Semiconductor processing liquid, processing method, and method for manufacturing semiconductor substrate

Abstract

A semiconductor processing liquid comprising a carboxylic acid and a hypohalite ion, wherein the concentration of the carboxylic acid is 0.0001-1.0 mol / L, the hypohalite ion is at least one selected from the group consisting of hypochlorite and hypobromite ions, the concentration of the hypohalite ion is 0.0001-3.0 mol / L, and the pH of the semiconductor processing liquid at 25°C is 7.0-14.0.

Description

Semiconductor processing solution, processing method, and method for manufacturing a semiconductor substrate

[0001] This invention relates to a semiconductor processing solution, a processing method, and a method for manufacturing a semiconductor substrate.

[0002] Semiconductor devices have wiring layers formed within them to extract electrical signals generated by transistors to the outside. As semiconductor devices become smaller year by year, using materials with low electromigration resistance or high resistance can lead to a decrease in the reliability of the semiconductor device and hinder high-speed operation. Therefore, wiring materials with high electromigration resistance and low resistance are desired.

[0003] Materials with high electromigration resistance and low resistance have historically included, for example, aluminum and copper. Metal wiring is formed on patterns exposed on an insulating film, but as the wiring width decreases, the embedding ability of the metal deteriorates, leading to problems such as short circuits caused by void formation. Therefore, to improve the embedding ability of the metal, a method is used in which a thin metal film called a liner layer is deposited on a dielectric, and the wiring metal is deposited on top of it. High-melting-point metals such as cobalt and ruthenium are being considered for use in the liner layer for copper wiring.

[0004] When forming a wiring layer on a semiconductor device, the process involves processing the wiring material, and this process can be done using either dry or wet etching. When wet etching the metal of the liner layer, if the wiring metal is also etched at the same time, it can lead to increased resistance due to surface roughness and the risk of short circuits. Therefore, there is a need for a processing solution that selectively etches only the metal of the liner layer.

[0005] Furthermore, it is known that if a metal nobler than the wiring metal is used in the liner layer, galvanic corrosion can occur due to the corrosion potential difference between the two metals, leading to a risk of short circuits due to the dissolution of the wiring metal.

[0006] As a processing solution capable of etching specific metals, Patent Document 1 discloses a composition suitable for etching metallic ruthenium and ruthenium alloys containing ruthenium as a main component, as well as a method for preparing the same.

[0007] Furthermore, Patent Document 2 discloses a corrosion inhibitor / discoloration inhibitor for copper-based materials, characterized by comprising a silane coupling agent that contains one or more elements selected from N, O, and S, and further having a functional group capable of adsorbing carboxyl groups at its molecular ends, or a hydrophobic group.

[0008] Furthermore, Patent Document 3 discloses a polishing method comprising the steps of: forming a film made of a material mainly composed of metal on a substrate having recesses on its surface so as to fill the recesses; and polishing the film to form a conductive film in the recesses by a chemical mechanical polishing method using an abrasive containing a chemical reagent that forms a protective film on the surface of the film by reacting with the material mainly composed of metal, and an etching agent made of the material mainly composed of metal, wherein the etching agent contains aminoacetic acid and / or amide sulfuric acid, an oxidizing agent, and water.

[0009] International Publication No. 2011 / 074601, Japanese Patent Publication No. 59-74283, International Publication No. 2009 / 128494

[0010] However, our investigations have revealed that while the etching solution described in Patent Document 1 can etch high-melting-point metals such as ruthenium, it can also slightly dissolve copper, sometimes leading to the formation of copper oxide precipitates on the copper surface.

[0011] Furthermore, it was found that the treatment solution described in Patent Document 2 can suppress copper corrosion, but it cannot etch ruthenium.

[0012] Furthermore, it was found that the processing solution described in Patent Document 3 could not etch ruthenium, and moreover, the copper corrosion inhibitor inhibited the etching of ruthenium.

[0013] The present invention provides a semiconductor processing solution that can selectively remove a high-melting-point metal from a semiconductor substrate containing a high-melting-point metal and copper without causing galvanic corrosion of the copper. The invention also provides a method for processing a semiconductor substrate using the above-mentioned semiconductor processing solution, and a method for manufacturing a semiconductor substrate.

[0014] The present inventors, in order to solve the problem of selectively removing high-melting-point metals such as ruthenium from copper and preventing galvanic corrosion of copper, have diligently conducted research and found that by using a semiconductor treatment solution containing a carboxylic acid and hypohalite ions, wherein the concentration of the carboxylic acid is 0.0001 mol / L or more and 1.0 mol / L or less, the hypohalite ions are at least one selected from the group consisting of hypochlorite ions and hypobromite ions, the concentration of the hypohalite ions is 0.0001 mol / L or more and 3.0 mol / L or less, and the pH at 25°C is 7.0 or more and 14.0 or less, it is possible to selectively remove high-melting-point metals and prevent copper corrosion and galvanic corrosion of copper due to potential difference.

[0015] In other words, the gist of the present invention is specifically as follows: <1> A semiconductor processing solution comprising a carboxylic acid and a hypohalite ion, wherein the concentration of the carboxylic acid is 0.0001 mol / L or more and 1.0 mol / L or less, the hypohalite ion is at least one selected from the group consisting of hypochlorite ion and hypobromite ion, the concentration of the hypohalite ion is 0.0001 mol / L or more and 3.0 mol / L or less, and the pH at 25°C is 7.0 or more and 14.0 or less. <2> The semiconductor processing solution according to <1>, wherein the carboxylic acid is a compound represented by formula (1). R-COOH ... (1) (In formula (1), R is a hydrogen atom, a C1 to C10 alkyl group having one or more substituents X, or a phenyl group having one or more substituents X, wherein the substituent X is at least one selected from the group consisting of a hydroxyl group, a carbonyl group, and an alkoxy group, and if R has multiple substituents X, each substituent X may be the same or may be different.) <3> The semiconductor processing solution according to <2>, wherein at least one of the substituents X is a carboxyl group. <4> The semiconductor processing solution according to any one of <1> to <3>, wherein the carboxylic acid is a carboxylic acid having one or more alkoxy groups. <5> The semiconductor processing solution according to any one of <1> to <4>, further comprising one or more metals selected from the group consisting of alkali metals and alkaline earth metals, and hydroxide ions. <6> The semiconductor processing solution according to <5>, wherein the total concentration of one or more metals selected from the group consisting of alkali metals and alkaline earth metals is 1 ppm by mass or more and 10.0% by mass or less. <7> A method for processing a semiconductor substrate having copper and a high-melting-point metal, wherein the high-melting-point metal is removed using a semiconductor processing solution described in any of <1> to <6>. <8> The processing method according to <7>, wherein the high-melting-point metal is one or more metals selected from the group consisting of titanium, tantalum, ruthenium, molybdenum, tungsten, chromium, iridium, rhodium, platinum, and niobium. <9> A method for manufacturing a semiconductor substrate, comprising the method according to <7> or <8>.

[0016] According to the present invention, it is possible to provide a semiconductor processing solution that has a sufficient etching rate for high-melting-point metals, particularly ruthenium, without corroding copper, and that prevents copper corrosion by galvanic corrosion even when the high-melting-point metal and copper are in electrical contact. Furthermore, it is possible to provide a processing method using the above semiconductor processing solution and a method for manufacturing a semiconductor substrate.

