Semiconductor processing solution and method for using the solution as a low-toxicity semiconductor processing solution

Abstract

A semiconductor processing solution comprising the following (A) to (E): (A) A quaternary ammonium ion represented by the following formula (1): (B) Halide ions (C) Hydroxide ion (D) Oxidizing agent (E)Water TIFF0007663793000009.tif41170 (In the formula, R 1 , R 2 , R 3 , and R 4 are each independently an alkyl group having 1 to 16 carbon atoms, provided that R 1 , R 2 , R 3 , and R 4 Among these, at least one alkyl group has 2 to 16 carbon atoms.)

Description

[Technical field]

[0001] The present invention relates to a semiconductor processing liquid and a method for using the same as a low-toxicity semiconductor processing liquid, and more particularly to a semiconductor processing liquid containing a specific quaternary ammonium ion, a halide ion, a hydroxide ion, an oxidizing agent, and water. [Background technology]

[0002] Quaternary ammonium compounds are used as phase transfer catalysts, surfactants, disinfectants, etc. Among quaternary ammonium compounds, tetramethylammonium hydroxide in particular is used as a type of organic alkali that exhibits strong basicity in semiconductor processing solutions used for cleaning, etching, developing solutions, etc. during semiconductor manufacturing.

[0003] For example, Patent Document 1 discloses a ruthenium semiconductor processing solution containing hypobromite ions. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2021 / 059666 Summary of the Invention [Problem to be solved by the invention]

[0005] In the examples of Patent Document 1, a semiconductor processing solution for ruthenium using tetramethylammonium hydroxide as a base compound is disclosed. However, the present inventors have noticed that an aqueous solution of tetramethylammonium hydroxide (hereinafter also referred to as TMAH) is highly toxic and requires careful handling. In addition, a semiconductor processing solution containing an oxidizing agent can remove or process transition metals by oxidizing and dissolving (etching) the transition metals with the oxidizing agent, but it has been found that surface roughness after etching is a problem. Therefore, an object of the present invention is to provide a semiconductor processing liquid that can suppress surface roughness after etching and has low toxicity, and to provide a method for using the low-toxicity semiconductor processing liquid. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to obtain a low-toxicity semiconductor processing solution, and as a result, have found that a semiconductor processing solution containing a specific quaternary ammonium ion, a halide ion, a hydroxide ion, an oxidizing agent, and water is low-toxic and capable of suppressing surface roughness after etching, thereby completing the present invention.

[0007] That is, the present invention is configured as follows. Item 1: A semiconductor processing solution comprising the following (A) to (E): (A) A quaternary ammonium ion represented by the following formula (1): (B) Halide ions (C) Hydroxide ion (D) Oxidizing agent (E)Water [ka] (In the formula, R 1 , R 2 , R 3 , and R 4 are each independently an alkyl group having 1 to 16 carbon atoms, provided that R 1 , R 2 , R 3 , and R 4 Among these, at least one alkyl group has 2 to 16 carbon atoms.) Item 2 R in the above formula (1) 1 , R 2 , R 3 , and R 4 Item 2. The semiconductor processing solution according to item 1, wherein not all of the alkyl groups are the same. Item 3 R in the formula (1) 1 , R 2 , and R 3is a methyl group, and R 4 3. The semiconductor processing solution according to item 1 or 2, wherein is an alkyl group having 2 to 16 carbon atoms. Item 4. The semiconductor processing solution according to any one of Items 1 to 3, wherein the (B) halide ion is a chloride ion or a bromide ion. Item 5. The semiconductor processing solution according to any one of Items 1 to 4, wherein the concentration of the halide ions in the semiconductor processing solution is 0.1 ppm by mass to 5.0% by mass. Item 6. The semiconductor processing solution according to any one of Items 1 to 5, wherein an LD50 value calculated based on 100 mass% of the hydroxide of the quaternary ammonium ion in a toxicity test using rats based on OECD TG420 acute oral toxicity test exceeds 50 mg / kg. Item 7. The semiconductor processing solution according to any one of Items 1 to 6, wherein the oxidizing agent contains at least one halogen oxygen acid ion selected from the group consisting of hypochlorite ion, hypobromite ion, and periodate ion. Item 8. The semiconductor processing solution according to any one of Items 1 to 7, further comprising one or more compounds selected from the group consisting of alcohols and amines. Item 9. A method for using the semiconductor processing liquid according to any one of items 1 to 8 as a low-toxicity semiconductor processing liquid. Effect of the Invention

[0008] According to the present invention, a low-toxicity semiconductor processing solution is provided. As a result, a semiconductor processing solution that is highly safe during use and leads to a low environmental impact is provided. Also, a method for using the low-toxicity semiconductor processing solution is provided. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is an explanatory diagram showing an electrolytic cell. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described in detail below with reference to the preferred embodiments thereof, but the present invention is not limited to these embodiments as long as they do not depart from the gist of the present invention. In addition, the present invention can be modified and carried out as desired without departing from the gist of the present invention.

[0011] In this specification, a numerical range expressed using "~" means a range including the numerical values ​​before and after "~" as the lower and upper limits, and "A~B" means A or more and B or less. Furthermore, when a numerical range is expressed in stages, the upper and lower limits of each numerical range can be arbitrarily combined.

[0012] The semiconductor processing solution of the present invention contains the following (A) to (E): (A) A quaternary ammonium ion represented by the following formula (1): (B) Halide ions (C) Hydroxide ion (D) Oxidizing agent (E)Water [ka] (In the formula, R 1 , R 2 , R 3 , and R 4 are each independently an alkyl group having 1 to 16 carbon atoms (preferably 1 to 8, more preferably 1 to 4), provided that R 1 , R 2 , R 3 , and R 4 Among these, one or more alkyl groups have 2 to 16 carbon atoms (preferably 2 to 8, more preferably 2 to 4).

[0013] By including the quaternary ammonium ion represented by the above formula (1), the semiconductor processing solution tends to be less toxic than a semiconductor processing solution that uses tetramethylammonium hydroxide. Furthermore, by containing the quaternary ammonium ion represented by the above formula (1), the etching rate can be improved. Furthermore, roughness of the metal surface after etching can be suppressed.1 ~R 4 If the number of carbon atoms in R exceeds the above range, the steric hindrance of the quaternary ammonium ion becomes large, and the etching rate may decrease. 1 ~R 4 If the number of carbon atoms exceeds the above range, the quaternary ammonium halide described below becomes difficult to dissolve, which may make it difficult to produce a semiconductor processing liquid.

