Lubricant for filtration containing onium ions

Abstract

Provided is, for example, a lubricant for filtration which has a surface tension of 60-75 mN / m and which contains onium ions. Also provided are a composition for polishing which contains onium ions and hypohalous acid ions, a metal recovery agent which contains onium ions coordinated to metal oxide ions or metal hydroxide ions, and the like.

Description

Filtration lubricants containing onium ions

[0001] The present invention relates to a filtering lubricant and a polishing composition that suppress the reduction of onium salts during filtration in the manufacturing process of semiconductor devices.

[0002] In semiconductor devices, wiring layers are formed to transmit electrical signals generated by transistors to the outside. Semiconductor devices are becoming increasingly miniaturized, and using materials with low electromigration resistance or high resistance can lead to reduced reliability and impaired high-speed operation. Therefore, wiring materials with high electromigration resistance and low resistance are desired.

[0003] For example, aluminum and copper have been used so far as such materials, but recently, tungsten, cobalt, molybdenum, ruthenium, etc. are being considered. Forming a wiring layer on a semiconductor element involves a process of processing the wiring material, and this process uses dry or wet etching.

[0004] When wet etching wiring materials, the dissolution rate of the wiring material, i.e., the etching rate, is important. A fast etching rate allows the wiring material to be dissolved in a short time, which increases the number of wafers that can be processed per unit time.

[0005] Furthermore, problems specific to wiring materials may arise during etching. For example, when ruthenium is wet etched under alkaline conditions, the ruthenium becomes RuO ４ － and RuO ４ ２－ RuO ４ － and RuO ４ ２－ is RuO in the treatment solution. ４ A part of it is gasified and released into the gas phase. ４ is a strong oxidant and is therefore harmful to the human body, and is also easily reduced to RuO ２Generally, particles cause a serious problem in the semiconductor manufacturing process because they reduce the yield. ４ It is very important to suppress the generation of gas.

[0006] Patent Document 1 discloses a method for etching a RuO film that exhibits a good etching rate and stability of the rate. ４ A semiconductor wafer processing solution containing hypobromite ions has been proposed that can suppress gas generation.

[0007] International Publication No. 2021 / 059666

[0008] In semiconductor wafer wet etching equipment, a fine filter with a mesh size of several nanometers to several tens of nanometers is installed to remove particles from the processing solution. It has been found that when onium ions are added to a semiconductor processing solution and the solution is passed through a filter, the onium ion concentration in the solution decreases. This reduces the surface roughness during etching and the RuO ４ It was found that the gas suppression effect was greatly reduced.

[0009] Furthermore, in the wet etching process of semiconductor wafers, the processing solution used once for etching is usually recycled in order to reduce manufacturing costs. However, when the processing solution described in Patent Document 1 is used, it has been revealed that the etching rate decreases due to the recycling.

[0010] Therefore, an object of the present invention is to provide a filtration lubricant that does not reduce the onium ion concentration in the processing solution when filtered. Another object of the present invention is to provide a filtration lubricant that, when used as a semiconductor processing solution, can etch wiring materials, particularly ruthenium, contained in semiconductor wafers at a sufficient rate, and can reduce the RuO ４ To provide a filtration lubricant which not only reduces gas generation but also does not deteriorate in etching properties when reused.

[0011] The present inventors have conducted extensive research to solve the above problems and have found that the decrease in the concentration of onium ions can be suppressed by controlling the surface tension of the filtration lubricant. This allows the surface smoothness of the wiring material to be maintained and the RuO ４ Furthermore, the inventors have found that by appropriately controlling the type and concentration of the oxidizing agent and the type and concentration of the onium ion that may be contained in the filtration lubricant, in addition to controlling the surface tension, it is possible to suppress the deterioration of the etching characteristics when the treatment liquid containing the filtration lubricant is reused, and have completed the present invention.

[0012] That is, the present invention is configured as follows.

[0013] Item 1. A filtration lubricant containing an onium ion, the filtration lubricant having a surface tension at 25°C of 60 mN / m or more and 75 mN / m or less.

[0014] Item 2. The filtration lubricant according to Item 1, wherein the onium ion is at least one selected from the group consisting of onium ions represented by formulas (1) to (6): (In formulas (1) to (6), R １ , R ２ , R ３ , R ４ , R ５ , R ６are independently an alkyl group having 2 to 9 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 9 carbon atoms, or an aryl group. In addition, at least one hydrogen atom in the aryl group in the aralkyl group and in 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, and in these groups, at least one hydrogen atom may be replaced by fluorine, chlorine, bromine, or iodine. A is an ammonium ion or a phosphonium ion. Z is an aromatic group or alicyclic group which may contain nitrogen, sulfur, or oxygen atoms, and in the aromatic group or alicyclic group, carbon or nitrogen may have 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 with at least one alkyl group having 1 to 9 carbon atoms, or an alicyclic group which may be substituted with 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 with at least one alkyl group having 1 to 9 carbon atoms, or an alicyclic group which may be substituted with at least one alkyl group having 1 to 9 carbon atoms. n is an integer of 1 or 2 and indicates the number of R. When n is 2, R may be the same or different and may form a ring. a is an integer of 1 to 10.

[0015] Item 3. The filtration lubricant according to Item 1 or 2, wherein the concentration of the onium ions is 1 ppm by mass or more and 10,000 ppm by mass or less.

[0016] Item 4. The filtration lubricant according to any one of Items 1 to 3, further comprising 0.001 mol / L to 0.20 mol / L of hypohalite ions.

[0017] Item 5. The filtration lubricant according to any one of Items 1 to 4, further comprising periodate ions.

[0018] