tribenzyl phenyl ether surfactants, acetylene polyalkylene oxide surfactants, etc.

As an anionic surfactant, for example, alkyl sulfonic acid, alkyl benzene sulfonic acid, alkyl naphthalene sulfonic acid, alkyl diphenyl ether sulfonic acid, fatty acid amide sulfonic acid, polyoxyethylene alkyl ether carboxylic acid, Polyoxyethylene alkyl ether acetic acid, polyoxyethylene alkyl ether propionic acid, alkyl phosphonic acid, fatty acid salt, etc. Examples of the "salt" include ammonium salt, sodium salt, potassium salt, and tetramethylammonium salt.

Examples of the cationic surfactant include, for example, a quaternary ammonium salt-based surfactant, or an alkylpyridinium-based surfactant.

As the amphoteric surfactant, for example, betaine type surfactants, amino acid type surfactants, imidazoline type surfactants, amine oxide type surfactants, etc. are exemplified.

These surfactants are generally commercially available. Surfactant can be used individually by 1 type. Two or more types can also be used in combination.

＜Processed body＞ The etching solution of this embodiment is used to etch SiGe compounds, and the object to be processed containing the SiGe compound is used as an etching target. The object to be processed is not particularly limited as long as it contains a SiGe compound. Examples include a substrate having a SiGe compound-containing layer (SiGe compound-containing film). The aforementioned substrates are not particularly limited, and examples include semiconductor wafers, glass substrates for photomasks, glass substrates for liquid crystal displays, glass substrates for plasma display, substrates for FED (Field Emission Display), substrates for optical discs, and magnetic disks. Various substrates such as substrates and substrates for optical magnetic disks. As the aforementioned substrate, a substrate for manufacturing a semiconductor device is preferably used. In addition to the SiGe compound layer and the base material of the substrate, the aforementioned substrates can also have various layers and structures, such as metal wiring, gate structure, source structure, drain structure, insulating layer, ferromagnetic layer, and non-magnetic layer, etc. . In addition, the uppermost layer of the device surface of the substrate does not necessarily have to be a SiGe compound-containing layer. For example, the middle layer of a multilayer structure may be a SiGe compound-containing layer. The size, thickness, shape, layer structure, etc. of the substrate are not particularly limited, and can be appropriately selected according to the purpose.

The aforementioned SiGe compound-containing layer is preferably a SiGe compound-containing layer, 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 according to the purpose. The thickness of the SiGe compound layer is, for example, in the range of 1 to 200 nm and 1 to 20 nm.

The aforementioned object to be processed may contain at least one selected from the group consisting of Si, Ge, and oxides other than SiGe compounds, and preferably contains SiO ₂ .

The etching solution of this embodiment can also be used for the micro-processing of the SiGe-containing compound layer in the substrate, can also be used to remove the SiGe-containing compound adherents attached to the substrate, and can also be used for substrates with SiGe-containing compound layers on the surface. The treatment body removes impurities such as particles.

如上述式(1)所示，若使用含有氫氟酸及硝酸之蝕刻液長時間蝕刻SiGe化合物，則因硝酸及亞硝酸對Ge之氧化速度較Si快，故蝕刻中之最表面之Ge濃度下降，並導致SiGe層之蝕刻中途停止，亦即有引起所謂蝕刻終止之虞。 然而，本實施形態之蝕刻液，推測因將氫氟酸、硝酸及水之含量設為特定範圍內，故Si及Ge之氧化速度相等，而抑制SiGe化合物之蝕刻終止之同時，可選擇性蝕刻SiGe化合物。According to the etching solution of this embodiment described above, since it contains a certain amount of hydrofluoric acid, nitric acid and water, it can be selectively etched for Si, Ge and these oxides by the general formula Si _1-x Ge _x The compound (SiGe compound), and can inhibit the etching stop of SiGe compound. Although the reason is uncertain, it is estimated as follows. When the etching solution of this embodiment is in contact with the object to be processed containing the SiGe compound, the SiGe compound can be oxidized by nitric acid. Compound oxide of SiGe by fluoride ions of hydrofluoric acid (F ^-) is etched. Specifically, SiGe is removed by the electrochemical reaction of the following formula (1).

As shown in the above formula (1), if an etching solution containing hydrofluoric acid and nitric acid is used to etch the SiGe compound for a long time, the oxidation rate of Ge by nitric acid and nitrous acid is faster than that of Si, so the Ge concentration on the top surface during etching Decrease, and cause the etching of the SiGe layer to stop in the middle, that is, it may cause the so-called etching stop. However, the etching solution of this embodiment presumably sets the content of hydrofluoric acid, nitric acid, and water within a specific range, so that the oxidation rates of Si and Ge are equal, and the etching stop of the SiGe compound is suppressed while selective etching is possible. SiGe compound.