[0014] In the formula (1), R 1 , R 2 , R 3 , and R 4 It is also preferable that not all of are the same alkyl group. In other words, the compounds shown in the following (1) to (3) are preferable. (1)R 1 , R 2 , R 3 , and R 4 A compound in which any three of the above are the same alkyl group and the remaining one is a different alkyl group from the above. (2)R 1 , R 2 , R 3 , and R 4 any two of the above are the same alkyl group and the remaining two are different alkyl groups (the remaining two may be the same or different). (3)R 1 , R 2 , R 3 , and R 4 are all different alkyl groups. In the case of (1) above, R 1 , R 2 , R 3 , and R 4 and the remaining one is an alkyl group having 1 to 16 carbon atoms, the first three and the remaining one are different alkyl groups, and either the first three or the remaining one has a carbon number of 2 to 16. 1 , R 2 , R 3 , and R 4Among these, it is preferable that three of them are the same group and the remaining one is an alkyl group having 2 to 16 carbon atoms different from the above groups. In this case, the compound represented by formula (1) has two types of alkyl groups. In this embodiment, R 1 , R 2 , R 3 , and R 4 and the remaining alkyl group has 2 to 16 carbon atoms. Among these, the compound in which the remaining alkyl group has 2 to 8 carbon atoms is more preferable, and the compound in which the remaining alkyl group has 2, 3 or 4 carbon atoms is even more preferable. In the case of (2) above, R 1 , R 2 , R 3 , and R 4 and the remaining two are alkyl groups having 1 to 16 carbon atoms different from the first two, and the remaining two are the same or different alkyl groups, and either the first two or the remaining two have a carbon number of 2 to 16. In this case, the compound represented by formula (1) has two or three types of alkyl groups. In the case of (3) above, R 1 , R 2 , R 3 , and R 4 are all different alkyl groups, at least one of which has a carbon number of 2 to 16. In this case, the compound represented by formula (1) has four types of alkyl groups.

[0015] In addition, in the formula (1), R 1 , R 2 , R 3 , and R 4 may all be the same alkyl group. For example, R 1 , R 2 , R 3 , and R 4 may all be ethyl, propyl, or butyl.

[0016] Specific examples of the quaternary ammonium ion represented by the above formula (1) include tetraethylammonium ion, tetrapropylammonium ion, tetrabutylammonium ion, ethyltrimethylammonium ion, diethyldimethylammonium ion, triethylmethylammonium ion, propyltrimethylammonium ion, butyltrimethylammonium ion, etc. These quaternary ammonium ions may be used alone or in combination.

[0017] The semiconductor processing liquid contains hydroxide ions. The fact that the semiconductor processing liquid contains quaternary ammonium ions represented by the above formula (1) and hydroxide ions can also be said to indicate that the semiconductor processing liquid contains quaternary ammonium hydroxide containing quaternary ammonium ions represented by the above formula (1) and hydroxide ions. By containing quaternary ammonium hydroxide, the semiconductor processing liquid can be used as a semiconductor processing liquid.

[0018] The concentrations of the quaternary ammonium ions represented by the above formula (1) and hydroxide ions in the semiconductor processing solution are not particularly limited, and are preferably produced at 1.00 to 65.00 mass% as quaternary ammonium hydroxide. For example, it is more preferable to use 1.00 to 5.00 mass% as quaternary ammonium hydroxide, and even more preferable to use 1.50 to 3.50 mass%. It is also preferable to use 15.00 to 35.00 mass%, and more preferably 20.00 to 30.00 mass%. The molar concentration of quaternary ammonium hydroxide is preferably 0.10 to 0.50 mol / L, and more preferably 0.15 to 0.35 mol / L.

[0019] The concentration of the quaternary ammonium ion represented by formula (1) in the semiconductor processing solution is preferably 0.01 to 20.00 mass%, more preferably 0.01 to 10.00 mass%, and even more preferably 0.05 to 5.00 mass%. The concentration of hydroxide ions in the semiconductor processing solution is preferably 0.001 ppm by mass to 2.00% by mass, more preferably 0.01 ppm by mass to 0.20% by mass, and further preferably 0.1 ppm by mass to 0.20% by mass.

[0020] The semiconductor processing liquid contains an oxidizing agent. By containing an oxidizing agent, it is possible to add an etching function. The type of oxidizing agent is not particularly limited, and examples thereof include hydrogen peroxide, ozone, hypochlorous acid, chlorous acid, chloric acid, perchloric acid, hypobromous acid, bromous acid, bromic acid, perbromic acid, hypoiodous acid, iodous acid, iodic acid, periodic acid, salts thereof, and ions generated by dissociation of these salts, as well as one or more selected from the group consisting of hydrogen peroxide, ozone, fluorine, chlorine, bromine, iodine, permanganate, chromate, dichromate, and cerium salt. For example, the oxidizing agent may contain at least one halogen oxygen acid ion selected from the group consisting of hypochlorite ion, hypobromite ion, and periodate ion. The type of oxidizing agent that is preferred varies depending on the transition metal to be etched. For example, in the case of Si, W, and Mo, hydrogen peroxide, hypochlorous acid and hypochlorite ions, hypobromous acid and hypobromite ions, and periodic acid and periodate ions are preferably used. In the case of Ti-based metals, hydrogen peroxide is preferably used. In the case of Ru-based metals, hypochlorite ions, hypobromite ions, periodate ions, and permanganate ions are preferably used.

[0021] The oxidizing agent contained in the semiconductor processing liquid may be one or more. By containing multiple types, the etching rate may be stabilized or the stability when the semiconductor processing liquid is reused may be improved. For example, when hypobromite ions are contained as the first oxidizing agent, hypobromite ions consumed in etching metal lose their oxidizing power and change to bromide ions. In this case, the more the amount of bromide ions changed to bromide ions, the lower the etching ability. In semiconductor wafer manufacturing plants, it is common to circulate and reuse the processing liquid from the viewpoint of cost reduction, but if the etching ability decreases due to the reuse of the processing liquid, it becomes difficult to stably manufacture semiconductor wafers. On the other hand, when multiple types of oxidizing agents are contained in the semiconductor processing liquid, for example, when hypochlorite ions are contained in addition to hypobromite ions, bromide ions that have lost their oxidizing power are oxidized by hypochlorite ions and change to hypobromite ions. For this reason, it is possible to suppress the decrease in the concentration of hypobromite ions in the semiconductor processing liquid, and even when the semiconductor processing liquid is reused, the decrease in the etching rate is unlikely to occur.

