Semiconductor processing solution for removing ruthenium silicide

Abstract

To provide a semiconductor processing solution capable of removing ruthenium silicide while suppressing damage to a silicon substrate.SOLUTION: A semiconductor processing solution for removing ruthenium silicide from a substrate containing ruthenium silicide includes (i) at least one selected from the group consisting of hypochlorous acid, hypobromous acid, periodic acid, and ions thereof; (ii) at least one selected from the group consisting of hydrogen fluoride and fluoride ions; and (iii) an onium ion.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a semiconductor processing liquid for removing ruthenium silicide.

Background Art

[0002] In a semiconductor element, a wiring layer is formed for the purpose of extracting an electric signal emitted by a transistor to the outside. The semiconductor element has been miniaturized year by year, and when a material with low electromigration resistance or high resistance is used, it causes a decrease in the reliability of the semiconductor element and an inhibition of high-speed operation. Therefore, as a wiring material, a material with high electromigration resistance and low resistance value is desired. As such a material with high electromigration resistance and low resistance value, for example, aluminum and copper have been used so far, and recently, tungsten, cobalt, molybdenum, ruthenium, etc. have been studied. Among them, ruthenium has attracted particular attention as a wiring material with a semiconductor device design rule of 10 nm or less because of its high electromigration resistance and the ability to reduce the resistance value of the wiring. In addition, even when copper is used as a wiring material, the use of ruthenium as a barrier metal for copper wiring has also been studied.

[0003] When forming a wiring layer on a semiconductor element, a process of processing a wiring material is included, and dry or wet etching is used in this process. Among them, wet etching, which has high throughput and lower equipment cost compared to dry etching, is being studied for application to the next-generation wiring formation process. Furthermore, in recent years, ruthenium silicide has attracted attention as a wiring material and a barrier metal. Ruthenium silicide is particularly expected as a barrier metal and has the characteristic of suppressing the movement of oxygen from the silicon oxide film to the metal wiring. Ruthenium silicide is an Ru-Si alloy and is known to have structures such as RuSi, RuSi2, Ru2Si3, Ru2Si, and Ru4Si3. In particular, RuSi2 has a semiconductor phase with a stable FeSi-type structure and a metal phase with a high-temperature CsCl-type structure, and is also expected to be used as a thermoelectric conversion material. A thermoelectric conversion material is a material that generates electricity due to a temperature difference and has the characteristic of being able to convert heat into electricity.

[0004] However, with ruthenium and conventional metal etching solutions, the etching rate of ruthenium silicide is not sufficient, and it has been difficult to effectively remove ruthenium silicide. Therefore, there has been a demand for an etching solution that can effectively remove ruthenium silicide. In Patent Document 1, a solution containing calcium hypochlorite and hydrofluoric acid has been proposed as an etching solution for ruthenium silicide. It is described that the solution can remove a 1000 Å ruthenium silicide film in a 3-minute treatment. As the etching mechanism, the hydrofluoric acid in the solution removes the surface silicon oxide film, exposing ruthenium atoms and silicon atoms. Next, the oxidizing agent in the solution oxidizes and dissolves ruthenium and oxidizes silicon to form silicon oxide. Subsequently, it is presumed that the silicon oxide in the solution is removed by hydrofluoric acid, and the etching proceeds in such a cycle.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, when the etching solution described in Patent Document 1 was used, it was confirmed that the silicon substrate on the back surface was also etched, and the silicon substrate was damaged so much that it could be visually confirmed. When observing the damaged part with a scanning electron microscope, hillocks indicating that silicon was anisotropically etched were confirmed. As a presumed mechanism, it is considered that a silicon oxide film is formed on the silicon substrate by an oxidizing agent in the solution, and the formed silicon oxide film is etched by hydrofluoric acid. From such circumstances, a semiconductor treatment liquid capable of removing ruthenium silicide without damaging the silicon substrate has been desired.

[0007] Therefore, an object of the present invention is to provide a semiconductor treatment liquid that can remove ruthenium silicide while suppressing damage to a silicon substrate.

Means for Solving the Problems

[0008] The inventors of the present invention have intensively studied to solve the above problems. As a result, (i) At least one selected from the group consisting of hypochlorous acid, hypobromous acid, and periodic acid, and ions thereof, (ii) At least one selected from the group consisting of hydrogen fluoride and fluoride ions, and (iii) Onium ion It has been found that a semiconductor treatment liquid for removing ruthenium silicide containing the above can remove ruthenium silicide while suppressing damage to a silicon substrate, and the present invention has been completed. That is, the configuration of the present invention is as follows.

[0009] <1> A semiconductor treatment liquid used to remove ruthenium silicide from a substrate containing ruthenium silicide, (i) At least one selected from the group consisting of hypochlorous acid, hypobromous acid, and periodic acid, and ions thereof, (ii) At least one selected from the group consisting of hydrogen fluoride and fluoride ions, and (iii) Onium ion A semiconductor processing liquid for removing ruthenium silicide, containing . <2>The semiconductor processing liquid for removing ruthenium silicide according to <1>, wherein the (i) is at least one selected from the group consisting of hypochlorous acid and hypochlorite ions. <3>The semiconductor processing liquid for removing ruthenium silicide according to <1> or <2>, wherein the total concentration of the (i) in the semiconductor processing liquid is 0.001 mol / L to 0.50 mol / L based on the amount of halogen element. <4>The semiconductor processing liquid for removing ruthenium silicide according to any one of <1> to <3>, wherein the total concentration of the (ii) in the semiconductor processing liquid is 0.001 mol / L to 10.0 mol / L based on the amount of fluorine element. <5>The semiconductor processing liquid for removing ruthenium silicide according to any one of <1> to <4>, wherein the total concentration of the (iii) in the semiconductor processing liquid is 0.001 mol / L to 10.0 mol / L. <6>The semiconductor processing liquid for removing ruthenium silicide according to any one of <1> to <5>, wherein the pH of the semiconductor processing liquid at 25 °C is 0.0 to 10.0. <7>The semiconductor processing liquid for removing ruthenium silicide according to any one of <1> to <6>, wherein the (iii) is an onium ion represented by the following formula (1). [Chemical formula] In formula (1), R 1 , R 2 , R 3 , R 4 are each independently an alkyl group having 1 to 9 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 9 carbon atoms, or an aryl group. At least one hydrogen in the aryl group in the aralkyl group and the ring of the aryl group may be replaced by fluorine, chlorine, an alkyl group having 1 to 9 carbon atoms, an alkenyl group having 2 to 9 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, or an alkenyloxy group having 2 to 9 carbon atoms. In these groups, at least one hydrogen may be replaced by fluorine, chlorine, bromine, or iodine. A method for manufacturing a semiconductor device, comprising a step of etching ruthenium silicide by bringing a substrate containing ruthenium silicide into contact with the semiconductor processing liquid according to any one of <1> to <7>.