[0017] This is a schematic diagram of the wiring formation process for semiconductor substrates. This is a schematic diagram of the apparatus used to prepare the tetramethylammonium hypochlorite aqueous solution used in the examples. This is a schematic diagram of the apparatus used to prepare the sodium hypobromite aqueous solution used in the examples.

[0018] Embodiments of the present invention will be described in detail below, but the present invention is not limited to these contents unless it exceeds the spirit of the invention. Furthermore, the present invention can be modified and implemented as desired without departing from its spirit. In addition, when numerical ranges are described in steps, the upper and lower limits of each numerical range can be combined as desired. Also, the expression "A or B" in this specification may be read as "at least one selected from the group consisting of A and B". Also, the expression "amount of B relative to amount of A" in this specification means "amount of B / amount of A". Furthermore, although multiple embodiments are described in this specification, various conditions in each embodiment can be applied to each other to the extent that they are applicable.

[0019] (Semiconductor Processing Solution) The semiconductor processing solution according to one embodiment of the present invention (hereinafter also simply referred to as the processing solution) contains a carboxylic acid and a hypohalite ion, wherein the concentration of the carboxylic acid is 0.0001 mol / L or more and 1.0 mol / L or less, the hypohalite ion is at least one selected from the group consisting of hypochlorite ions and hypobromite ions, the concentration of the hypohalite ion is 0.001 mol / L or more and 3.0 mol / L or less, and the pH at 25°C is 7.0 or more and 14.0 or less. Preferably, the above semiconductor processing solution is an etching solution.

[0020] (Carboxylic Acid) The treatment solution of this embodiment contains a carboxylic acid. The carboxylic acid may exist in the treatment solution of this embodiment in the form of a carboxylic acid, a carboxylic acid ion, or a carboxylic acid salt, but in this specification, carboxylic acids, carboxylic acid ions, and carboxylic acid salts are collectively referred to as "carboxylic acid." Specific examples of carboxylic acids include, for example, at least one selected from the group consisting of glycolic acid, lactic acid, malic acid, tartaric acid, citric acid, mandelic acid, glyceric acid, gluconic acid, 6-hydroxycaproic acid, oxalacetic acid, pyruvic acid, oxoglutaric acid, acetic acid, oxalic acid, malonic acid, succinic acid, diglycolic acid, 1,2,3,4-butanetetracarboxylic acid, formic acid, propionic acid, salicylic acid, methoxyacetic acid, ethoxyacetic acid, methoxybutanoic acid, ethoxybutanoic acid, and 2-methoxybenzoic acid. The inclusion of a carboxylic acid in the treatment solution can suppress the corrosion of copper when a semiconductor substrate containing a high melting point metal and copper is treated with the treatment solution. The reason for this is not entirely clear, but it is presumed that the carboxylic acid forms a complex with copper, creating a protective film on the copper surface and thus suppressing copper corrosion. Therefore, it is preferable that the carboxylic acid is one that can form a complex with copper.

[0021] (Compound represented by formula (1)) The carboxylic acid is preferably a compound represented by the following formula (1): R-COOH ... (1) (In formula (1), R is a hydrogen atom, a C1-C10 alkyl group having one or more substituents X, or a phenyl group having one or more substituents X, and substituent X is at least one selected from the group consisting of a hydroxyl group, a carbonyl group, and an alkoxy group.)

[0022] R is preferably an alkyl group having 1 to 6 carbon atoms, and more preferably an alkyl group having 1 to 4 carbon atoms. Note that the carbon atoms of substituents are not included in the carbon number of R. When R is an alkyl group, it may be a linear alkyl group or a branched alkyl group. The number of substituents X may be one or two or more. The number of substituents X is preferably 1 to 5, and more preferably 1 to 3. When R has multiple substituents X, each substituent X may be the same or different. R may have further substituents in addition to substituent X. When R is an alkyl group having 1 to 10 carbon atoms with one or more substituents X, it is preferable that the carbon atom adjacent to -COOH in formula (1) has substituent X (i.e., it is preferable that at least one substituent X is located at the α position). It is presumed that the carboxylic acid being a compound represented by formula (1) makes it easy to form a strong copper complex, and as a result, it has a high inhibitory effect on copper corrosion.

[0023] The compound represented by formula (1) is preferably at least one selected from the group consisting of glycolic acid, lactic acid, malic acid, tartaric acid, citric acid, mandelic acid, glyceric acid, gluconic acid, 6-hydroxycaproic acid, pyruvic acid, oxoglutaric acid, oxalacetic acid, and 2-methoxybenzoic acid. More preferably, the compound represented by formula (1) is at least one selected from the group consisting of glycolic acid, lactic acid, malic acid, glyceric acid, tartaric acid, and citric acid.

[0024] Furthermore, it is presumed that compounds having a carboxyl group and a hydroxyl group, or a carboxyl group and a ketone group, are more likely to form a stronger copper complex than compounds with only a carboxyl group as a substituent, resulting in a higher inhibitory effect on copper corrosion. Therefore, it is more preferable that at least one of substituent X is a hydroxyl group or a ketone group. That is, it is more preferable that the compound represented by formula (1) has one or more carboxyl groups and one or more hydroxyl groups or ketone groups. Furthermore, it is presumed that compounds having multiple carboxyl groups are more likely to form a stronger copper complex, resulting in a higher inhibitory effect on copper corrosion. Therefore, it is more preferable that at least one of substituent X is a carboxyl group. That is, it is more preferable that the compound represented by formula (1) has two or more carboxyl groups. It is even more preferable that there are multiple substituent X, at least one of which is a carboxyl group, and at least one of which is a hydroxyl group or a ketone group. That is, it is even more preferable that the compound represented by formula (1) has two or more carboxyl groups and one or more hydroxyl groups or ketone groups.

[0025] The concentration of carboxylic acid in the treatment solution is 0.0001 mol / L or more and 1.0 mol / L or less. A concentration of 1.0 mol / L or less suppresses the decomposition of hypohalite ions, thereby improving the stability of hypohalite ions. Furthermore, a concentration of 0.0001 mol / L or more provides sufficient copper corrosion inhibition. In this embodiment, the carboxylic acid contained in the treatment solution is preferably 0.001 mol / L or more and 1.0 mol / L or less, and more preferably 0.005 mol / L or more and 0.1 mol / L or less, relative to the total volume of the treatment solution, from the viewpoint of treatment solution stability and copper corrosion inhibition. Also, two or more types of carboxylic acids may be contained in the treatment solution. In this case, the total concentration of carboxylic acids is preferably 0.0001 mol / L or more and 1.0 mol / L or less, preferably 0.001 mol / L or more and 0.005 mol / L or more and 0.1 mol / L or less.

[0026] (Hypohalite Ion) The treatment solution in this embodiment contains hypohalite ions. The hypohalite ion is at least one selected from the group consisting of hypochlorite ions and hypobromite ions. The hypohalite ion functions as an oxidizing agent for high-melting-point metals. The concentration of the hypohalite ion is 0.0001 mol / L or more and 3.0 mol / L or less. When the concentration of the hypohalite ion is 3.0 mol / L or less, the decomposition of the hypohalite ion is suppressed, and its function as an oxidizing agent is fully exhibited. When the concentration of the hypohalite ion is 0.0001 mol / L or more, the etching rate of high-melting-point metals becomes sufficient.