(Method of manufacturing semiconductor components) The manufacturing method of the semiconductor device of the second aspect of the present invention is characterized by including the step of using the etching solution of the first aspect described above to etch the processed body containing the SiGe compound.

As the object to be processed containing the SiGe compound, an example is the same as that described in the "<object to be processed>" in the above-mentioned "(etching solution)", and a preferable example is a substrate having a SiGe compound-containing layer. The method of forming the SiGe-containing compound layer on the substrate is not particularly limited, and conventional methods can be used. Examples of this method include a sputtering method, a chemical vapor deposition (CVD: Chemical Vapor Deposition) method, an epitaxial growth method, and an atomic layer deposition (ALD: Atomic layer deposition) method. The raw material of the SiGe-containing compound layer used when forming the SiGe-containing compound layer on the substrate is also not particularly limited, and can be appropriately selected according to the film forming method. The aforementioned object to be processed may contain at least one selected from the group consisting of Si, Ge, and oxides other than SiGe compounds, and preferably contains SiO ₂ .

＜Steps for etching the treated body＞ This step is a step of using the etching solution of the first aspect described above to etch an object to be processed containing a SiGe compound, and includes the operation of bringing the etching solution into contact with the object to be processed. The etching method is not particularly limited, and conventional etching methods can be used. As the method, for example, a spray method, a dipping method, a liquid coating method, etc. are exemplified, but it is not limited to these. In the spray method, for example, the object to be processed is transported or rotated in a specific direction, and the etching liquid of the first aspect is sprayed into the space to bring the etching liquid into contact with the object to be processed. According to requirements, a spin coater can be used to spray the aforementioned etching solution while rotating the substrate. The immersion method is to immerse the object to be processed in the etching solution of the first aspect described above, and bring the etching solution into contact with the object to be processed. In the liquid coating method, the etching liquid of the first aspect is overflowed on the object to be processed, and the object to be processed is brought into contact with the etching liquid. These etching treatment methods can be appropriately selected according to the structure and material of the object to be processed. In the case of the spray method or the liquid coating method, the supply amount of the aforementioned etching solution to the object to be treated may be such that the treated surface of the object to be treated can be sufficiently wetted by the aforementioned etching solution.

The purpose of the etching treatment is not particularly limited. It can be the microfabrication of the processed surface of the processed body containing SiGe compound (for example, the SiGe compound-containing layer on the substrate), or it may be attached to the processed body (for example, it has a SiGe compound-containing layer). The removal of the SiGe compound-containing attachment of the compound layer substrate can also be the cleaning of the processed surface (for example, the SiGe compound-containing layer on the substrate) of the processed body containing the SiGe compound.

The temperature for performing the etching treatment is not particularly limited, as long as the temperature can dissolve the SiGe compound in the aforementioned etching solution. As the temperature of the etching treatment, for example, 15 to 60°C. In any of the spray method, dipping method, and liquid coating method, the etching rate can be increased by increasing the temperature of the etching solution, but it is considered that the composition change of the etching solution is suppressed to be small, workability, safety, cost, etc. , The treatment temperature can also be selected appropriately.

The time for the etching treatment can be appropriately selected according to the purpose of the etching treatment, the amount of SiGe compound removed by etching (for example, the thickness of the SiGe compound-containing layer, the amount of SiGe compound deposits, etc.), and the etching treatment conditions. .

＜Other steps＞ The manufacturing method of the semiconductor device of this embodiment may include other steps in addition to the above-mentioned etching treatment step. Other steps are not particularly limited, and examples are conventional steps performed when manufacturing semiconductor devices. Examples of this step include the formation of various structures such as channel formation, High-K/metal gate formation, metal wiring, gate structure, source structure, drain structure, insulating layer, ferromagnetic layer, and non-magnetic layer. (Layer formation, etching, chemical mechanical polishing, deformation, etc. other than the above-mentioned etching process), resist film formation step, exposure step, development step, heat treatment step, cleaning step, inspection step, etc., but not limited to this. These other steps can be appropriately performed before or after the above-mentioned etching treatment step according to requirements.