Effect of the Invention

[0010] According to the present invention, it is possible to provide a semiconductor processing liquid for removing ruthenium silicide while suppressing damage to a silicon substrate.

Brief Description of the Drawings

[0011]

Figure 1

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these contents as long as it does not exceed the gist thereof. Further, the present invention can be arbitrarily modified and implemented within a range not departing from the gist thereof. In this specification, a numerical range represented by "~" means a range including the numerical values described before and after "~" as a lower limit value and an upper limit value, and "A~B" means A or more and B or less. Further, when the numerical ranges are described stepwise, the upper limit and the lower limit of each numerical range can be arbitrarily combined. Also, in this specification, the expression "A or B" can be read as "at least one selected from the group consisting of A and B".

[0013] (Semiconductor Processing Liquid) The semiconductor processing liquid of the present embodiment (hereinafter also referred to as the processing liquid) is a semiconductor processing liquid used to remove ruthenium silicide from a substrate containing ruthenium silicide, (i) At least one selected from the group consisting of hypochlorous acid, hypobromous acid, and periodic acid, and ions thereof, (ii) At least one selected from the group consisting of hydrogen fluoride and fluoride ions, and (iii) an onium ion A semiconductor processing liquid for removing ruthenium silicide, which contains these.

[0014] (Oxidizing agent) The semiconductor processing liquid of this embodiment (i) contains at least one selected from the group consisting of hypochlorous acid, hypobromous acid, periodic acid, and ions thereof. These halogen oxyacids and ions act as oxidizing agents for removing ruthenium silicide. These oxidizing agents have the function of oxidizing and dissolving ruthenium atoms in ruthenium silicide and the function of oxidizing silicon atoms in ruthenium silicide to silicon oxides. Hereinafter in this specification, the above halogen oxyacids and ions are also collectively referred to simply as oxidizing agents. The total concentration of the oxidizing agent contained in the semiconductor processing liquid of this embodiment is not particularly limited, but from the viewpoint of sufficiently oxidizing and dissolving ruthenium silicide, it is preferably 0.001 mol / L or more and 0.50 mol / L or less as the amount of halogen element with respect to the total amount of the processing liquid, more preferably 0.005 mol / L or more and 0.20 mol / L or less, and particularly preferably 0.01 mol / L or more and 0.10 mol / L or less. When hypobromous acid, hypobromite ion, hypochlorous acid, and / or hypochlorite ion is selected as the oxidizing agent contained in the semiconductor processing liquid of this embodiment, although not particularly limited, from the viewpoint of sufficiently oxidizing and dissolving ruthenium silicide, the total concentration of hypobromous acid, hypobromite ion, hypochlorous acid, and hypochlorite ion is preferably 0.001 mol / L or more and 0.50 mol / L or less as the amount of halogen element with respect to the total mass of the processing liquid, more preferably 0.005 mol / L or more and 0.20 mol / L or less, and particularly preferably 0.01 mol / L or more and 0.10 mol / L or less. When periodic acid and / or periodate ions are selected as the oxidizing agent contained in the semiconductor processing liquid of the present embodiment, although not particularly limited, from the viewpoint of sufficiently oxidizing and dissolving ruthenium silicide, the total concentration of periodic acid and periodate ions is preferably 0.001 mol / L or more and 0.50 mol / L or less, more preferably 0.005 mol / L or more and 0.20 mol / L or less, and particularly preferably 0.01 mol / L or more and 0.10 mol / L or less in terms of the amount of iodine element relative to the total amount of the processing liquid. In the present specification, periodic acid (or its ion) means including both orthoperiodic acid (or its ion) and metaperiodic acid (or its ion) unless otherwise specified. Also, since periodate ions ionize when dissolved in water, they may be added in the form of a salt. Orthoperiodic acid is more preferable than metaperiodic acid in terms of not containing metals such as Na and having a stable composition.

[0015] From the viewpoint of the removal efficiency of ruthenium silicide, it is preferably included at least one selected from the group consisting of hypochlorous acid and hypochlorite ions.

[0016] The halogen oxyacid and / or halogen oxyacid ion selected as the oxidizing agent contained in the semiconductor processing liquid of the present embodiment may be one kind or two or more kinds. By containing a plurality of kinds, it may be possible to stabilize the etching rate and improve the stability during reuse. For example, when the first kind of halogen oxyacid ion contains hypobromite ion, bromide ion is generated as oxidation consumption and disproportionation decomposition proceed. A decrease in the concentration of halogen oxyacid ions causes a decrease in the etching rate. However, if the processing liquid contains hypochlorite ion as the second kind of halogen oxyacid ion, the generated bromide ion can be oxidized and changed back to hypobromite ion. This makes it easier to obtain stabilization of the etching rate. For the above reasons, when the semiconductor processing liquid of the present embodiment contains hypobromite ions, it is preferable that hypochlorite ions coexist. When hypobromite ions and hypochlorite ions coexist, the concentration of hypochlorite ions is not limited as long as it does not deviate from the gist of the present invention, but it is preferably 0.001 mol / L or more and 1.0 mol / L or less. When the concentration of hypochlorite ions is 0.001 mol / L or more, Br - can be efficiently oxidized, and it becomes easier to maintain the removal efficiency (etching rate) of ruthenium silicide. On the other hand, when the content of hypochlorite ions is 1.0 mol / L or less, the stability of hypochlorite ions is easily maintained , and it is easy to suppress the decomposition of hypobromite ions due to the reaction between hypochlorite ions / hypobromite ions. The concentration of hypochlorite ions is more preferably 0.001 mol / L or more and 1.0 mol / L or less, and most preferably 0.01 mol / L or more and 0.5 mol / L or less. For the same reason, specific examples of the combination of oxidizing agents coexisting in the semiconductor processing liquid include combinations of hypochlorite ions and hypobromite ions, combinations of hypochlorous acid and hypobromous acid, combinations of hypochlorite ions and orthoperiodate ions, combinations of hypobromite ions and orthoperiodate ions, combinations of hypochlorous acid and orthoperiodic acid, combinations of hypobromous acid and orthoperiodic acid, combinations of hypochlorite ions and orthoperiodic acid, combinations of hypobromite ions and orthoperiodic acid, combinations of hypochlorous acid and orthoperiodate ions, and combinations of hypobromous acid and orthoperiodate ions are preferred. From the viewpoint of stability, combinations of hypochlorite ions and hypobromite ions, and combinations of hypochlorous acid and hypobromous acid are more preferred.