[0022] (Counter cation of oxidizing agent) The counter cation of the oxidizing agent contained in the semiconductor processing solution of the present invention is not particularly limited, but is preferably a metal ion or an onium ion. As the metal ion, an alkali metal ion such as sodium, potassium, or calcium, or an alkaline earth metal ion such as magnesium or calcium can be used. As the onium ion, for example, a quaternary ammonium ion represented by the above formula (1) can be used. In semiconductor manufacturing, if metal or metal ions remain on a semiconductor wafer, there is a possibility that abnormalities will occur in the electrical characteristics and processed shape. Therefore, it is desirable to contain as few metals and metal ions as possible, and therefore an onium ion is preferable as the counter cation of the oxidizing agent.

[0023] (hydrogen peroxide) The hydrogen peroxide that can be contained in the semiconductor processing solution of the present invention can be prepared by adding a commercially available aqueous hydrogen peroxide solution to the semiconductor processing solution. The content of hydrogen peroxide in the semiconductor processing solution is not particularly limited, but is preferably from 0.001 mol / L to 6.0 mol / L, and more preferably from 0.01 mol / L to 3.0 mol / L. By setting the hydrogen peroxide content within the above range, it becomes possible to etch transition metals stably at a sufficient rate. If the content is less than 0.001 mol / L, the etching rate of transition metals is low and practical use is low. On the other hand, if the content exceeds 6.0 mol / L, hydrogen peroxide is easily decomposed, making it difficult to stably etch transition metals. The content of hydrogen peroxide in a semiconductor processing solution can be confirmed by a widely known method. For example, sulfuric acid is added to a semiconductor processing solution containing hydrogen peroxide, and the hydrogen peroxide concentration can be determined by oxidation-reduction titration using a potassium permanganate solution under sulfuric acid acidity.

[0024] (Hypochlorite ion) The hypochlorous acid and hypochlorite ions that can be contained in the semiconductor processing solution of the present invention may be generated in the processing solution, or may be added to the processing solution as hypochlorite.The hypochlorite referred to here is a salt containing hypochlorite ions, or a solution containing the salt.To generate hypochlorite ions in the processing solution, for example, chlorine gas may be blown into the processing solution.In this case, from the viewpoint of efficiently generating hypochlorite ions, the processing solution is preferably 50°C or less.If the processing solution is 50°C or less, not only can hypochlorite ions be efficiently generated, but the generated hypochlorite ions can be stably used in the processing solution. Furthermore, in order to dissolve more chlorine in the treatment liquid, the temperature of the treatment liquid is more preferably 30°C or less, and most preferably 25°C or less. The lower limit of the temperature of the treatment liquid is not particularly limited, but it is preferable that the treatment liquid does not freeze. Therefore, the treatment liquid is preferably -35°C or more, more preferably -15°C or more, and most preferably 0°C or more. The pH of the treatment liquid into which the chlorine gas is blown is not particularly limited, but if the pH of the treatment liquid is alkaline, it can be used for semiconductor processing immediately after the generation of hypochlorite ions.

[0025] Furthermore, when hypochlorite ions are generated by blowing chlorine gas into the treatment liquid, chloride ions (Cl - ) improves the solubility of chlorine gas (Cl2). The Cl2 dissolved in the treatment solution is converted to Cl - or Cl3 - Reacts with Cl3 - or Cl5 - This is because they form complex ions such as Cl2 and Cl2, which are stable in the treatment solution. - , Cl3 - , Cl5 - A treatment liquid containing a large amount of these compounds can generate a larger amount of hypochlorite ions, and therefore can be suitably used as the treatment liquid of the present invention. In addition, hypochlorite ions can be produced in the treatment liquid by oxidizing chlorine-containing compounds with an oxidizing agent.

[0026] To add hypochlorite ions as a compound to the treatment liquid, hypochlorous acid, chlorine water, and / or hypochlorite may be added. As hypochlorite, sodium hypochlorite, potassium hypochlorite, and tetraalkylammonium hypochlorite are preferable, and hypochlorous acid or tetraalkylammonium hypochlorite is more preferable because they do not contain metal ions that are problematic in semiconductor manufacturing. The tetraalkylammonium hypochlorite can be easily obtained by passing chlorine gas through a tetraalkylammonium hydroxide solution. It can also be obtained by mixing hypochlorous acid with a tetraalkylammonium hydroxide solution. Furthermore, tetraalkylammonium hypochlorite can also be obtained by replacing the cation contained in hypochlorite such as sodium hypochlorite with tetraalkylammonium ion using ion exchange resin.

[0027] The concentration of the hypochlorite ion in the semiconductor processing solution of the present invention is not particularly limited as long as it does not deviate from the object of the present invention, but is preferably 0.001 mol / L or more and 1.5 mol / L or less. If it is less than 0.001 mol / L, the etching rate of the transition metal is low and practical. On the other hand, if it exceeds 1.5 mol / L, the decomposition of the hypochlorite ion is likely to occur, so that the etching rate of the transition metal is difficult to stabilize. In order to stably etch the transition metal at a sufficient speed, the concentration of the hypochlorite ion is preferably 0.001 mol / L or more and 1.5 mol / L or less in terms of the amount of chlorine contained in the hypochlorite ion, more preferably 0.005 mol / L or more and 1.0 mol / L or less, and most preferably 0.01 mol / L or more and 0.40 mol / L or less.

[0028] The concentration of hypochlorite ions in the semiconductor processing solution can be confirmed by using a widely known method. For example, by using ultraviolet-visible absorptiometry, the absorption caused by hypochlorite ions can be easily confirmed, and the hypochlorite ion concentration can be obtained from the intensity of the absorption peak (approximately around 292 nm, depending on the pH of the processing solution and the hypochlorite ion concentration, etc.). Furthermore, the hypochlorite ion concentration can also be obtained by iodometric titration. In addition, the hypochlorite ion concentration can be obtained from the oxidation-reduction potential (ORP) of the processing solution. From the viewpoint of non-contact and continuous measurement, measurement by ultraviolet-visible absorptiometry is the most preferable. Note that when measuring the hypochlorite ion concentration by ultraviolet-visible absorptiometry, if there is absorption due to other chemical species, the hypochlorite ion concentration can be obtained with sufficient accuracy by performing data processing such as spectrum division and baseline correction, and appropriate selection of a reference.