[0027] In this embodiment, the concentration of hypohalite ions in the treatment solution is preferably 0.001 mol / L to 1.0 mol / L, and more preferably 0.005 mol / L to 0.5 mol / L, relative to the total volume of the treatment solution, from the standpoint of the stability of the treatment solution and the ability to dissolve high-melting-point metals. One type of hypohalite ion may be used, or two or more types of hypohalite ions may be used. When two or more types of hypohalite ions are contained in the treatment solution, it is preferable that the total concentration of all hypohalite ions is within the above range.

[0028] The cation paired with the hypohalite ion can be selected from inorganic or organic cations. Examples of inorganic cations include at least one selected from the group consisting of sodium ions, potassium ions, and calcium ions. Examples of organic cations include at least one selected from the group consisting of quaternary ammonium salts, quaternary phosphonium salts, and quaternary arsonium salts, with quaternary ammonium salts being preferred due to the ease of obtaining semiconductor-grade cations. Furthermore, from the viewpoint of the stability of the hypohalite ion, examples of quaternary ammonium salts include at least one selected from the group consisting of tetramethylammonium ions, tetraethylammonium ions, tetrapropylammonium ions, and tetrabutylammonium ions, with tetramethylammonium ions being more preferred. The method for incorporating hypohalite ions into the treatment solution is not particularly limited, but examples include adding a hypohalite salt, adding chlorine or bromine to an alkaline solution, or, in the case of hypobromite ions, generating hypobromite ions by adding a bromine-containing compound and an oxidizing agent. Examples of hypohalite salts include salts of hypohalous acid and at least one selected from the group consisting of the inorganic and organic cations mentioned above. Examples of alkaline solutions include at least one selected from the group consisting of aqueous sodium hydroxide solution, aqueous potassium hydroxide solution, and aqueous tetramethylammonium solution. More specifically, in the case of hypochlorite ions, one method is to generate them by mixing chlorine gas with an organic alkali (e.g., aqueous tetramethylammonium solution) and neutralizing it. In the case of hypobromite ions, one method is to generate them by mixing bromine with an organic alkali (e.g., aqueous tetramethylammonium solution) and neutralizing it, or by mixing a bromine-containing compound with an oxidizing agent (e.g., containing hypochlorite ions) and oxidizing the bromide ions with hypochlorite ions to generate hypobromite ions.

[0029] (Chloride ions or bromide ions) The treatment solution of this embodiment may contain chloride ions or bromide ions to the extent that it does not impair the objective of the present invention. When the treatment solution contains hypochlorite ions, it is preferable that it contains chloride ions, and when the treatment solution contains hypobromite ions, it is preferable that it contains bromide ions.

[0030] Chloride ions can be incorporated into the treatment solution by adding, for example, chlorine gas, hydrogen chloride, or chloride salts. The amount of chloride ions can be adjusted by the mass of chlorine gas, hydrogen chloride, or chloride salts added relative to the treatment solution. The hypohalite ions contained in the treatment solution are hypochlorite ions, which are generated by neutralization of chlorine gas with an organic alkali (e.g., Cl ２ +2TMAH→TMAClO+TMACl+H ２ In formula O, TMA represents tetramethylammonium. As shown in the chemical formula, the treatment solution may contain at least the same amount of chloride ions as the generated hypochlorite ions. The hypohalite ions contained in the treatment solution are hypobromite ions, and the hypobromite ions are generated by oxidizing bromide ions with hypochlorite ions (e.g., ClO ― +Br ― →BrO ― +Cl ― In this case, as shown in the chemical formula, the treatment solution may contain at least equimolar amounts of chloride ions with respect to the generated hypobromite ions. When the amount of bromide ions added relative to the hypochlorite ions is small, hypochlorite ions and hypobromite ions will be present simultaneously, and the treatment solution may contain equimolar amounts of chloride ions with respect to the remaining hypochlorite ions, and equimolar amounts of chloride ions with respect to the generated hypobromite ions.

[0031] Bromide ions can be incorporated into the treatment solution by adding, for example, bromine gas, hydrogen bromide, or bromide salts. The amount of bromide ions can be adjusted by the mass of bromine gas, hydrogen bromide, or bromide salts added to the treatment solution. The hypohalite ions contained in the treatment solution are hypobromite ions, which are produced by the neutralization of bromine with an organic alkali (e.g., Br). ２+2TMAH→TMABrO+TMABr+H ２ O) In this case, the treatment solution may contain at least a molar amount of bromide ions equivalent to hypobromite ions.

[0032] The concentration of chloride ions or bromide ions is not particularly limited as long as it does not deviate from the purpose of the present invention, but is preferably 0.0001 mol / L or more and 5.0 mol / L or less. When the concentration of chloride ions or bromide ions is 5.0 mol / L or less, copper corrosion can be suppressed. When the concentration of chloride ions or bromide ions is 0.0001 mol / L or more, the removal rate (etching rate) of high-melting-point metals becomes sufficient. From the viewpoint of suppressing copper corrosion and the etching rate of high-melting-point metals, the concentration of chloride ions or bromide ions contained in the removal treatment solution is preferably 0.001 mol / L or more and 3.0 mol / L or less, and more preferably 0.005 mol / L or more and 1.0 mol / L or less, relative to the total volume of the treatment solution.

[0033] Furthermore, two types of chloride ions or bromide ions may be present in the treatment solution. In this case, the total concentration of chloride ions and bromide ions is preferably 0.0001 mol / L or more and 5.0 mol / L or less, and more preferably 0.001 mol / L or more and 3.0 mol / L or less.

[0034] (Halogenated oxygen ions) The treatment solution of this embodiment may contain halogenated oxygen ions other than hypohalite ions, to the extent that it does not impair the objective of the present invention. Specifically, halogenated oxygen ions other than hypohalite include one or more selected from the group consisting of chlorate ions, chlorite ions, bromate ions, and bromite ions.

[0035] Chlorate ions can be incorporated into the treatment solution by, for example, adding chloric acid or chlorate salts. Furthermore, the amount of chlorate ions can be adjusted by the amount of chloric acid or chlorate salts added relative to the treatment solution.

[0036] Chlorite ions can be incorporated into the treatment solution by adding, for example, chlorous acid or chlorite salts. Furthermore, the amount of chlorite ions can be adjusted by the amount of chlorous acid or chlorite salts added relative to the treatment solution.

[0037] The bromate ion can be contained in the treatment liquid by adding, for example, bromic acid or a bromate. Further, its content can be adjusted by the mass of bromic acid or the bromate added to the treatment liquid.

[0038] The bromite ion can be contained in the treatment liquid by adding, for example, bromous acid or a bromite. Further, its content can be adjusted by the mass of bromous acid or the bromite added to the treatment liquid.