[0017] Note that the above halogen oxyacids and their ions are in the acid form (e.g., HBrO) and ionic form (e.g., BrO -) may coexist in the treatment liquid. When a halogen oxyacid and the corresponding ion coexist in the treatment liquid, the total concentration of the acid form and the ionic form may be treated as the above-preferred ionic concentration.

[0018] The method of incorporating the above oxidizing agent into the semiconductor treatment liquid is not particularly limited. It may be added in the form of an aqueous solution containing the above halogen oxyacid, or it may be generated by blowing a halogen gas into the treatment liquid, or a salt containing the above halogen oxyacid ion as an anion may be added to the treatment liquid. From the viewpoints of ease of preparing the treatment liquid and pH adjustment, it is preferably added in the form of a salt of an organic alkali and a halogen oxyacid, and more preferably added in the form of a salt of a tetraalkylammonium hydroxide and a halogen oxyacid.

[0019] (Decomposition product) The treatment liquid of this embodiment may contain at least one ion selected from the group consisting of bromide ion, bromite ion, bromate ion, chloride ion, chlorite ion, chlorate ion, iodide ion, triiodide ion, and iodate ion. These ions are decomposition products of the respective halogen oxyacid ions and are ions that can be generated over time in the liquid. In particular, during the production of hypochlorous acid and hypobromous acid, an equal amount of chloride ion or bromide ion is mixed with hypochlorite ion or hypobromite ion. The concentration of these ions is not particularly limited, but specifically, it is preferably contained in the semiconductor treatment liquid in the range of 0.0001 mol / L or more and 5.0 mol / L or less. Considering the stability of the halogen oxyacid ion, a range of 0.001 mol / L or more and 3.0 mol / L or less is more preferable.

[0020] (pH) The pH of the semiconductor processing liquid of this embodiment is preferably in the range of pH 0.0 to 10.0 where hydrogen fluoride can stably exist. More preferably, it is pH 0.0 to 5.5 where hydrogen fluoride can exist more stably. As the pH increases, the amount of hydrogen fluoride that can exist in the processing liquid decreases, so the etching rate tends to decrease. On the other hand, roughening of the surface of the substrate to be processed is likely to be suppressed. Also, within this range, there is a preferred pH range depending on the selected halogen oxyacid or its ion. For example, when at least one of hypobromous acid, hypochlorous acid, and their ions is selected as the halogen oxyacid or its ion, a pH of 2.0 or higher is preferable because it is easy to suppress the decomposition of these acids or ions. Therefore, when at least one of hypobromous acid, hypochlorous acid, and their ions is selected as the halogen oxyacid or its ion, the pH of the semiconductor processing liquid is preferably in the range of pH 2.0 to 10.0, and more preferably in the range of pH 2.0 to 5.5. When the semiconductor processing liquid of this embodiment contains periodate ions as the halogen oxyacid ions, from the viewpoints of solubility, smoothness, and stability of etching performance, the pH of the semiconductor processing liquid is preferably in the range of pH 0.0 to 8.0, and more preferably in the range of pH 0.0 to 5.5. In this specification, the pH is the value at 25°C.

[0021] (Hydrogen fluoride and / or fluoride ions) The semiconductor processing liquid according to this embodiment contains hydrogen fluoride and / or fluoride ions. That is, the semiconductor processing liquid contains both hydrogen fluoride and fluoride ions, or contains hydrogen fluoride or fluoride ions. Hydrogen fluoride or fluoride ions have the effect of increasing the removal efficiency (etching rate) of ruthenium silicide by dissolving silicon oxide, which is the surface oxide film of ruthenium silicide, and silicon oxide in ruthenium silicide oxidized by an oxidizing agent as hexafluorosilicate ions. The method of incorporating hydrogen fluoride or fluoride ions into the semiconductor processing liquid is not particularly limited. For example, it may be added in the form of an aqueous solution of hydrogen fluoride (hydrofluoric acid), or a salt containing fluoride ions as an anion may be added to the processing liquid, or an aqueous solution obtained by neutralizing an alkali compound with hydrofluoric acid may be added. From the viewpoint of easy preparation of the processing liquid, it is preferably added in the form of an onium salt fluoride (onium fluoride salt) described later. When fluoride ions are added in the form of a salt, part or all of the fluoride ions will become hydrogen fluoride (HF) or bifluoride ions (HF2 - ) due to chemical equilibrium. And the simultaneous presence of HF or HF2 - and the above oxidizing agent in the semiconductor processing liquid enables the etching of ruthenium silicide.

[0022] The total concentration of hydrogen fluoride and fluoride ions contained in the semiconductor processing liquid is not particularly limited, but from the viewpoint of enhancing the removal efficiency of ruthenium silicide, it is preferably 0.001 mol / L or more and 10.0 mol / L or less in terms of the amount of fluorine element, more preferably 0.005 mol / L or more and 5.0 mol / L or less, and particularly preferably 0.01 mol / L or more and 2.0 mol / L or less.