According to the manufacturing method of the semiconductor device of the present embodiment described above, the etching treatment of the object to be processed is performed using the etching solution of the first aspect that contains a specific amount of hydrofluoric acid, nitric acid, and water. _{The etching solution selectively etches the compound represented by the general formula Si 1-x} Ge _x (SiGe compound) for Si, Ge and these oxides, and can inhibit the etching termination of the SiGe compound. Therefore, according to the semiconductor device manufacturing method of this embodiment, a semiconductor device in which Si, Ge, and these oxides are substantially unaffected, and the SiGe compound is selectively etched can be obtained. In addition, according to the semiconductor device manufacturing method of this embodiment, since the etching stop of the SiGe compound is suppressed, the SiGe compound can be selectively etched for a longer time (for example, more than 3 minutes) than in the past. Therefore, the manufacturing method of the semiconductor device of the present embodiment does not require complicated etching steps, which not only improves the uniformity of etching in the plane, but also shortens the processing time and reduces the cost, and has high practicability. [Example]

Hereinafter, the present invention will be described in further detail with examples, but the present invention is not limited to these examples.

＜Preparation of etching solution (1)＞ (Examples 1 to 6, Comparative Examples 1 to 6) The components shown in Table 1 were mixed to prepare the etching solutions of each example.

In Table 1, each abbreviation has the following meanings. DHF: Hydrofluoric acid HNO ₃ : Nitric acid AcOH: Acetic acid DIW: Water

＜Etching treatment of the object to be treated (1)＞ A SiGe film is epitaxially grown on a silicon substrate to obtain a processed body (1) on which the SiGe film is formed. A test piece was cut from the obtained object (1), and the thickness of the SiGe film was measured by fluorescent X-ray analysis. The film thickness was 50 nm. The etching solution of each example was poured into a beaker, and the aforementioned test piece was immersed in the etching solution of each example at room temperature (23° C.) for 5 minutes to perform etching treatment. After the aforementioned etching treatment, the test piece was dried by blowing nitrogen gas, and the thickness of the SiGe film was measured by fluorescent X-ray analysis. According to the film thickness of the SiGe film before and after the etching process, the etching rate (nm/min) for SiGe is calculated. The results are shown in Table 2.

＜Etching treatment of the object to be treated (2)＞ A silicon oxide film is formed by thermal oxidation on a silicon substrate to obtain a processed body (2). A test piece was cut out from the processed body (2), and the film thickness of the silicon oxide film was measured by a spectroscopic ellipsometer. The film thickness was 100 nm. The etching solution of each example was poured into a beaker, and the aforementioned test piece was immersed in the etching solution of each example at room temperature (23° C.) for 5 minutes to perform etching treatment. After the aforementioned etching treatment, the test piece was dried by blowing nitrogen gas, and the thickness of the silicon oxide film was measured by a spectroscopic ellipsometer. According to the film thickness of the silicon oxide film before and after the etching process, the etching rate (nm/min) for Si is calculated. The results are shown in Table 2.

＜Etching treatment of the object to be treated (3)＞ A test piece was cut out from the SOI (100) substrate to obtain a processed body (3). The obtained object to be processed (3) was used to measure the thickness of the Si film with a spectroscopic ellipsometer, and the film thickness was 100 nm. The etching solution of each example was poured into a beaker, and the aforementioned test piece was immersed in the etching solution of each example at room temperature (23° C.) for 5 minutes to perform etching treatment. After the aforementioned etching treatment, the test piece was dried by blowing nitrogen gas, and the thickness of the Si film was measured by a spectroscopic ellipsometer. According to the film thickness of the Si film before and after the etching process, the etching rate (nm/min) for Si is calculated. The results are shown in Table 2.

＜Evaluation of etching selection ratio (1)＞ Calculate the object to be processed based on the results of the etching rate obtained from the above-mentioned "etching treatment of the object to be processed (1)", "etching treatment of the object to be processed (2)", and "etching treatment of the object to be processed (3)" ( 1)/The etching selection ratio of the processed body (2) and the etching selection ratio of the processed body (1)/the processed body (3). The results are shown in Table 2.

＜Evaluation of etching termination (1)＞ In the above "etching treatment (1) of the object to be processed", corresponding to the obtained SiGe etching rate (nm/min), calculate the etching rate for SiGe (nm/min) when the etching treatment time is changed to the following: It is evaluated based on the following criteria. ・SiGe etching rate is 10nm/min or less The etching treatment time of 1 minute, 3 minutes, and 5 minutes was compared and evaluated based on the following evaluation criteria. A: The variation rate of the etching rate for SiGe (nm/min) after 1 minute etching treatment and the etching rate for SiGe after 5 minutes etching treatment is within 20% B: The variation rate of the etching rate for SiGe (nm/min) after 1 minute etching treatment and the etching rate for SiGe after 5 minutes etching treatment exceeds 20% C: The etching rate for SiGe after 5 minutes of etching treatment is below 0.6nm/min ・SiGe etching rate exceeds 10nm/min and 20nm/min or less The etching processing time of 30 seconds, 90 seconds, and 150 seconds was compared, and evaluated based on the following evaluation criteria. A: The variation rate of the etching rate for SiGe (nm/min) after 30 seconds of etching treatment and the etching rate for SiGe after 150 seconds of etching treatment is within 20% B: The variation rate of the etching rate for SiGe (nm/min) after 30 seconds of etching treatment and the etching rate for SiGe after 150 seconds of etching treatment exceeds 20% C: The etching rate for SiGe after 5 minutes of etching treatment is below 0.6nm/min ・SiGe etching rate exceeds 20nm/min and below 50nm/min The etching processing time of 20 seconds, 40 seconds, and 60 seconds was compared, and evaluated based on the following evaluation criteria. A: The variation rate of the etching rate for SiGe (nm/min) after 20 seconds of etching rate treatment and the etching rate for SiGe after 60 seconds of etching treatment is within 20% B: The variation rate of the etching rate for SiGe (nm/min) after 20 seconds of etching rate treatment and the etching rate for SiGe after 60 seconds of etching treatment exceeds 20% C: The etching rate for SiGe after 5 minutes of etching treatment is below 0.6nm/min