[0039] The concentration of the halogen oxyacid ion other than the hypohalite ion is not particularly limited as long as the object of the present invention is not deviated, but it is preferably 0.1 mmol / L or more and 1.0 mol / L or less. When the concentration of the halogen oxyacid ion other than the hypohalite ion is 1.0 mol / L or less, the corrosion of copper can be suppressed. When the concentration of the halogen oxyacid ion other than the hypohalite ion is 0.1 mmol / L or more, the corrosion of copper can be suppressed.

[0040] The halogen oxyacid ion other than the hypohalite ion contained in the treatment liquid of the present embodiment is more preferably 1.0 mmol / L or more and 0.5 mol / L or less, and further preferably 10.0 mmol / L or more and 0.1 mol / L or less, based on the total volume of the treatment liquid, from the viewpoints of suppressing the corrosion of copper and the etching rate of the high melting point metal. Further, two or more kinds of halogen oxyacid ions other than the hypohalite ion may be contained in the treatment liquid. In this case, the total concentration of the halogen oxyacid ions other than the hypohalite ion is preferably 1.0 mmol / L or more and 0.5 mol / L or less, and more preferably 10 mmol / L or more and 0.1 mol / L or less.

[0041] (Alkali metals and alkaline earth metals) The treatment liquid of the present embodiment may contain one or more metals selected from the group consisting of alkali metals and alkaline earth metals. Specifically, as the alkali metal, at least one selected from the group consisting of Na, K, and Rb is preferable. Specifically, as the alkaline earth metal, at least one selected from the group consisting of Mg, Ca, and Sr is preferable. The alkali metals and alkaline earth metals function as oxidation accelerators for high melting point metals. It is presumed that the form of these metals present in the treatment liquid is in the state of metal ions. The concentration thereof is not particularly limited as long as the object of the present invention is not deviated, but it is preferably 1 ppm by mass or more and 10.0% by mass or less with respect to the total mass of the treatment liquid. When the concentration of the alkali metal or alkaline earth metal is 10.0% by mass or less, the decomposition of hypohalite ions is suppressed, which is preferable from the viewpoint of the stability of hypohalite ions. Further, when the concentration is 1 ppm by mass or more, the oxidation accelerating effect of the high melting point metal can be sufficiently obtained. The alkali metal or alkaline earth metal contained in the treatment liquid of the present embodiment is more preferably 0.001% by mass or more and 5.0% by mass or less, and further preferably 0.01% by mass or more and 1.0% by mass or less with respect to the total mass of the treatment liquid, from the viewpoints of the stability of the treatment liquid and the oxidation accelerating effect of the high melting point metal.

[0042] Further, two or more of these alkali metals and alkaline earth metals may be contained in the treatment liquid. In this case, the total concentration of the alkali metal and alkaline earth metal is preferably 1 ppm by mass or more and 10.0% by mass or less, more preferably 0.001% by mass or more and 5.0% by mass or less, and further preferably 0.01% by mass or more and 1.0% by mass or less.

[0043] Methods for incorporating alkali metals or alkaline earth metals into the treatment solution include adding alkali metal or alkaline earth metal salts, specifically alkali metal or alkaline earth metal fluorides, chlorides, bromides, iodides, or hydroxides, to the treatment solution, as described later. It is preferable to add alkali metal or alkaline earth metal hydroxides to the treatment solution. That is, it is preferable that the treatment solution contains one or more metals selected from the group consisting of alkali metals and alkaline earth metals, and hydroxide ions.

[0044] (Solvent) Examples of solvents for the processing solution in this embodiment include water and organic solvents, with water being the most preferred. The water contained in the processing solution is preferably water from which metal ions, organic impurities, and particle particles have been removed by distillation, ion exchange treatment, filtration treatment, various adsorption treatments, etc., and pure water or ultrapure water is particularly preferred.

[0045] The amount of solvent is not particularly limited and can be adjusted as appropriate so that the concentration of the oxidizing agent, etc., in the treatment solution reaches the desired concentration.

[0046] (pH) The pH of the treatment solution in this embodiment is 7.0 to 14.0. When the pH is 7.0 or higher, the storage stability of the hypohalite ions is good. When the pH is 14.0 or lower, the etching rate for high-melting-point metals is sufficient. Storage stability refers to the evaluation of the change in the concentration of hypohalite ions when the treatment solution is stored for a long period of time. From the viewpoint of the dissolving ability of high-melting-point metals and the storage stability of the treatment solution, the pH of the treatment solution is preferably 9.0 to 13.0, and more preferably 11.0 to 13.0. Note that the pH values ​​here are at 25°C.

[0047] Acids or bases can be used to adjust the pH of the treatment solution. Examples of bases include inorganic bases (inorganic alkalis) and organic bases (organic alkalis). Inorganic bases consist of metal ions and hydroxide ions, and specifically include one or more selected from the group consisting of sodium hydroxide, potassium hydroxide, magnesium hydroxide, and calcium hydroxide.

[0048] An organic base consists of an organic cation and a hydroxide ion. Exemplifying the organic cation, it is an onium ion. An onium ion is a compound of a polyatomic cation formed by adding an excess of protons (hydrogen cations) to a monoatomic anion. Specifically, it is one or more cations selected from the group consisting of imidazolium ion, pyrrolidinium ion, pyridinium ion, piperidinium ion, ammonium ion, phosphonium ion, fluoronium ion, chloronium ion, bromonium ion, iodonium ion, oxonium ion, sulfonium ion, selenonium ion, telluronium ion, arsonium ion, stibonium ion, and bismuthonium ion. Among them, ammonium ion, phosphonium ion, and sulfonium ion are stably present in an alkaline solution, can easily modify the carbon chain and functional groups contained in the onium ion, and can easily control solubility, bulkiness, and charge density. Therefore, they are suitable as the organic cation contained in the organic alkali of this embodiment.

[0049] From the viewpoint of being industrially mass-produced at a low cost, ammonium ion is more suitable as the onium ion. Exemplifying such ammonium ions, they are tetraalkylammonium ions, and more preferably, one or more selected from the group consisting of tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, and tetrabutylammonium ion. An organic alkali containing an onium ion and a hydroxide ion, that is, hydroxide onium, can be preferably used as an organic alkali. Also, an organic alkali containing ammonium ion (NH ４ ＋ ) or 2-hydroxyethyltrimethylammonium as an organic cation can also be preferably used as the organic alkali of this embodiment.

[0050] The organic alkali is particularly preferably tetraalkylammonium hydroxide. Examples of tetraalkylammonium hydroxide include one or more selected from the group consisting of tetramethylammonium hydroxide, ethyltrimethylammonium hydroxide, tetraethylammonium hydroxide, propyltrimethylammonium hydroxide, tetrapropylammonium hydroxide, butyltrimethylammonium hydroxide, and tetrabutylammonium hydroxide.

[0051] Examples of acids include inorganic acids and organic acids. Specific examples of inorganic acids include one or more selected from the group consisting of hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, boric acid, and hydrofluoric acid. Specific examples of organic acids include one or more selected from the group consisting of formic acid, acetic acid, methanesulfonic acid, and benzoic acid.

[0052] (Other) The processing solution in this embodiment contains alkali metals and non-alkali metals, specifically aluminum, iron, chromium, manganese, nickel, zinc, and lead. These metals may be introduced during the manufacturing process, leaching from the container, or from the environment. Since these metals may negatively affect the stability of hypohalite ions, the content of each metal is preferably 1 ppm by mass or less, more preferably 200 ppt by mass or less, and most preferably 100 ppt by mass or less.