[0023] (onium ion) The semiconductor processing liquid of this embodiment contains onium ions. As a method of adding onium ions to the semiconductor processing liquid, any onium salt may be directly added, or an aqueous solution obtained by neutralizing an organic alkali containing onium ions with an acid may be added as a salt. From the viewpoint of easy preparation of the processing liquid, it is preferably added to the semiconductor processing liquid in the form of a salt with the above-mentioned fluoride ions, that is, an onium fluoride salt. The inclusion of onium ions in the semiconductor processing liquid can suppress damage to the silicon substrate. This is presumably because the onium ions adsorb on the surface of the silicon substrate due to hydrophobic interaction, inhibiting etching by hydrogen fluoride and making it possible to suppress damage.

[0024] Examples of onium ions or onium salts serving as sources of onium ions include tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, chlorocholine ion, trans-2-butene 1,4-bis(triphenylphosphonium ion), 1-hexyl-3-methylimidazolium ion, allyltriphenylphosphonium ion, tetraphenylphosphonium ion, benzyltriphenylphosphonium ion, methyltriphenylphosphonium ion, (2-carboxyethyl )triphenylphosphonium ion, (3-carboxypropyl)triphenylphosphonium ion, (4-carboxybutyl)triphenylphosphonium ion, (5-carboxypentyl)triphenylphosphonium ion, cinnamyltriphenylphosphonium ion, (2-hydroxybenzyl)triphenylphosphonium ion, (1-naphthylmethyl)triphenylphosphonium ion, butyltriphenylphosphonium ion, (tert-butoxycarbonylmethyl)triphenylphosphonium ion, allyltriphenylphosphonium ion, (3-methoxybenzyl)triphenylphosphonium ion, (methoxymethyl)triphenylphosphonium ion, (1-ethoxy-1-oxopropan-2-yl)triphenylphosphonium ion, (3,4-dimethoxybenzyl)triphenylphosphonium ion, methoxycarbonylmethyl(triphenyl)phosphonium ion, (2,4-dichlorobenzyl)triphenylphosphonium ion, (2-hydroxy-5-methylphenyl)triphenylphosphonium ion, (4-chlorobenzyl)triphenylphosphonium ion, (3-chloro-2-hydroxypropyl)trimethylammonium ion, methacryloylcholine ion, benzoylcholine ion, benzyldimethylphenylammonium ion, (2-methoxyethoxymethyl)triethylammonium ion, carbamylcholine ion, 1,1'-difluoro-2,2'-bip Rhodinium bis(tetrafluoroborate), benzyltributylammonium ion, trimethylphenylammonium ion, 5-azoniaspiro[4.4]nonane ion, tributylmethylammonium ion, tetrabutylammonium ion, tetraamylammonium ion, tetrabutylphosphonium ion, diallyldimethylammonium ion, 1,1-dimethylpiperidinium ion, (2-hydroxyethyl)dimethyl(3-sulfopropyl)ammonium hydroxide, 3-(trifluoromethyl)phenyltrimethylammonium ion, 1,1'-(decane-1,10-diyl)bis[4- aza-1-azonabicyclo[2.2.2]octane] diion, (3-bromopropyl)trimethylammonium ion, vinylbenzyltrimethylammonium ion, allyltrimethylammonium ion, trimethylvinylammonium ion, choline ion, β-methylcholine ion, and triphenylsulfonium ion and salts thereof at least one selected from the group consisting of

[0025] As the onium ion, it is preferable to select one or more selected from the group consisting of onium ions represented by the following formulas (1) to (6).

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0026] In Formulas (1) to (6), R 1 、R 2 、R 3 、R 4 、R 5 、R 6 are each independently an alkyl group having 1 to 9 carbon atoms (preferably 1 to 3 carbon atoms), an allyl group, an aralkyl group having an alkyl group having 1 to 9 carbon atoms (preferably 1 to 3 carbon atoms), or an aryl group. Further, at least one hydrogen in the aryl group in the aralkyl group and the ring of the aryl group may be replaced by fluorine, chlorine, an alkyl group having 1 to 9 carbon atoms (preferably 1 to 3 carbon atoms), an alkenyl group having 2 to 9 carbon atoms (preferably 2 to 3 carbon atoms), an alkoxy group having 1 to 9 carbon atoms (preferably 1 to 3 carbon atoms), or an alkenyloxy group having 2 to 9 carbon atoms (preferably 2 to 3 carbon atoms), and at least one hydrogen in these groups may be replaced by fluorine, chlorine, bromine, or iodine. A is an ammonium ion, a phosphonium ion, or an arsonium ion. Z is an aromatic group or an alicyclic group which may contain a nitrogen, sulfur, or oxygen atom, and in the aromatic group or the alicyclic group, carbon or nitrogen may be substituted by chlorine, bromine, fluorine, iodine, at least one alkyl group having 1 to 9 carbon atoms, at least one alkenyloxy group having 2 to 9 carbon atoms, an aromatic group which may be substituted by at least one alkyl group having 1 to 9 carbon atoms, or an alicyclic group which may be substituted by at least one alkyl group having 1 to 9 carbon atoms. R is chlorine, bromine, fluorine, iodine, an alkyl group having 1 to 9 carbon atoms, an allyl group, an aromatic group which may be substituted by at least one alkyl group having 1 to 9 carbon atoms, or an alicyclic group which may be substituted by at least one alkyl group having 1 to 9 carbon atoms. n is an integer of 1 or 2 and indicates the number of Rs. When n is 2, the Rs may be the same or different and may form a ring or may form a ring. a is an integer of 1 to 10 (preferably 6 to 10).

[0027] As the onium ions represented by formulas (1) to (6), specifically, at least one selected from the group consisting of ammonium ions, tetraalkylammonium cations, tetraalkylphosphonium cations, tetraalkylarsonium cations, trialkylsulfonium cations, hydrazinium dication, diazenium dication, and diazonium dication can be mentioned. Since it is difficult to be decomposed by halogen oxyacid ions, at least one selected from the group consisting of tetraalkylammonium cations, tetraalkylphosphonium cations, tetraalkylarsonium cations, trialkylsulfonium cations, and hydrazinium dication is preferable. Since it has a property of being easily adsorbed to the silicon substrate by hydrophobic interaction, at least one selected from the group consisting of tetraalkylammonium cations, tetraalkylphosphonium cations, and tetraalkylarsonium cations is more preferable. Since it is difficult to be adsorbed to ruthenium silicide, tetraalkylammonium cations are even more preferable.