From the results shown in Table 2, comparing the etching solutions of Examples 1 to 6 with the etching solutions of Comparative Examples 1 to 6, it is confirmed that the SiGe etching selection is relatively high and the etching termination of SiGe is suppressed.

(Examples 7-10, Comparative Example 7) The components shown in Table 3 were mixed to prepare the etching solutions of each example.

In Table 3, each abbreviation has the following meaning. DHF: Hydrofluoric acid HNO ₃ : Nitric acid AcOH: Acetic acid H ₃ PO ₄ : Phosphoric acid DIW: Water

＜Etching treatment of the object to be treated (4)＞ Except that the etching solutions of Comparative Example 7 and Examples 7 to 10 were used, the etching rate (nm/min) of SiGe was calculated in the same manner as in the above-mentioned "Etching Treatment of Object to be Processed (1)". The results are shown in Table 4.

＜Etching treatment of the object to be treated (5)＞ Except that the etching solutions of Comparative Example 7 and Examples 7 to 10 were used, the etching rate (nm/min) of Si was calculated in the same manner as in the above-mentioned "Etching treatment of the object to be processed (2)". The results are shown in Table 4.

＜Etching treatment of the object to be treated (6)＞ Except that the etching solutions of Comparative Example 7 and Examples 7 to 10 were used, the etching rate (nm/min) of Si was calculated in the same manner as in the above-mentioned "Etching treatment of the object to be processed (3)". The results are shown in Table 4. ＜Evaluation of etching selection ratio (2)＞ Calculate the object to be processed ( 4)/The etching selection ratio of the processed body (5) and the etching selection ratio of the processed body (4)/the processed body (6). The results are shown in Table 4.

＜Evaluation of etching termination (2)＞ In the above "Etching treatment of the object to be processed (4)", corresponding to the obtained SiGe etching rate (nm/min), the same as the above "<Etching termination evaluation (1)>" is calculated when the etching treatment time is changed. The etching rate (nm/min) of SiGe was evaluated based on the same criteria as the above-mentioned "<Evaluation of Etching Termination (1)>". The results are shown in Table 4.

From the results shown in Table 4, comparing the etching solutions of Examples 7 to 10 and the etching solution of Comparative Example 7, it is confirmed that the SiGe etching selection is relatively high, and the etching termination of SiGe can be suppressed.

The preferred embodiments of the present invention are described above, but the present invention is not limited to these embodiments. Without departing from the scope of the gist of the present invention, additions, omissions, substitutions, and other changes to the configuration can be made. The present invention is not limited to the foregoing description, but is only limited by the scope of the attached patent application.

Claims (7)

An etching solution, which is used to selectively etch a compound _{represented by the general formula Si 1-x} Ge _x (but x exceeds 0 and does not reach 1), and includes hydrofluoric acid, nitric acid and water. The aforementioned etching The content of hydrofluoric acid in the entire solution is 0.002% by mass to 1.0% by mass, the content of nitric acid in the entire etching solution is 10% by mass or more, and the water content in the entire etching solution is 40% by mass the following. Such as the etching solution of claim 1, which further contains a polar organic solvent. The etching solution of claim 2, wherein the aforementioned polar organic solvent is acetic acid. The etching solution according to claim 1, wherein the content of the nitric acid in the entire etching solution is 55% by mass or less. The etching solution of claim 1, wherein the water content in the entire etching solution is 5% by mass or more. The etching solution of claim 1, which further contains phosphoric acid and/or its derivatives. A method for manufacturing a semiconductor device, which includes using the etching solution as claimed in any one of claims 1 to 6, and etching a processed body including a compound represented _{by the general formula Si 1-x} Ge _x.