[0053] The processing solution of this embodiment may contain other additives that have been conventionally used in semiconductor processing solutions, as long as they do not impair the objectives of the present invention. For example, other additives that can be added include acids, metal corrosion inhibitors, water-soluble organic solvents, fluorine compounds, reducing agents, complexing agents, chelating agents, surfactants, defoaming agents, buffering agents, and stabilizers. These additives may be added individually or in combination.

[0054] When the processing solution in this embodiment contains water as a solvent, the water contained in the processing solution is preferably water from which metal ions, organic impurities, and particle particles have been removed by distillation, ion exchange treatment, filtration treatment, or various adsorption treatments, and pure water or ultrapure water is particularly preferred. Such water can be obtained by known methods widely used in semiconductor manufacturing.

[0055] In this embodiment, the treatment solution is preferably stored at a low temperature and / or protected from light. Storing it at a low temperature and / or protected from light is expected to suppress the decomposition of the oxidizing agent in the treatment solution. Furthermore, storing the treatment solution in a container filled with an inert gas prevents the incorporation of carbon dioxide, thereby maintaining the stability of the treatment solution. In addition, the inner surface of the container, i.e., the surface in contact with the treatment solution, is preferably made of glass or an organic polymer material. This is because the incorporation of impurities such as metals, metal oxides, and organic substances can be further reduced by making the inner surface of the container out of glass or an organic polymer material.

[0056] (Method for Processing Semiconductor Substrates) A ​​processing method according to one embodiment of the present invention is a method for processing a semiconductor substrate containing a high-melting-point metal and copper, and is a processing method that removes the high-melting-point metal using a semiconductor processing solution according to one embodiment of the present invention. Specifically, a method is given in which the high-melting-point metal on the substrate is etched by bringing the processing solution into contact with the substrate. By using the processing solution according to one embodiment, it is possible to etch, for example, a high-melting-point metal film formed on a substrate used for semiconductors. Furthermore, it is possible to selectively etch the high-melting-point metal on a substrate in which both the high-melting-point metal and copper are present, and to suppress galvanic corrosion of copper.

[0057] (Semiconductor Substrate) The high-melting-point metal contained in the semiconductor substrate exists as a film deposited on the semiconductor substrate, for example, as a liner layer. Copper also exists on the semiconductor substrate or liner layer, for example, as wiring. The semiconductor substrate is not limited as long as it contains the high-melting-point metal and copper, and the processing method according to one embodiment of the present invention can be applied to known substrates used for semiconductors. Examples include various substrates such as semiconductor wafers, glass substrates, or organic resin substrates.

[0058] (High Melting Point Metals) In this specification, high melting point metals are metals with a melting point of 1400°C or higher. Specifically, examples include one or more metals selected from the group consisting of titanium, tantalum, ruthenium, molybdenum, tungsten, chromium, iridium, rhodium, platinum, and niobium. High melting point metals preferably contain ruthenium, molybdenum, or tungsten, and most preferably contain ruthenium. The above metals may also include alloys, oxides, nitrides, oxynitrides, etc., containing these metallic elements.

[0059] (Etching of Semiconductor Substrates) The processing solution according to one embodiment of the present invention can be used for etching semiconductor substrates. The etching process includes the step of bringing a semiconductor substrate into contact with the processing solution according to one embodiment of the present invention. As an example of an etching process using the processing solution, a wet etching process of ruthenium will be described. First, a substrate made of a semiconductor (for example, Si) is prepared. The prepared substrate is subjected to silicon oxidation treatment to form a silicon oxide film on the substrate. Then, an interlayer insulating film made of a low dielectric constant (Low-k) film is deposited to form via holes at predetermined intervals. After the via holes are formed, ruthenium is deposited by thermochemical vapor deposition (CVD). Then, copper is deposited on the ruthenium film by electroplating. Then, the copper is polished by chemical mechanical polishing (CMP). Then, by etching the excess ruthenium film by immersion in the processing solution according to one embodiment of the present invention, it becomes possible to selectively etch the ruthenium without corroding or etching the copper.

[0060] A ratio of the etching rate of a high-melting-point metal to the etching rate of copper (etching rate of high-melting-point metal / etching rate of copper) of 50 or more is preferable in semiconductor manufacturing processes. A ratio of 80 or more is more preferable, and a ratio of 100 or more is even more preferable.

[0061] The temperature used when etching high-melting-point metals with a processing solution is not particularly limited, but should be determined considering the etching rate of the high-melting-point metal. At high processing temperatures, the stability of hypohalite ions decreases. On the other hand, at lower temperatures, the etching rate tends to decrease. For these reasons, the etching temperature for high-melting-point metals is preferably 10°C to 90°C, more preferably 15°C to 60°C, and most preferably 20°C to 50°C.

[0062] The time for contact between the processing solution and the semiconductor substrate is in the range of 0.1 to 60 minutes, preferably 0.5 to 30 minutes, and more preferably 1 to 10 minutes, and can be appropriately selected depending on the etching conditions and the cleaning equipment used. As a rinsing solution after using the processing solution, a suitable solution can be selected that can remove etching residue, metal-derived particles and organic matter in the processing solution without corroding the metal on the substrate. Examples include one or more selected from the group consisting of ultrapure water, isopropyl alcohol, ammonia water, hydrofluoric acid, hydrochloric acid, hydrogen peroxide, acetic acid, sulfuric acid, ozonated water, hydrogen water, a mixture of hydrofluoric acid and hydrogen peroxide, a mixture of sulfuric acid and hydrogen peroxide, a mixture of ammonia water and hydrogen peroxide, and a mixture of hydrochloric acid and hydrogen peroxide.

[0063] <Method for Manufacturing a Semiconductor Substrate> Another embodiment of the present invention is a method for manufacturing a semiconductor substrate, which includes the semiconductor substrate processing method described above. The method for manufacturing a semiconductor substrate may include known processes used in the manufacturing of a semiconductor substrate, such as, in addition to the etching process described above, one or more processes selected from a wafer manufacturing process, an oxide film formation process, a transistor formation process, a wiring formation process, and a CMP process. In the manufacturing method of this embodiment, a semiconductor substrate can be manufactured that contains a metal described above as a high-melting-point metal and a metal whose corrosion potential becomes higher than that of the high-melting-point metal when in contact with the processing solution, such as copper. An example of a specific wiring formation process will be described with reference to Figure 1. First, a substrate 11 having via holes is prepared, and a layer made of a high-melting-point metal is formed on the substrate as a seed layer 13. A resist 12 is provided on a predetermined part of the substrate 11, and then a copper layer 14 is applied by an operation such as electroplating. After planarizing the metal by chemical mechanical polishing, a process is performed to remove the resist 12, and a part of the seed layer 13 made of a high-melting-point metal is removed by etching with the processing solution. According to the semiconductor substrate manufacturing method of this embodiment, high-melting-point metals (e.g., ruthenium) can be selectively removed from copper during the etching process.