[0028] As the tetraalkylammonium cation, specifically, at least one selected from the group consisting of tetramethylammonium cation, tetraethylammonium cation, tetrapropylammonium cation, tetrabutylammonium cation, and tetraamylammonium cation can be mentioned. From the adsorption to the silicon substrate and the etching rate of ruthenium silicide, at least one selected from the group consisting of tetramethylammonium cation, tetraethylammonium cation, and tetrapropylammonium cation is preferable. Since it is hardly oxidized by halogen oxyacid, at least one selected from the group consisting of tetramethylammonium cation and tetraethylammonium cation is more preferable. The longer the chain length of the alkyl group of the tetraalkylammonium cation, the more the roughness of the substrate can be suppressed, while the etching rate of ruthenium silicide tends to decrease.

[0029] The total concentration of onium ions contained in the semiconductor processing liquid is not particularly limited, but from the balance between the removal efficiency of ruthenium silicide and the suppression of damage to the silicon substrate, it is preferably 0.001 mol / L or more and 10.0 mol / L or less, more preferably 0.005 mol / L or more and 5.0 mol / L or less, and particularly preferably 0.01 mol / L or more and 2.0 mol / L or less.

[0030] When hydrogen fluoride and / or fluoride ions and onium ions are added to the semiconductor processing liquid in the form of an onium fluoride salt, the content of the onium fluoride salt is preferably in the range of 0.001 mol / L or more and 10.0 mol / L or less from the viewpoint of the etching rate of ruthenium silicide, preferably 0.01 mol / L or more and 5.0 mol / L or less from the viewpoints of the etching rate of ruthenium silicide and the damage to the silicon substrate, and more preferably 0.05 mol / L or more and 2.0 mol / L or less because ruthenium silicide can be etched more efficiently without damaging the silicon substrate.

[0031] In addition, the concentration of each ion in the semiconductor processing liquid can be confirmed using a known method. For example, when using ultraviolet-visible absorption photometry, absorption due to hypohalous acid ions can be easily confirmed, and the concentration of each ion can be determined from the intensity of its absorption peak (which depends on the pH of the processing liquid, the concentration of each ion, etc., for example, around 330 nm for hypobromous acid ions). Also, the concentration of each ion can be determined from titration methods, redox potentials, chromatographs, etc.

[0032] (Others) In the semiconductor processing liquid of the present embodiment, as other components, within a range that does not impair the object of the present invention known additives and the like used in semiconductor processing liquids may be blended. For example, as additives, acids other than those mentioned as the above oxidizing agents, metal corrosion inhibitors, water-soluble organic solvents, fluorine compounds other than the above hydrogen fluoride, reducing agents, complexing agents, chelating agents, surfactants, defoaming agents, pH adjusters, stabilizers, etc. can be added. These additives may be added alone or in combination of a plurality.

[0033] As a pH adjuster, an acid or an alkali may be added to the semiconductor processing liquid of the present embodiment. As the acid, it is preferable to use an acid that does not contain metal ions that pose a problem in semiconductor manufacturing, and at least one selected from the group consisting of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, boric acid, acetic acid, toluenesulfonic acid, and methanesulfonic acid can be mentioned. As the alkali, since it does not contain metal ions that pose a problem in semiconductor manufacturing, it is preferable to use an organic alkali. Among them, since the number of hydroxide ions per unit weight is large, high-purity products are easily available, and it is also useful as a source of onium ions, the organic alkali is preferably tetraalkylammonium hydroxide, and more preferably tetramethylammonium hydroxide.

[0034] The semiconductor processing liquid of the present embodiment preferably uses water as a solvent. The water as the solvent is preferably water from which metal ions, organic impurities, particulate particles, etc. have been removed by distillation, ion exchange treatment, filter treatment, various adsorption treatments, etc., and particularly pure water and ultrapure water are preferred. Such water can be obtained by known methods widely used in semiconductor manufacturing.

[0035] The semiconductor processing liquid of the present embodiment is preferably stored at low temperature and / or shielded from light. By storing at low temperature and / or shielding from light, an effect of suppressing the decomposition of the oxidizing agent in the semiconductor processing liquid can be expected. Furthermore, by storing the semiconductor processing liquid in a container filled with an inert gas to prevent the mixing of carbon dioxide, the stability of the semiconductor processing liquid can be maintained. Also, the inner surface of the container, that is, the surface in contact with the semiconductor processing liquid, is preferably formed of an organic polymer material. This is because if the inner surface of the container is formed of an organic polymer material, it is not affected by hydrogen fluoride, and the mixing of impurities such as metals, metal oxides, and organic substances can be further reduced. Examples of suitable organic polymer materials include PFA (perfluoroalkoxy fluororesin), PE (polyethylene), and PP (polypropylene).

[0036] <Method for manufacturing semiconductor processing liquid (etching liquid)> The method for obtaining the semiconductor processing liquid of the present embodiment is not particularly limited, and known methods for manufacturing semiconductor processing liquids may be appropriately applied. For example, solutions containing the necessary components may be mixed respectively. As a mixing method for each solution, for example, a method using a mixing tank, a method of mixing in the piping of a semiconductor manufacturing apparatus (in-line mixing), a method of mixing by simultaneously applying a plurality of liquids onto a substrate, etc. can be preferably used. More specifically, for example, it can be obtained by the following method. First, prepare a solution (for example, an aqueous solution of alkyl onium hydroxide) that serves as a source of onium ions in a sealable container. Next, supply a halogen gas or liquid halogen to the container to obtain a mixed solution of an aqueous solution of hypohalous acid onium and alkyl onium hydroxide. At this time, a step of expelling carbon dioxide in the gas phase by flowing an inert gas into the container may be included. Also, the source of onium ions may be prepared in the form of a salt (for example, onium fluoride salt). By mixing other necessary components (for example, hydrofluoric acid, solvent, pH adjuster, etc.) in a desired amount with the prepared mixed solution of an aqueous solution of hypohalous acid onium and alkyl onium hydroxide, the semiconductor processing liquid according to the present embodiment can be obtained.

[0037] (Etching method for ruthenium silicide) The semiconductor processing liquid of the present embodiment can be used for etching ruthenium silicide on a substrate. The etching method includes a step of bringing the substrate into contact with the semiconductor processing liquid of the present embodiment. The substrate is not particularly limited as long as ruthenium silicide exists on the surface, but for example, it is a semiconductor wafer. In this specification, the case where the semiconductor processing liquid of the present embodiment is used as an etching liquid for etching ruthenium silicide is mainly described as an example, but it is not limited to this as long as the purpose is to remove ruthenium silicide. For example, it can be used as a cleaning liquid, an etching liquid for residues after dry etching, an etching liquid for bevel / back surface, and an etching liquid for recess etching. The semiconductor processing liquid of this embodiment can be preferably used as an etching liquid for semiconductor wafers. The etching method performed using the processing liquid of this embodiment will be described by using the etching of a ruthenium silicide film laminated on a silicon substrate. First, a substrate made of a semiconductor (for example, Si) is prepared. The prepared substrate is subjected to a hydrofluoric acid treatment to remove the natural oxide film of silicon formed on the substrate. Then, using ruthenium and silicon as targets, with the ratio of ruthenium to silicon to be sputtered being 1:2, they are simultaneously laminated on the silicon substrate by PVD method. By bringing the ruthenium silicide (hereinafter also referred to as RuSi2) thus obtained into contact with the semiconductor processing liquid according to this embodiment, an etching treatment is performed to completely remove the ruthenium silicide. The semiconductor wafer to be etched may contain metals other than ruthenium silicide. Specifically, it may contain at least one transition metal selected from the group consisting of Ru, Rh, Ti, Ta, Co, Cr, Hf, Os, Pt, Ni, Mn, Cu, Zr, La, Mo, and W. When metals other than ruthenium silicide are contained, they may be removed with known semiconductor processing liquids corresponding to each metal as necessary.

[0038] The temperature when etching ruthenium silicide using the semiconductor processing liquid of this embodiment is not particularly limited and may be determined in consideration of the etching rate of ruthenium silicide, etc. When the processing temperature is high, the stability of the halogen oxyacid decreases. On the other hand, the lower the temperature, the more the etching rate tends to decrease. For these reasons, the temperature for etching ruthenium silicide is preferably 10°C to 90°C, more preferably 15°C to 60°C, and most preferably 25°C to 45°C.

[0039] (Method for manufacturing a semiconductor device) By including the step of bringing the semiconductor processing liquid of this embodiment into contact with a semiconductor wafer containing ruthenium silicide and performing etching, a semiconductor device can be manufactured. An example of the manufacturing process of a semiconductor device will be described with reference to FIG. 1. When a filtration process is included during the manufacturing of a semiconductor device, the semiconductor processing liquid may have the opportunity to pass through filters 1 and 2 or 3. When the second valve 10 in FIG. 1 is closed and the first valve 9 is opened, the chemical solution in the chemical cabinet 6 is filtered by passing through filters 1 and 2 by driving the first pump 4. In order to remove impurities in the chemical solution in the chemical cabinet 6 as much as possible, the filtration process in which the chemical solution passes through filters 1 and 2 may be performed multiple times. The number of filters to be passed through during one filtration process can be, for example, 1 or more, 2, 3, or 4 or more. When the second valve 10 in FIG. 1 is opened, the chemical solution in the chemical cabinet 6 is supplied to the etching table 8 by driving the first pump 4, and the semiconductor wafer is etched. Also, in order to replenish the chemical solution in the chemical cabinet 6, the chemical solution in the chemical replenishment unit 7 passes through the filter 3 by driving the second pump 5 and is replenished into the chemical cabinet 6. Note that the chemical solution described here may be the semiconductor processing liquid itself or a chemical solution obtained by adding a decomposition inhibitor to the semiconductor processing liquid. Note that the manufacturing method of a semiconductor device may include one or more processes selected from a wafer manufacturing process, an oxide film forming process, a transistor forming process, a wiring forming process, and a CMP process, etc., which are known processes used in the manufacturing method of a semiconductor device. Also, in the manufacturing method of a semiconductor device, a used semiconductor processing liquid can be used. Specifically, the manufacturing method of a semiconductor device may include a process of recovering the semiconductor processing liquid after the etching process of a semiconductor wafer and a process of etching the semiconductor wafer using the recovered processing liquid. The manufacturing method of a semiconductor device may include a process of measuring the concentration of an oxidizing agent in the recovered processing liquid.

Example

[0040] Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to these examples.

[0041] <Raw materials used> The oxidizing agents used in the semiconductor processing solutions of the Examples and Comparative Examples were prepared by the following method. (Production of tetramethylammonium hypochlorite solution) 209 g of 25% by mass tetramethylammonium hydroxide aqueous solution (Tokuyama) and 791 g of ultrapure water were mixed in a 2 L glass three-neck flask (Cosmos Bead Co., Ltd.) to obtain a 5.2% by mass tetramethylammonium hydroxide aqueous solution with a CO2 content of 0.5 ppm. The pH of this 5.2% by mass tetramethylammonium hydroxide aqueous solution at 25°C was 13.8.

[0042] Next, a rotor (AsOne, total length 30 mm × 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. A PFA tube (F-80, Fluoro Industries, Ltd.) connected to a chlorine gas cylinder and a nitrogen gas cylinder was placed in another opening, allowing the chlorine gas / nitrogen gas to be switched between the two at will. 11-02) was added and the tip of the PFA tube was immersed in the bottom of the solution. The remaining opening was connected to a gas washing bottle (AsOne, gas washing bottle, model number 2450 / 500) filled with a 5% by mass aqueous solution of sodium hydroxide. Next, nitrogen gas with a carbon dioxide concentration of less than 1 ppm was introduced from the PFA tube at a pressure of 0.289 Pa m 3 / sec (at 0°C) for 20 minutes to expel carbon dioxide from the gas phase, and the carbon dioxide concentration in the gas phase was reduced to 1 ppm or less.

[0043] After that, a magnetic stirrer (AsOne, C-MAG HS10) was placed at the bottom of the three-neck flask and rotated at 300 rpm to stir the mixture. While cooling the outer periphery of the three-neck flask with ice water, chlorine gas (Fujiox, specification purity 99.4%) was injected into the flask at a concentration of 0.059 Pa m 3It was supplied at 180 minutes at / second (when converted to 0 °C), and an aqueous solution 1 of tetramethylammonium hypochlorite (hypochlorite ion; corresponding to 3.51% by mass, 0.28 mol / L) and tetramethylammonium hydroxide (corresponding to 0.09% by mass, 0.0097 mol / L) was obtained. At this time, the liquid temperature during the reaction was 11 °C.

[0044] (Halogen oxyacid ion in the treatment liquid) When hypochlorous acid and / or hypochlorite ion was selected as the oxidizing agent, the mixed solution 1 obtained by the above operation was used at a predetermined concentration as the oxidizing agent (TMAClO in the table). When hypobromous acid and / or hypobromite ion was selected as the oxidizing agent, a predetermined amount of tetramethylammonium bromide (97% by mass, manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the mixed solution 1 obtained by the above operation, and it was used at a predetermined concentration as the oxidizing agent (TMABrO in the table). When periodate ion was selected as the oxidizing agent, a commercially available orthoperiodate (manufactured by Fujifilm Wako Pure Chemical Corporation) was used at a predetermined concentration as the oxidizing agent.

[0045] The other raw materials used in the semiconductor treatment liquids of each example and comparative example were the following raw materials. TMAH: 25 wt% tetramethylammonium hydride (SD-25, manufactured by Tokuyama) TEAH: 35 wt% tetraethylammonium hydride (manufactured by Tokyo Chemical Industry Co., Ltd.) TPAH: 40 wt% tetra-pentylammonium hydride (manufactured by Tokyo Chemical Industry Co., Ltd.) TBAH: 40 wt% tetrabutylammonium hydride (manufactured by Tokyo Chemical Industry Co., Ltd.) TMAF: 15 wt% aqueous solution of tetramethylammonium fluoride (manufactured by Tokyo Chemical Industry Co., Ltd.) TEAF: 15 wt% aqueous solution of tetraethylammonium fluoride (manufactured by Tokyo Chemical Industry Co., Ltd.) TBAF: 15 wt% aqueous solution of tetrabutylammonium fluoride (manufactured by Tokyo Chemical Industry Co., Ltd.) HF: 49 wt% hydrofluoric acid (manufactured by Fujifilm Wako Pure Chemical Corporation) Ca(ClO)2: Calcium hypochlorite (manufactured by Fujifilm Wako Pure Chemical Corporation) Hydrogen peroxide: 30 wt% hydrogen peroxide solution (manufactured by Fujifilm Wako Pure Chemical Corporation)

[0046] (Method for calculating the total concentration of hypochlorous acid, hypobromous acid, and their ions) The total concentration of hypochlorous acid, hypobromous acid, and their ions was measured using an ultraviolet-visible spectrophotometer (V-750, manufactured by JASCO Corporation). A calibration curve was prepared using aqueous solutions of hypobromite ions and hypochlorite ions with known concentrations, and the concentrations of hypobromite ions and hypochlorite ions in the manufactured semiconductor treatment solution were determined. Also, the concentrations of these acids were similarly calculated from the calibration curves of aqueous solutions of hypobromous acid and hypochlorous acid with known concentrations. The concentrations of these acids and ions were determined from the measurement data when the absorption spectrum was stable after mixing the respective raw materials.

[0047] (Method for calculating the concentration of periodic acid and periodate ions) The concentrations of periodic acid and periodate ions were calculated from the charged amount of orthoperiodate used as a raw material.

[0048] (Method for calculating the concentration of onium ions) The concentration of onium ions was calculated using an ion chromatograph (integrion, manufactured by Thermo Fisher Scientific). After preparing the treatment solutions of the examples and comparative examples, 1 g of the treatment solution was added to a 100 mL volumetric flask, and ultrapure water was poured up to the calibration line to obtain a measurement solution of each treatment solution diluted 100-fold. Next, calibration curves for each onium ion were prepared in the same procedure using each onium ion. The prepared measurement solution was measured in the cation measurement mode of the ion chromatograph. The onium ion concentration was calculated from the obtained peak area value based on the peak area value of the calibration curve prepared.

[0049] (Method for calculating the concentration of hydrogen fluoride and fluoride ions) The hydrogen fluoride concentration was calculated from the charged amount. The fluoride ion concentration was measured using an ion chromatograph (Integrion, manufactured by Thermo Fisher Scientific). After preparing the treatment liquids of the examples and comparative examples, 1 g of the treatment liquid was added to a 100 mL volumetric flask, and ultrapure water was poured in up to the calibration line to obtain a measurement liquid of each treatment liquid diluted 100-fold. Next, a calibration curve of fluoride ions was created in the same procedure using a 1000 ppm fluoride ion standard solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). The prepared measurement liquid was measured in the anion measurement mode of the ion chromatograph. Since the peak of fluoride ions is close to the water dip, a gradient was applied to obtain the peak of fluoride ions. The fluoride ion concentration was calculated from the area value of the obtained peak based on the area value of the peak of the calibration curve prepared in advance.

[0050] (pH) 10 mL of the treatment liquids prepared in the examples and comparative examples was measured for pH using a desktop pH meter (LAQUA F-73, manufactured by Horiba, Ltd.). The pH measurement was carried out after preparing the treatment liquid and allowing it to stabilize at 25°C.

[0051] (Preparation of treatment liquid) <Examples 1 to 20, Comparative Examples 1 to 6> The above raw materials were mixed in the compositions shown in Table 1, and ultrapure water was added so that the total amount became 100 parts by mass to prepare semiconductor treatment liquids according to Examples 1 to 20 and Comparative Examples 1 to 6.