[0029] (Hypobromite ion) The hypobromite ion that can be contained in the semiconductor processing solution of the present invention may be generated in the semiconductor processing solution, or may be added to the semiconductor processing solution as a hypobromite salt. The hypobromite salt referred to here means a salt containing hypobromite ion, or a solution containing the salt. Hypobromite ion (BrO -In order to generate hypobromite ions (also written as BrO) in the semiconductor processing solution, for example, bromine gas may be blown into the semiconductor processing solution. In this case, from the viewpoint of efficiently generating hypobromite ions, the semiconductor processing solution is preferably at a temperature of 20° C. or higher and 50° C. or lower. If the semiconductor processing solution is at 50° C. or lower, not only can hypobromite ions be efficiently generated, but the generated hypobromite ions can be stably used in semiconductor processing. Furthermore, in order to dissolve as much bromine as possible in the semiconductor processing solution, the temperature of the semiconductor processing solution is more preferably 20° C. or higher, and most preferably 30° C. or higher. There are no particular limitations on the pH of the semiconductor processing solution into which the bromine gas is blown, but if the pH of the semiconductor processing solution is alkaline, it can be used for semiconductor processing immediately after the generation of hypobromite ions.

[0030] Furthermore, when hypobromite ions are generated by blowing bromine gas into the semiconductor processing liquid, bromide ions (Br - ) improves the solubility of bromine gas (Br2). Br2 dissolved in the semiconductor processing solution becomes Br - Or Br3 - It reacts with Br3 - or Br5 - This is because they form complex ions such as Br2 and Br2, which are stable in the semiconductor processing solution. - , Br3 - , Br5 - A semiconductor processing solution containing a large amount of these compounds can generate a larger amount of hypobromite ions, and therefore can be suitably used as the semiconductor processing solution of the present invention.

[0031] In addition, hypobromite ions can be produced in the semiconductor processing solution by oxidizing a bromine-containing compound with an oxidizing agent. For example, by mixing hypochlorite ions as an oxidizing agent and tetramethylammonium bromide as a bromine-containing compound, the hypochlorite ions can oxidize bromide ions to produce hypobromite ions. To add hypobromite ions as a compound to the semiconductor processing solution, hypobromous acid, bromine water, and / or hypobromite may be added. As hypobromite, sodium hypobromite, potassium hypobromite, and tetraalkylammonium hypobromite are preferable, and hypobromite or tetraalkylammonium hypobromite are more preferable because they do not contain metal ions that are problematic in semiconductor manufacturing. The above-mentioned tetraalkylammonium hypobromite can be easily obtained by passing bromine gas through a tetraalkylammonium hydroxide solution. It can also be obtained by mixing hypobromous acid with a tetraalkylammonium hydroxide solution. Furthermore, tetraalkylammonium hypobromite can also be obtained by replacing the cations contained in hypobromites such as sodium hypobromite with tetraalkylammonium ions using an ion exchange resin.

[0032] The content of hypobromite ions in the semiconductor processing solution is not particularly limited, but is preferably from 0.001 mol / L to 0.50 mol / L, and more preferably from 0.001 mol / L to 0.20 mol / L. The content of hypobromite ions in the above range makes it possible to etch transition metals stably at a sufficient rate. If the content is less than 0.001 mol / L, the rate at which transition metals are etched is low and practical. On the other hand, if the content exceeds 0.50 mol / L, the hypobromite ions are likely to decompose, making it difficult to stably etch transition metals. The content of hypobromite ions in the semiconductor processing solution can be confirmed using a widely known method. For example, if ultraviolet-visible absorptiometry is used, absorption due to hypobromite ions can be easily confirmed, and the hypobromite ion concentration can be determined from the intensity of the absorption peak (which depends on the pH of the residue removal solution, the hypobromite ion concentration, etc., but is generally around 330 nm). Furthermore, the hypobromite ion concentration can also be determined by iodometric titration. In addition, the hypobromite ion concentration can be determined from the oxidation-reduction potential (ORP) of the residue removal solution. Measurement by ultraviolet-visible absorptiometry is most preferable from the viewpoint of non-contact and continuous measurement. When measuring the hypobromite ion concentration by ultraviolet-visible spectrophotometry, if there is absorption due to other chemical species, the hypobromite ion concentration can be measured with sufficient accuracy by performing data processing such as spectrum division and baseline correction, and by appropriately selecting a reference.

[0033] (Periodate Compounds) Examples of periodic acid compounds that can be contained in the semiconductor processing solution of the present invention include orthoperiodic acid, metaperiodic acid, and ions thereof. The processing solution of the present invention containing these periodic acids can be prepared by adding commercially available periodic acid to the semiconductor processing solution. The content of the periodate compound in the semiconductor processing solution is not particularly limited, but is preferably from 0.001 mol / L to 1.0 mol / L, and more preferably from 0.01 mol / L to 0.5 mol / L. By setting the content of the periodate compound within the above range, it becomes possible to etch the transition metal at a stable and sufficient rate. If the content is less than 0.001 mol / L, the etching rate of the transition metal is low and the practicality is low. On the other hand, if the content exceeds 1.0 mol / L, the etching of the transition metal becomes difficult to stabilize. The content of the periodate compound in the semiconductor processing solution can be confirmed by a widely known method. For example, sulfuric acid can be added to the semiconductor processing solution containing the periodate compound, and the periodate concentration can be determined by iodometric titration under sulfuric acid acidity.

[0034] The halide ion is not particularly limited, but specific examples include one or more selected from the group consisting of chloride ions, bromide ions, and iodide ions. Chloride ions or bromide ions are also preferred. If the semiconductor processing solution contains halide ions, roughness of the metal surface after etching can be suppressed. It is presumed that halogens are present to a certain degree evenly on the metal surface in the processing solution, so that it is possible to control the etching rate of the metal by the oxidizing agent to a certain degree. It is presumed that the surface roughness caused by etching can be suppressed by uniformizing the etching rate of the metal.

[0035] The concentration of halide ions in the semiconductor processing liquid is not particularly limited, but is preferably 0.01 ppm by mass to 20.0% by mass, more preferably 0.1 ppm by mass to 10.0% by mass, and further preferably 0.1 ppm by mass to 5.0% by mass. If the semiconductor processing liquid contains a large amount of halide ions, the halide ions may remain on the surface of the semiconductor. In such a case, the physical properties of the semiconductor may be deteriorated. In addition, if the concentration of halide ions in the semiconductor processing liquid is less than 0.01 ppm by mass, surface roughness may occur due to non-uniform etching. When the concentration of the halide ions is within the above range, the physical properties of a semiconductor obtained using the semiconductor processing solution tend to be improved.

[0036] The concentration of halide ions in the semiconductor processing solution can be analyzed by ion chromatography, and in particular when the alkaline aqueous solution is highly concentrated, analysis by the neutralization method is effective. Specifically, before the semiconductor processing solution is introduced into anion ion chromatography, the cations in the processing solution are exchanged for hydrogen ions, and the hydroxide ions are converted into water. This makes it possible to remove the hydroxide ions. Furthermore, the sensitivity is increased by concentrating the solution. Using this method, it is possible to measure low concentrations of halide ions. The details will be described later.

[0037] The semiconductor processing liquid contains water. The form of the water is not particularly limited, and any known water can be used, and ultrapure water with reduced metal impurities is particularly preferred. The content of water in the semiconductor processing liquid is not particularly limited, but is preferably 10.00 mass% or more, more preferably 20.00 mass% or more, and even more preferably 30.00 mass% or more. It is also preferably 99.99 mass% or less, and even more preferably 99.90 mass% or less. For example, it is preferably 10.00 to 99.99 mass%, more preferably 20.00 to 99.99 mass%, and even more preferably 30.00 to 99.90 mass%.

[0038] The semiconductor processing solution may further contain one or more compounds selected from the group consisting of alcohols and amines, which improves the wettability of the transition metal surface and makes it easier to suppress surface roughness caused by non-uniform etching. The concentration of one or more compounds selected from the group consisting of alcohols and amines in the semiconductor processing liquid is not particularly limited, but is preferably 0.1 ppb to 1.0% by mass, and more preferably 1 ppb to 0.1% by mass. The alcohol is not particularly limited, and known alcohols can be used. For example, primary alcohols such as methanol, ethanol, and 1-propanol, secondary alcohols such as 2-propanol and 2-butanol, and tertiary alcohols such as 2-methyl-2-propanol can be mentioned. The valence of the alcohol is not particularly limited, and monohydric alcohols and dihydric or higher alcohols can be used. Among them, primary alcohols are preferred from the viewpoint of low cost and easy availability. In addition, alcohols having 16 or less carbon atoms (more preferably 2 to 8, and even more preferably 2 to 4) are preferred from the viewpoint that a long chain increases the possibility of causing adsorption inhibition during semiconductor processing.

[0039] The amine is not particularly limited, and known amines can be used. For example, primary amines such as methylamine, secondary amines such as dimethylamine, and tertiary amines such as trimethylamine can be mentioned. The valence of the amine is not particularly limited, and monovalent amines or divalent or higher amines can be used. Among them, tertiary amines are preferred from the viewpoint of low cost and easy availability. Furthermore, amines having a carbon number of 16 or less (more preferably 2 to 8, and even more preferably 2 to 4) are preferred from the viewpoint that a long chain increases the possibility of causing adsorption inhibition during semiconductor processing.

[0040] As a toxicity evaluation of a quaternary ammonium hydroxide aqueous solution, it is preferable that the median lethal dose (LD50) value calculated based on 100% by mass of the hydroxide of the quaternary ammonium ion exceeds 50 mg / kg in a toxicity test using rats based on OECD TG420 acute oral toxicity. This leads to higher safety during use and easier connection to low environmental load. In addition, in the GHS classification, if the LD50 value is 50 mg / kg or less, it corresponds to category 2, and regulations on storage, transportation, etc. are strict, and if it is 5 mg / kg or less, it becomes category 1, which is even stricter, so it is preferable that it exceeds 50 mg / kg. The LD50 value is more preferably more than 100 mg / kg, even more preferably more than 200 mg / kg, and particularly preferably more than 300 mg / kg. The LD50 value can be preferably more than 50 mg / kg and not more than 1000 mg / kg, more preferably more than 100 mg / kg and not more than 1000 mg / kg, even more preferably more than 200 mg / kg and not more than 1000 mg / kg, and most preferably more than 300 mg / kg and not more than 1000 mg / kg. The LD50 value can be adjusted by changing the type of quaternary ammonium ion represented by the above formula (1).

[0041] In view of this toxicity, for example, R 1 , R 2 , and R 3 is an alkyl group having one carbon atom, and R 4 is a quaternary ammonium ion, R is an alkyl group having 2 to 4 carbon atoms. 1 , R 2 , R 3 , and R 4 R is a quaternary ammonium ion, where R is an alkyl group having two carbon atoms. 1 , R 2 , R 3 , and R 4 R is a quaternary ammonium ion, where R is an alkyl group having 3 carbon atoms. 1 , R 2 , R 3 , and R 4is an alkyl group having 4 carbon atoms. More specifically, an ethyltrimethylammonium ion, a propyltrimethylammonium ion, a butyltrimethylammonium ion, a tetraethylammonium ion, a tetrapropylammonium ion, or a tetrabutylammonium ion is preferred.

[0042] The semiconductor processing solution can be used as, for example, an etching solution. It can also be used as, for example, a transition metal semiconductor processing solution. The transition metal in the present invention includes, for example, one or more metals selected from the group consisting of Si, Ru, Rh, Ti, Ta, Co, Cr, Hf, Os, Pt, Ni, Mn, Cu, Zr, La, Mo, and W. It may also include oxides, nitrides, oxynitrides, carbides, and silicides of these transition metals. Furthermore, the semiconductor processing liquid can be used as a low-toxicity semiconductor processing liquid. That is, one embodiment of the present invention is a method of using the semiconductor processing liquid of the present invention as a low-toxicity semiconductor processing liquid.

[0043] The method for producing a semiconductor processing solution of the present invention is not particularly limited, and may include, for example, a preparation step A of preparing an alkaline aqueous solution for semiconductors as a raw material, a mixing step of mixing the alkaline aqueous solution for semiconductors, an oxidizing agent, and, if necessary, water to a predetermined concentration to obtain a mixture, and a dissolving step of dissolving the obtained mixture to a uniform concentration. These steps may also be combined into one step.

[0044] The preparation step A for preparing an alkaline aqueous solution for semiconductors is not particularly limited, but from the viewpoint of suppressing the halide ion concentration, it is preferable to obtain an alkaline aqueous solution for semiconductors by electrolyzing an aqueous solution of a quaternary ammonium halide. That is, the preparation step A preferably includes an electrolysis step of electrolyzing an aqueous solution of a quaternary ammonium halide. Specifically, it is preferable to include an electrolysis step of electrolyzing an aqueous solution of a quaternary ammonium halide containing the following (A), (B), and (E). As (A), (B), and (E), those described above can be used. (A) A quaternary ammonium ion represented by the following formula (1): (B) Halide ions (E)Water [ka] (In the formula, R 1 , R 2 , R 3 , and R 4 are each independently an alkyl group having 1 to 16 carbon atoms (preferably 1 to 8, more preferably 1 to 4), provided that R 1 , R 2 , R 3 , and R 4 Among these, one or more alkyl groups have 2 to 16 carbon atoms (preferably 2 to 8, more preferably 2 to 4).

[0045] To produce an alkaline aqueous solution for semiconductors by electrolysis, an electrolytic cell can be used, which has one or more cation exchange membranes arranged between an anode and a cathode, a raw material chamber for supplying a quaternary ammonium halide aqueous solution as a raw material, and a base chamber (cathode chamber) in which a quaternary ammonium hydroxide aqueous solution is produced. In a production method using this electrolytic cell, quaternary ammonium ions contained in the quaternary ammonium halide aqueous solution pass through the cation exchange membrane arranged on the cathode side during electrolysis. As a result, a quaternary ammonium hydroxide aqueous solution is produced in the base chamber. The above example is an example in which one or more cation exchange membranes are arranged, but an electrolytic cell in which a plurality of membranes selected from the group consisting of cation exchange membranes, anion exchange membranes, and bipolar membranes (composite membranes consisting of a cation exchange membrane and an anion exchange membrane) are arranged may also be used as long as an aqueous quaternary ammonium hydroxide solution can be produced.

[0046] At this time, the halide ions, which are the anions of the quaternary ammonium halide, move to the anode side, but some of the halide ions also move to the cathode side by diffusion. Therefore, depending on the concentration of the liquid used as the raw material, about 1 to several tens of ppm of halide ions may be mixed into the aqueous solution of quaternary ammonium hydroxide.

[0047] The method for producing a semiconductor processing solution may include, prior to the above-mentioned electrolysis step, a preparation step B of preparing an aqueous solution of a quaternary ammonium halide to be used as a raw material in the electrolysis step. The preparation step B is not particularly limited, and for example, a quaternary ammonium halide aqueous solution can be prepared by producing a quaternary ammonium halide aqueous solution. The method for producing the quaternary ammonium halide aqueous solution is not particularly limited. For example, from the viewpoint of productivity and quality, it is preferable to use a step of reacting trialkylamine with alkyl halide in ultrapure water to obtain a quaternary ammonium halide.

[0048] The trialkylamine and alkyl halide used as raw materials are not particularly limited as long as they can produce the quaternary ammonium ion represented by the above formula (1). Specifically, the alkyl groups contained in the trialkylamine and the alkyl halide can be such that one or more alkyl groups have 2 to 16 (preferably 2 to 8, more preferably 2 to 4) carbon atoms and the other alkyl groups have 1 to 16 (preferably 1 to 8, more preferably 1 to 4) carbon atoms. The halide ion, which is the anion of the alkyl halide, may be the same as that described above in (B). Since impurities contained in the quaternary ammonium halide diffuse into the aqueous solution of quaternary ammonium hydroxide, it is preferable to use a high-purity quaternary ammonium halide. Specifically, it is preferable that the concentration of any one metal selected from lithium, sodium, potassium, aluminum, magnesium, calcium, chromium, manganese, iron, nickel, cobalt, copper, silver, cadmium, barium, zinc, and lead in the aqueous solution of quaternary ammonium halide is 0.01 ppt to 1 ppb by mass. EXAMPLES

[0049] Examples are given below to specifically explain the present invention, but the present invention is not limited to these. The evaluations performed in the examples and comparative examples were performed by the following methods.

[0050] [Evaluation method] 1) Halide ion concentration The halide ion concentration in the semiconductor processing solution was measured using an ion chromatography analyzer (DIONEX INTEGRION HPLC, Thermo Scientific). A KOH aqueous solution was used as the eluent, and the solution was passed through at a flow rate of 1.2 mL / min. The column used was an anion analysis column for hydroxide-based eluents (AS15, Thermo Scientific), and the column temperature was set to 30°C. After removing background noise with a suppressor, the halide ions in the processing solution were quantified with an electrical conductivity detector.

[0051] 2) Hydroxide ion concentration 1 mL of the aqueous solutions prepared in the examples and comparative examples was subjected to neutralization titration with 0.1 mol / L hydrochloric acid using a Hiranuma automatic titrator (COM-1700, manufactured by Hiranuma). The hydroxide ion concentration was calculated from the amount of 0.1 mol / L hydrochloric acid required for neutralization.

[0052] 3) Etching test 60 mL of the treatment solution of the embodiment was prepared in a fluororesin container with a lid (AsOne, PFA container 94.0 mL). Each evaluation semiconductor wafer piece having a size of 10×20 mm was immersed in the treatment solution at 25° C. or 50° C. for 1 minute, and the etching rate was calculated by dividing the change in film thickness before and after treatment by the immersion time, and evaluated according to the following criteria. In each case, ratings A to C are acceptable levels, and rating D is unacceptable. (Titanium nitride film, ruthenium film, molybdenum film) A:>50Å / min B:50~20Å / min C: 20-10Å / min (tolerance level) D: No etching possible (tungsten film) A:>500Å / min B:500~100Å / min C: 100-10Å / min (tolerance level) D: No etching possible

[0053] 4) Surface evaluation after etching The metal surface was observed before and after etching using a field emission scanning electron microscope (JSM-7800F Prime, manufactured by JEOL Ltd.) to check for the presence or absence of surface roughness, and was rated according to the following criteria. Surface roughness was rated from A to D in descending order, with A to C being acceptable levels and D being unacceptable. A: No surface roughness is observed. B: Some surface roughness is observed. C: Roughness is observed over the entire surface, but the roughness is shallow. D: Roughness is observed over the entire surface, and the roughness is deep.

[0054] 5) Toxicity testing Data on the median lethal dose (LD50) was collected in toxicity tests using rats. For substances for which data was not disclosed, toxicity tests based on OECD TG420 acute oral toxicity were conducted to obtain data. The median lethal dose obtained was converted to 100% by mass of the quaternary ammonium hydroxide aqueous solution, and evaluation was performed based on the following criteria. When two or more types of quaternary ammonium hydroxide aqueous solutions were mixed, the median lethal dose of each quaternary ammonium hydroxide aqueous solution was multiplied by the mixing ratio and the sum was calculated. The results are shown in Table 1. A: The lethal dose is more than 2000mg / kg. B: Median lethal dose is between 300mg / kg and 2000mg / kg C: Median lethal dose: 50mg / kg to 300mg / kg D: The lethal dose is 50mg / kg or less. A semiconductor processing liquid having a low toxicity can be said to be rated A to C, and a liquid having a rating of A to B is preferable.

[0055] (reagent) The reagents used in the examples and comparative examples are as follows. Hydrogen peroxide (H2O2): Fujifilm Wako Pure Chemical Industries, Ltd. Orthoperiodic acid (H5IO6): Fujifilm Wako Pure Chemical Industries, Ltd. Metaperiodic acid (HIO4): Sigma-Aldrich Hydrochloric acid (HCl): Kanto Chemical Co., Ltd. Hydrobromic acid (HBr): Tama Chemicals Hydroiodic acid (HI): Tokyo Chemical Industry Chemical Co., Ltd. Ethyltrimethylammonium hydroxide (ETMAH, made from raw materials) Propyltrimethylammonium hydroxide (PTMAH, made from raw materials) Butyltrimethylammonium hydroxide (BTMAH, made from raw materials) Tetrapropylammonium hydroxide (TPAH, manufactured by Tokyo Chemical Industry Co., Ltd.) Tetrabutylammonium hydroxide (TBAH, manufactured by Tokyo Chemical Industry Co., Ltd.) Tetramethylammonium hydroxide (TMAH, manufactured by Tokuyama) Here, TPAH, TBAH and TMAH were prepared to the concentrations shown in Table 1.

[0056] (Preparation of Quaternary Ammonium Hydroxide Aqueous Solution) ETMAH (ethyltrimethylammonium hydroxide), PTMAH (propyltrimethylammonium hydroxide), and BTMAH (butyltrimethylammonium hydroxide) were prepared by the following procedure. A quaternary ammonium halide aqueous solution was prepared from the raw materials trialkylamine and alkyl halide, and this was used to prepare a quaternary ammonium hydroxide aqueous solution by electrolysis. Specifically, in the case of ETMAH, trimethylamine and ethyl chloride were charged in a molar ratio of 1:1 into a reaction vessel containing ultrapure water, and the reaction temperature was maintained at 60°C to prepare a 50% by mass ethyltrimethylammonium chloride aqueous solution. The unreacted trimethylamine and ethyl chloride, and the by-product ethanol were each removed under reduced pressure until they were less than 100 ppm, and then ETMAH was prepared using the electrolytic cell shown in Figure 1. In FIG. 1, 1 indicates an anode, 2 indicates a cathode, 3 indicates a power source, 4 indicates an anode chamber, 5 indicates a raw material chamber, 6 indicates an intermediate chamber, 7 indicates a cathode chamber, 8 indicates an anion exchange membrane, and 9 indicates a cation exchange membrane.

[0057] A platinum-plated nickel plate was used as the cathode, a platinum-plated titanium plate as the anode, two Nafion N324 (Chemours) cation exchange membranes, and ASE (Astrom) anion exchange membrane. 0.5N hydrochloric acid was circulated in the anode chamber, a 50% by mass aqueous solution of ethyltrimethylammonium chloride was circulated in the raw material chamber between the anion exchange membrane and the cathode side cation exchange membrane, and ultrapure water was circulated in the intermediate chamber between the cathode chamber and the two cation exchange membranes. The current density was gradually increased until a final current density of 30 A / dm was achieved. 2 Electrolysis was carried out continuously while maintaining the temperature at 40° C. During electrolysis, an aqueous ethyltrimethylammonium chloride solution was replenished so that the ethyltrimethylammonium chloride concentration in the raw material chamber was maintained at 40 mass% or more, and when the ETMAH concentration in the cathode chamber increased to 30 mass%, electrolysis was terminated and an aqueous ETMAH solution was obtained.

[0058] The preparation of PTMAH and BTMAH was carried out in the same manner as the preparation of ETMAH, except that propyl chloride and butyl chloride, respectively, were used as the alkyl halide.

[0059] <Examples 1 to 5, Comparative Examples 1 and 5> (Preparation of semiconductor processing solution containing hydrogen peroxide) Ion-exchanged water, hydrogen peroxide, and hydrochloric acid were added to the quaternary ammonium hydroxide aqueous solution obtained by the above operation to prepare a treatment liquid having the composition shown in Table 1. However, in Example 4, the TBAH aqueous solution prepared in the reagent column was used instead of the quaternary ammonium hydroxide aqueous solution obtained by the above operation. Also in Example 5, the TPAH aqueous solution prepared in the reagent column was used instead of the quaternary ammonium hydroxide aqueous solution obtained by the above operation. Furthermore, in Comparative Examples 1 and 5, the TMAH aqueous solution prepared in the reagent column was used instead of the quaternary ammonium hydroxide aqueous solution obtained by the above operation. The amine concentration in each of the semiconductor processing solutions was less than 100 ppm by mass, and the alcohol concentration in each of the semiconductor processing solutions was less than 100 ppm by mass.

[0060] <Examples 6 to 10, Comparative Example 2> (Preparation of Semiconductor Processing Solution Containing Hypochlorite Ions) The aqueous quaternary ammonium hydroxide solution obtained by the above procedure was mixed with ion-exchanged water in a 2 L three-necked glass flask (manufactured by Cosmos Bead Co., Ltd.) to obtain an aqueous quaternary ammonium hydroxide solution of 1.69 mol / L, with a pH of 14.2. Next, a rotor (AsOne, total length 30 mm x diameter 8 mm) was placed in the three-neck flask, and a thermometer protection tube (Cosmos Bead, bottom-sealed type) and a thermometer were placed in one opening. Furthermore, a PFA tube (Flon Industries, F-8011-02) connected to a chlorine gas cylinder and a nitrogen gas cylinder and capable of switching between chlorine gas and nitrogen gas at will was connected to the other opening, and the tip of the PFA tube was immersed in the bottom of the aqueous solution. In addition, the remaining opening was connected to a gas washing bottle (AsOne, gas washing bottle, model number 2450 / 500) filled with a 5% by weight aqueous solution of sodium hydroxide. Carbon dioxide in the gas phase was expelled by flowing nitrogen gas at 200 ccm (25°C) from the PFA tube for 20 minutes.

[0061] Then, a magnetic stirrer (AsOne, C-MAG HS10) was placed at the bottom of the three-neck flask and rotated at 300 rpm, while cooling the outer periphery of the three-neck flask with ice water and feeding chlorine gas (Fujiox, specification purity 99.4%) at 200 ccm (25 ° C) for 360 minutes to obtain a 1.5 mol / L aqueous solution of quaternary ammonium hypochlorite (containing 1.5 mol / L quaternary ammonium chloride and 0.05 mol / L quaternary ammonium hydroxide). At this time, the liquid temperature during the reaction was 11 ° C. Hydrochloric acid and an aqueous quaternary ammonium solution were added to the obtained aqueous quaternary ammonium hypochlorite solution to prepare a treatment liquid having the composition shown in Table 1. However, in Comparative Example 2, the aqueous solution of TMAH prepared in the Reagent section was used in place of the aqueous solution of quaternary ammonium hydroxide obtained by the above procedure. The amine concentration in each of the semiconductor processing solutions was less than 100 ppm by mass, and the alcohol concentration in each of the semiconductor processing solutions was less than 100 ppm by mass.

[0062] <Examples 11 to 15, Comparative Example 3> (Preparation of Semiconductor Processing Solution Containing Hypobromite Ions) A 0.5 mol / L quaternary ammonium hypobromite solution was obtained by adding hydrobromic acid and a quaternary ammonium hydroxide solution to the mixture containing the 1.5 mol / L quaternary ammonium hypochlorite solution and the quaternary ammonium hydroxide obtained by the above operation. A treatment solution having the composition shown in Table 1 was prepared by adding ion-exchanged water, hydrobromic acid, and a quaternary ammonium hydroxide solution to the obtained quaternary ammonium hypobromite solution. However, in Comparative Example 3, the aqueous solution of TMAH prepared in the Reagent section was used in place of the aqueous solution of quaternary ammonium hydroxide obtained by the above procedure. The amine concentration in each of the semiconductor processing solutions was less than 100 ppm by mass, and the alcohol concentration in each of the semiconductor processing solutions was less than 100 ppm by mass.

[0063] <Examples 16 to 20, Comparative Example 4> (Preparation of semiconductor processing solution containing periodate compound) Orthoperiodic acid or metaperiodic acid was added to the aqueous quaternary ammonium hydroxide solution obtained by the above procedure, and then ion-exchanged water and hydroiodic acid were added to prepare a treatment liquid having the composition shown in Table 1. However, in Comparative Example 4, the aqueous solution of TMAH prepared in the Reagent section was used in place of the aqueous solution of quaternary ammonium hydroxide obtained by the above procedure. The amine concentration in each of the semiconductor processing solutions was less than 100 ppm by mass, and the alcohol concentration in each of the semiconductor processing solutions was less than 100 ppm by mass. [Table 1] In the table, ETMA+ represents ethyltrimethylammonium ion, PTMA+ represents propyltrimethylammonium ion, BTMA+ represents butyltrimethylammonium, TBA+ represents tetrabutylammonium ion, TPA+ represents tetrapropylammonium ion, TMA+ represents tetramethylammonium ion, and ClO represents hypochlorite ion (ClO- ), and BrO stands for hypobromite ion (BrO - ) [Table 2]

[0064] In Examples 1 to 20, the etching rate, surface roughness, and toxicity test results were all rated C or higher, whereas in Comparative Examples 1 to 5, the toxicity test result was all rated D. Furthermore, in Comparative Example 5, the surface roughness was also rated D. From these results, it was demonstrated that the semiconductor processing liquid according to the embodiment of the present invention can suppress surface roughness after etching, and is a low-toxicity semiconductor processing liquid. [Explanation of symbols]

[0065] 1: Anode 2: Cathode 3: Power supply 4:Anode chamber 5: Raw material room 6: Intermediate chamber 7: Cathode chamber 8: Anion exchange membrane 9: Cation exchange membrane

Claims

1. A semiconductor processing solution comprising the following (A) to (E): (A) A quaternary ammonium ion represented by the following formula (1): (B) Halide ion (C) Hydroxide ion (D) Oxidizing agent (E) Water (In the formula, R １ , R ２ , R ３ , and R ４ are each independently an alkyl group having 1 to 16 carbon atoms, provided that R １ , R ２ , R ３ , and R ４ Among these, at least one alkyl group has 2 to 16 carbon atoms, and R 1 , R 2 , R 3 , and R 4 are not all the same alkyl group.

2. A semiconductor processing solution comprising the following (A) to (E): (A) A quaternary ammonium ion represented by the following formula (1): (B) Halide ion (C) Hydroxide ion (D) Oxidizing agent (E) Water (In the formula, R 1 , R 2 , R 3 , and R 4 are each independently an alkyl group having 1 to 16 carbon atoms, provided that at least one of R 1 , R 2 , R 3 , and R 4 has 2 to 16 carbon atoms.) A semiconductor processing solution having an LD50 value calculated based on 100 mass % of the hydroxide of the quaternary ammonium ion, exceeding 50 mg / kg in a toxicity test using rats based on the OECD TG420 acute oral toxicity test.

3. R in the formula (1) １ , R ２ , R ３ , and R ４ The semiconductor processing solution according to claim 2 , wherein not all of the alkyl groups are the same.

4. R in the above formula (1) １ , R ２ , and R ３ is a methyl group, and R ４ The semiconductor processing solution according to claim 1 or 2, wherein is an alkyl group having 2 to 16 carbon atoms.

5. 3. The semiconductor processing solution according to claim 1, wherein the halide ion (B) is a chloride ion or a bromide ion.

6. 3. The semiconductor processing solution according to claim 1, wherein the concentration of said halide ions in said semiconductor processing solution is 0.1 ppm by mass to 5.0% by mass.

7. 3. The semiconductor processing solution according to claim 1, wherein the oxidizing agent contains at least one halogen oxygen acid ion selected from the group consisting of hypochlorite ions, hypobromite ions, and periodate ions.

8. 3. The semiconductor processing solution according to claim 1, further comprising one or more compounds selected from the group consisting of alcohols and amines.

9. A method for using a semiconductor processing solution containing the following (A) to (E) as a low-toxicity semiconductor processing solution: (A) A quaternary ammonium ion represented by the following formula (1): (B) Halide ion (C) Hydroxide ion (D) Oxidizing agent (E) Water (In the formula, R 1 , R 2 , R 3 , and R 4 are each independently an alkyl group having 1 to 16 carbon atoms, provided that at least one of R 1 , R 2 , R 3 , and R 4 has 2 to 16 carbon atoms.)

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