[0064] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0065] (Method for calculating hypochlorite ion concentration and hypobromite ion concentration) The concentrations of hypochlorite ions and hypobromite ions were measured using a UV-Vis spectrophotometer (UV-2600, manufactured by Shimadzu Corporation). Calibration curves were created using hypobromite ion and hypochlorite ion aqueous solutions of known concentration, and the concentrations of hypochlorite ions and hypobromite ions in the prepared treatment solution were determined. The concentrations of hypochlorite ions and hypobromite ions were obtained from measurement data after the absorption spectrum stabilized following the preparation of the treatment solution.

[0066] (Method for determining the concentration of carboxylic acids) The concentration of carboxylic acids was measured using HPLC (alliance HPLC system, Waters). Calibration curves were created using aqueous solutions of each compound with known concentrations, and the concentration of carboxylic acids in the prepared treatment solution was determined.

[0067] (Method for determining alkali metal and alkaline earth metal concentrations) The concentrations of alkali metals and alkaline earth metals in the treatment solution were analyzed using a high-frequency inductively coupled plasma emission spectrometer (iCAP6500DuO, Thermo SCIENTIFIC). After diluting each treatment solution to an appropriate concentration with ultrapure water, nitric acid (Kanto Chemical Co., Ltd., Ultrapure) was added to adjust the pH to 1 or less. The adjusted treatment solutions were then introduced into the instrument, and the metal concentrations were analyzed.

[0068] (Method for Quantitative Determination of Tetramethylammonium Ions) The concentration of tetramethylammonium ions in the treatment solution was analyzed using cation chromatography (Integrion, Thermo Fisher Scientific). After preparation, an equal amount of 30% hydrogen peroxide (for volumetric analysis, Fujifilm Wako Pure Chemical Industries, Ltd.) was added to each treatment solution, and then diluted to an appropriate concentration with ultrapure water. After confirming that the hypohalite ions had been completely decomposed by the hydrogen peroxide using the methods for calculating the hypochlorite ion concentration and hypobromite ion concentration described above, the treatment solution was introduced into the apparatus and the tetramethylammonium ion concentration was measured.

[0069] (Method for determining halogen oxygen ions other than hypohalite) The concentration of halogen oxygen ions other than hypohalite in the treatment solution was analyzed using anion chromatography (Integrion, Thermo Fisher Scientific). After preparation, an equal amount of 30% hydrogen peroxide (for volumetric analysis, Fujifilm Wako Pure Chemical Industries, Ltd.) was added to each treatment solution, and then diluted to an appropriate concentration with ultrapure water. After confirming that the hypohalite ions had been completely decomposed by hydrogen peroxide using the above-mentioned method for calculating the hypochlorite ion concentration and hypobromite ion concentration, this treatment solution was introduced into the apparatus and halogen oxygen ions other than hypohalite were measured.

[0070] (pH Measurement Method) The pH of 10 mL of the treatment solution prepared in the Examples and Comparative Examples was measured using a benchtop pH meter (LAQUA F-73, manufactured by Horiba, Ltd.). Before measuring the treatment solution, the pH was calibrated using a neutral phosphate pH standard solution (pH 6.86, manufactured by Kanto Chemical Co., Ltd.), a borate pH standard solution (pH 9.18, manufactured by Kanto Chemical Co., Ltd.), and a pH 13.00 standard solution (manufactured by Hanna Instruments). pH measurement was performed after the treatment solution was prepared and stabilized at 25 ± 1°C.

[0071] (Evaluation) Using the prepared treatment solution, the etching rate of ruthenium, the etching rate of copper, and the galvanic corrosion of copper were evaluated by the method described later.

[0072] (Etching rate of ruthenium) An oxide film was formed on a silicon wafer using a batch-type thermal oxidation furnace, and ruthenium was deposited on it using the sputtering method to a thickness of 1200 Å (±10%). The sheet resistance of the ruthenium was measured using a four-probe resistance meter (Lorestar-GP, manufactured by Mitsubishi Chemical Analytec Co., Ltd.) and converted to film thickness, which was used as the ruthenium film thickness before etching. 40 mL of the treatment solution was prepared in a fluororesin container with a lid (AsOne Co., Ltd., PFA container, 94.0 mL). A 10 × 10 mm ruthenium film piece cut from the wafer with the 1200 Å ruthenium film was immersed in the treatment solution at a predetermined temperature for 2 minutes to obtain the ruthenium film after treatment. The film thickness of the ruthenium film after treatment was measured according to the method described above, and the etching rate was obtained by dividing the difference in film thickness before and after treatment by the treatment time. The etching rate of ruthenium was evaluated according to the following evaluation criteria. A: 200 Å / min or more B: 100 Å / min or more but less than 200 Å / min C: 50 Å / min or more but less than 100 Å / min D: Less than 50 Å / min

[0073] (Evaluation of the Stability of Ruthenium Etching Rate) A 10 × 10 mm ruthenium film piece, cut from a wafer coated with a 1200 Å ruthenium film using the method described above, was immersed in a 25°C treatment solution for 2 minutes. The ruthenium film thickness was measured according to the method described above and was defined as the film thickness after etching. This was defined as the etching rate immediately after the preparation of the treatment solution, and the etching rate was evaluated every week thereafter using the method described above. The number of days in which the obtained etching rate increased or decreased within ±20% of the etching rate immediately after the preparation of the treatment solution was defined as the etching rate stability (days), and was evaluated according to the following criteria: A: 180 days or more B: 120 days or more and 179 days or less C: 60 days or more and 119 days or less D: 59 days or less

[0074] (Copper Etching Rate) 40 mL of the treatment solution was prepared in a lidded fluoropolymer container (AsOne, PFA container, 94.0 mL). A 10 mm × 10 mm copper film piece, cut from a wafer with a 200 Å thick copper film, was immersed in the treatment solution at a predetermined temperature for 1 hour. The copper dissolved in the solution was analyzed using a high-frequency inductively coupled plasma atomic emission spectrometer (iCAP6500DuO, Thermo SCIENTIFIC). The amount of dissolved copper obtained was calculated using the copper density of 8.96 g / cm³. ３ The amount of elution converted to film thickness was then divided by the processing time to determine the etching rate of copper. Copper corrosion was evaluated according to the following criteria: A: Less than 1 Å / min B: 1 Å / min or more and 10 Å / min or less C: Greater than 10 Å / min

[0075] (Evaluation of the copper surface after etching) An oxide film was formed on a silicon wafer using a batch-type thermal oxidation furnace, and copper was deposited on it using the sputtering method to a thickness of 200 Å (±10%). 40 mL of the processing solution was prepared in a lidded fluororesin container (AsOne, PFA container, 94.0 mL). A 10 mm × 10 mm copper film piece, cut from the wafer with the 200 Å copper film, was immersed in the processing solution at 25°C for 2 minutes, then washed with ultrapure water to obtain the copper film after etching. The surface of the obtained etched copper film was observed using a field emission scanning electron microscope (JSM-7800F Prime, JEOL Ltd.) and evaluated according to the following criteria: A: No residue B: Some residue C: Partial residue D: Residue throughout

[0076] (Evaluation of galvanic corrosion of copper) An oxide film was formed on a silicon wafer using a batch-type thermal oxidation furnace, and then a ruthenium film with a thickness of 1200 Å (±10%) and a copper film with a thickness of 200 Å (±10%) were deposited on top of it using the sputtering method. The Taffel plot of each wafer in the processing solution was measured using a potentiostat (AMETEK, VersaSTAT 3F) to determine the corrosion potential. For the potentiostat electrodes, each wafer was used as the working electrode, a Pt wire as the counter electrode, and a silver / silver chloride electrode as the reference electrode. The corrosion potential difference was calculated using the following formula: Corrosion potential difference = (Corrosion potential of copper) - (Corrosion potential of ruthenium) The galvanic corrosion of copper was evaluated according to the following evaluation criteria: A: 0 mV or more B: -50 mV or more and less than 0 mV C: Less than -50 mV

[0077] <Examples 1-3> Treatment solutions were prepared as follows to have the compositions shown in Table 1. The treatment solution was obtained by adding glycolic acid (manufactured by Fujifilm Wako Pure Chemical Industries), sodium hypochlorite pentahydrate (Nikkei Diasodium Pentahydrate, manufactured by Nippon Light Metal Co., Ltd.), ultrapure water, 10% sodium hydroxide (Kagoshima Special Grade, manufactured by Kanto Chemical Co., Ltd.), and sodium chloride (99.999%, manufactured by Sigma-Aldrich). The evaluations shown in Table 1 were performed using the obtained treatment solution.

[0078] <Example 4> As shown in Figure 2, a 25% by mass aqueous solution of tetramethylammonium hydroxide (SD-25, manufactured by Tokuyama Corporation) and ultrapure water were mixed in a 2 L glass three-necked flask 21 (manufactured by Cosmosbead Co., Ltd.) to obtain a 0.63 mol / L aqueous solution of tetramethylammonium hydroxide. Next, a rotor 24 (manufactured by AsOne, 30 mm in length x 8 mm in diameter) was placed inside the three-necked flask 21. A thermometer protection tube 22 (manufactured by Cosmosbead, bottom sealed type) and a thermometer 23 were placed into one opening. A chlorine gas cylinder and a nitrogen gas cylinder were connected to the other opening, allowing for switching between chlorine gas and nitrogen gas as needed. The tip of a PFA tube 25 (manufactured by Flon Industries, F-8011-02) was immersed in the bottom of the solution. The remaining opening was connected to a gas washing bottle 26 (manufactured by AsOne, gas washing bottle, model number 2450 / 500) filled with a 5% by mass sodium hydroxide aqueous solution 27. Subsequently, a magnetic stirrer (AsOne, C-MAG HS10) was placed at the bottom of the three-necked flask 21 and rotated at 300 rpm for stirring. While cooling the outer circumference of the three-necked flask with ice water 20, chlorine gas (purity 99.999 or higher, ADEKA) was supplied at a flow rate of 38 mL / min. The resulting tetramethylammonium hypochlorite aqueous solution had a concentration of 0.31 mol / L and a pH of 12.0. To the obtained tetramethylammonium hypochlorite aqueous solution, glycolic acid, a 25% by mass aqueous solution of tetramethylammonium hydroxide, and ultrapure water were added to obtain the treatment solutions listed in Table 1. The evaluations listed in Table 1 were performed using the obtained treatment solutions. In Figure 2, reference numeral 28 indicates a flow meter and reference numeral 29 indicates a water bath.

[0079] <Example 5> As shown in Figure 3, a nitrogen cylinder was connected to one end of a 100 mL PFA trap bottle 16 (manufactured by Flon Chemical Co., Ltd.) so that nitrogen gas could be supplied. The other end was connected to a 500 mL PFA trap bottle 17 (manufactured by Flon Chemical Co., Ltd.). 20 mL of bromine (purity > 98%, manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the 100 mL PFA trap bottle 16. At this time, it was confirmed that the tip of the PFA tube 19 was not in contact with the liquid bromine. A 10% sodium hydroxide aqueous solution (special grade, manufactured by Kanto Chemical Co., Ltd.) and ultrapure water were added to the 500 mL PFA trap bottle 17 to obtain a 0.34 mol / L sodium hydroxide aqueous solution. Next, a stirring bar 18 was added to the 500 mL PFA trap bottle 17. A magnetic stirrer (AsOne, C-MAG HS10) was placed at the bottom of a 500 mL PFA trap bottle 17 and rotated at 300 rpm for stirring. Nitrogen was supplied to a 100 mL PFA trap bottle 16 at a flow rate of 100 cc / min, and the gasified bromine was supplied to the subsequent 500 mL PFA trap bottle 17 for 300 minutes to obtain a 0.12 mol / L sodium hypobromite aqueous solution with a pH of 12.0. To the obtained sodium hypobromite aqueous solution, glycolic acid, a 10% sodium hydroxide aqueous solution, and ultrapure water were added to obtain the treatment solution shown in Table 1. The evaluations shown in Table 1 were performed using the obtained treatment solution. Note that reference numeral 15 in Figure 3 indicates a flow meter.

[0080] <Example 6> Tetramethylammonium hypobromite aqueous solution was obtained in the same manner as in Example 5, except that the liquid used to blow in bromine gas was changed from a 0.34 mol / L sodium hydroxide aqueous solution to a 0.34 mol / L tetramethylammonium hydroxide aqueous solution so that the composition was as shown in Table 1. Glycolic acid, tetramethylammonium hydroxide aqueous solution, and ultrapure water were added to the obtained tetramethylammonium hypobromite aqueous solution to obtain the treatment solution shown in Table 1. The evaluations shown in Table 1 were performed using the obtained treatment solution.

[0081] <Examples 7-12> Treatment solutions were obtained in the same manner as in Examples 1-6, except that lactic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used instead of glycolic acid as the carboxylic acid to obtain the composition shown in Table 1. The evaluations shown in Table 1 were performed using the obtained treatment solutions.

[0082] <Examples 13-18> Treatment solutions were obtained in the same manner as in Example 2, except that citric acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of glycolic acid as the carboxylic acid to obtain the composition shown in Table 1. The evaluations shown in Table 1 were performed using the obtained treatment solutions.

[0083] <Example 19> A treatment solution was obtained in the same manner as in Example 2, except that malic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of glycolic acid as the carboxylic acid to obtain the composition shown in Table 1. The evaluations shown in Table 1 were performed using the obtained treatment solution.

[0084] <Example 20> A treatment solution was obtained in the same manner as in Example 2, except that tartaric acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of glycolic acid as the carboxylic acid to obtain the composition shown in Table 1. The evaluations shown in Table 1 were performed using the obtained treatment solution.

[0085] <Example 21> A treatment solution was obtained in the same manner as in Example 2, except that glyceric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used instead of glycolic acid as the carboxylic acid to obtain the composition shown in Table 1. The evaluations shown in Table 1 were performed using the obtained treatment solution.

[0086] <Example 22> A treatment solution was obtained in the same manner as in Example 2, except that oxalacetic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of glycolic acid as the carboxylic acid to obtain the composition shown in Table 1. The evaluations shown in Table 1 were performed using the obtained treatment solution.

[0087] <Example 23> A treatment solution was obtained in the same manner as in Example 2, except that oxalic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of glycolic acid as the carboxylic acid to obtain the composition shown in Table 1. The evaluations shown in Table 1 were performed using the obtained treatment solution.

[0088] <Example 24> A treatment solution was obtained in the same manner as in Example 2, except that malonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of glycolic acid as the carboxylic acid to obtain the composition shown in Table 1. The evaluations shown in Table 1 were performed using the obtained treatment solution.

[0089] <Example 25> A treatment solution was obtained in the same manner as in Example 2, except that succinic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of glycolic acid as the carboxylic acid to obtain the composition shown in Table 1. The evaluations shown in Table 1 were performed using the obtained treatment solution.

[0090] <Example 26> A treatment solution was obtained in the same manner as in Example 2, except that 1,2,3,4-butanetetracarboxylic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of glycolic acid as the carboxylic acid to obtain the composition shown in Table 1. The evaluations shown in Table 1 were performed using the obtained treatment solution.

[0091] <Example 27> A treatment solution was obtained in the same manner as in Example 2, except that glycolic acid and lactic acid were used as carboxylic acids to achieve the composition shown in Table 1. The evaluations shown in Table 1 were performed using the obtained treatment solution.

[0092] <Example 28> A treatment solution was obtained in the same manner as in Example 2, except that glycolic acid and citric acid were used as carboxylic acids to achieve the composition shown in Table 1. The evaluations shown in Table 1 were performed using the obtained treatment solution.

[0093] <Example 29> A treatment solution was obtained in the same manner as in Example 2, except that lactic acid and citric acid were used instead of glycolic acid as carboxylic acids to obtain the composition shown in Table 1. The evaluations shown in Table 1 were performed using the obtained treatment solution.

[0094] <Example 30> A treatment solution was obtained in the same manner as in Example 2, except that citric acid and malic acid were used instead of glycolic acid as carboxylic acids to obtain the composition shown in Table 1. The evaluations shown in Table 1 were performed using the obtained treatment solution.

[0095] <Example 31> A treatment solution was obtained in the same manner as in Example 2, except that 2-methoxybenzoic acid was used instead of glycolic acid as the carboxylic acid to obtain the composition shown in Table 1. The evaluations shown in Table 1 were performed using the obtained treatment solution.

[0096] <Example 32> A treatment solution was obtained in the same manner as in Example 5, except that 2-methoxybenzoic acid was used instead of glycolic acid as the carboxylic acid to obtain the composition shown in Table 1. The evaluations shown in Table 1 were performed using the obtained treatment solution.

[0097] <Example 33> First, treatment solution A containing 0.1 mol / L sodium hypochlorite was obtained in the same manner as in Example 2, except that glycolic acid was not used and the amount of sodium hypochlorite pentahydrate was doubled. Next, treatment solution B was prepared containing 0.05 mol / L sodium bromide and 0.02 mol / L 2-methoxybenzoic acid, and having the same pH as treatment solution A. Finally, the prepared treatment solutions A and B were mixed in a 1:1 volume ratio. The sodium hypochlorite contained in treatment solution A oxidized the sodium bromide contained in treatment solution B, generating sodium hypobromite (NaClO + NaBr → NaBrO + NaCl). At this time, in the mixed treatment solution, the concentration of sodium bromide is half that of sodium hypochlorite. Therefore, of the 0.05 mol / L sodium hypochlorite, 0.025 mol / L sodium hypochlorite and 0.025 mol / L sodium bromide react to produce 0.025 mol / L sodium hypobromite. Thus, a treatment solution can be obtained in which the 0.025 mol / L sodium hypochlorite that was not used in the reaction and the 0.025 mol / L sodium hypobromite produced by the reaction coexist. Through this process, a treatment solution with the composition shown in Table 1 was obtained. The evaluations shown in Table 1 were performed using the obtained treatment solution.

[0098] <Comparative Example 1> A treatment solution was obtained in the same manner as in Example 5, except that a carboxylic acid was not added to achieve the composition shown in Table 1. The evaluations shown in Table 1 were performed using the obtained treatment solution.

[0099] <Comparative Example 2> A treatment solution was obtained by adding a 10% sodium hydroxide aqueous solution and ultrapure water to citric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to obtain the composition shown in Table 1. The evaluations shown in Table 1 were performed using the obtained treatment solution.

[0100] <Comparative Example 3> A treatment solution was obtained in the same manner as in Example 5, except that benzotriazole (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used instead of glycolic acid to obtain the composition shown in Table 1. The evaluations shown in Table 1 were performed using the obtained treatment solution. In the table, TMA represents tetramethylammonium.

[0101] As is clear from the results shown in Table 1, by treating a semiconductor substrate with a semiconductor processing solution according to one embodiment of the present invention, high-melting-point metals such as ruthenium contained in the semiconductor substrate can be selectively removed from the copper, and galvanic corrosion on the surface of the copper can be suppressed.

[0102] 11 Substrate 12 Resist 13 Seed layer 14 Metal layer 15 Flow meter 16 100 mL PFA trap bottle 17 500 mL PFA trap bottle 18 Rotor 19 PFA tube 20 Ice water 21 Three-neck flask 22 Thermometer protection tube 23 Thermometer 24 Rotor 25 PFA tube 26 Gas washing bottle 27 5% by mass sodium hydroxide aqueous solution 28 Flow meter 29 Water bath

Claims

1. A semiconductor processing solution comprising a carboxylic acid and a hypohalite ion, wherein the concentration of the carboxylic acid is 0.0001 mol / L or more and 1.0 mol / L or less, the hypohalite ion is at least one selected from the group consisting of hypochlorite ions and hypobromite ions, the concentration of the hypohalite ion is 0.0001 mol / L or more and 3.0 mol / L or less, and the pH at 25°C is 7.0 or more and 14.0 or less.

2. The semiconductor processing solution according to claim 1, wherein the carboxylic acid is a compound represented by formula (1). R-COOH ... (1) (In formula (1), R is a hydrogen atom, a C1-C10 alkyl group having one or more substituents X, or a phenyl group having one or more substituents X, wherein the substituent X is at least one selected from the group consisting of a hydroxyl group, a carbonyl group, and an alkoxy group, and if R has multiple substituents X, each substituent X may be the same or may be different.) 3. The semiconductor processing solution according to claim 2, wherein at least one of the substituents X is a carboxyl group.

4. The semiconductor processing solution according to claim 1, wherein the carboxylic acid is a carboxylic acid having one or more alkoxy groups.

5. The semiconductor processing solution according to claim 1, further comprising one or more metals selected from the group consisting of alkali metals and alkaline earth metals, and hydroxide ions.

6. The semiconductor processing solution according to claim 5, wherein the total concentration of one or more metals selected from the group consisting of alkali metals and alkaline earth metals is 1 ppm by mass or more and 10.0% by mass or less.

7. A method for processing a semiconductor substrate having copper and a high-melting-point metal, comprising removing the high-melting-point metal using a semiconductor processing solution according to any one of claims 1 to 6.

8. The processing method according to claim 7, wherein the high melting point metal is one or more metals selected from the group consisting of titanium, tantalum, ruthenium, molybdenum, tungsten, chromium, iridium, rhodium, platinum, and niobium.

9. A method for manufacturing a semiconductor substrate, comprising the method according to claim 7.

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