[0052] (Evaluation of etching rate (ER)) 40 mL of the prepared treatment liquid was measured and placed in a 100 mL PFA container, and stirred at 1000 rpm using a magnetic stirrer (C-MAG HS10, manufactured by AsOne) installed at the bottom of the container. Thereafter, a ruthenium silicide (RuSi2) film with a thickness of 200 nm and a single crystal silicon film with a lattice plane of (100) and a thickness of 100 nm (hereinafter also referred to as Si(100) film) were respectively introduced into each treatment liquid, and an etching treatment was performed for 1 minute. The films after the etching treatment were thoroughly rinsed with ultrapure water and dried thoroughly with N2 blowing. The film thicknesses of ruthenium silicide before and after the etching treatment were evaluated by fluorescent X-ray analysis (ZSX Primus IV, manufactured by RIGAKU). The film thicknesses of Si(100) before and after the etching treatment were evaluated by spectroscopic ellipsometry (M-2000, manufactured by J. A. Woolam Japan).

[0053] (Evaluation of the surface state of the Si(100) film) Regarding the 100 nm Si(100) film used for the evaluation of the etching rate above, the surface states before and after etching were observed with a field emission scanning electron microscope (Regulus8230, manufactured by Hitachi), the presence or absence of surface roughness was confirmed, and the evaluation was performed according to the following criteria. A: No surface roughness is observed B: Slight 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] (Evaluation results) These evaluation results are shown in Table 2. In Comparative Example 1, the etching rate of ruthenium silicide was very high, but the surface state of the Si film after treatment was poor, and it was confirmed that it was whitened even visually. On the other hand, in Examples 1 to 20, ruthenium silicide could be etched while suppressing the deterioration of the surface state. Also, when Examples 1 to 5 are compared, it can be confirmed that the etching rate tends to decrease as the pH of the treatment liquid increases.

[0055] Comparative Examples 2 to 4 are representative compositions of a treatment liquid capable of etching ruthenium. With these treatment liquids, ruthenium can be etched, but it was impossible to etch ruthenium silicide. Similarly, as shown in Comparative Example 5, it was impossible to etch ruthenium silicide with only hydrofluoric acid.

[0056] When Examples 2, 6, and 7 are compared, it can be confirmed that the etching rate of ruthenium silicide tends to decrease as the amount of the oxidizing agent decreases. When Examples 2, 8 to 10 are compared, it can be confirmed that the etching rate of ruthenium silicide tends to increase as the amount of fluoride ions increases. When Examples 2, 11 to 18 are compared, a tendency for the change in the etching rate of ruthenium silicide due to the difference in onium ions can be confirmed. In Examples 2, 11 to 13, organic alkalis are all used as the onium ion supply source, but the alkyl group chain lengths of the quaternary ammonium cations are different. The longer the alkyl group chain length, the more possible it is to keep the surface state of Si(100) smooth, but at the same time, a tendency to suppress the etching rate of ruthenium silicide was confirmed. Examples 14 to 16 are examples using fluoride salts of tetraalkylammonium as the supply sources of onium ions and fluoride ions. Even with the fluoride salts of tetraalkylammonium, the results are similar to those when the organic alkali and hydrofluoric acid shown in Examples 8 to 13 are added respectively. Therefore, it can be seen that as the supply sources of onium ions and fluoride ions, a mixture of an organic alkali and hydrofluoric acid may be used, or an onium salt having fluoride ions as anions may be used.

[0057] Examples 2, 19, and 20 show the difference in the etching rate of ruthenium silicide due to the difference in the oxidizing agent. It was confirmed that ruthenium silicide can be suitably etched regardless of whether the oxidizing agent is hypochlorous acid, hypobromous acid, or periodic acid. As shown in Comparative Example 6, when hydrogen peroxide was used as the oxidizing agent, ruthenium silicide could not be etched. In addition, since hydrogen peroxide has a low oxidation-reduction potential (ORP), ruthenium in ruthenium silicide was oxidized to RuO2, contaminating the surface black.

[0058]

Table 1

Table 2

Explanation of Symbols

[0059] 1 Filter 1 2 Filter 2 3 Filter 3 4 First pump 5 Second pump 6 Chemical cabinet 7 Chemical replenishment unit 8 Etching table 9 First valve 10 Second valve

Claims

1. A semiconductor processing liquid used to remove ruthenium silicide from a substrate containing ruthenium silicide, comprising: (i) at least one selected from the group consisting of hypochlorous acid, hypobromous acid, periodic acid, and their ions; (ii) at least one selected from the group consisting of hydrogen fluoride and fluoride ions; and (iii) onium ions A semiconductor processing liquid for removing ruthenium silicide.

2. The semiconductor processing liquid for removing ruthenium silicide according to Claim 1, wherein the (i) is at least one selected from the group consisting of hypochlorous acid and hypochlorite ions.

3. The semiconductor processing liquid for removing ruthenium silicide according to Claim 1, wherein the total concentration of the (i) in the semiconductor processing liquid is 0.001 mol / L to 0.50 mol / L based on the amount of halogen element.

4. The semiconductor processing liquid for removing ruthenium silicide according to Claim 1, wherein the total concentration of the (ii) in the semiconductor processing liquid is 0.001 mol / L to 10.0 mol / L based on the amount of fluorine element.

5. The semiconductor processing liquid for removing ruthenium silicide according to Claim 1, wherein the total concentration of the (iii) in the semiconductor processing liquid is 0.001 mol / L to 10.0 mol / L.

6. The semiconductor processing liquid for removing ruthenium silicide according to Claim 1, wherein the pH of the semiconductor processing liquid at 25°C is 0.0 to 10.

0.

7. The semiconductor processing liquid for removing ruthenium silicide according to Claim 1, wherein the (iii) is an onium ion represented by the following formula (1). 【Chemical 1】 In formula (1), R １ , R ２ , R ３ , R ４ are each independently an alkyl group having 1 to 9 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 9 carbon atoms, or an aryl group, and at least one hydrogen in the aryl group and the ring of the aryl group in the aralkyl group may be replaced by fluorine, chlorine, an alkyl group having 1 to 9 carbon atoms, an alkenyl group having 2 to 9 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, or an alkenyloxy group having 2 to 9 carbon atoms, and in these groups, at least one hydrogen may be replaced by fluorine, chlorine, bromine, or iodine.

8. A method for manufacturing a semiconductor device, comprising the step of etching ruthenium silicide by bringing a substrate containing ruthenium silicide into contact with the semiconductor processing liquid according to any one of Claims 1 to 7.

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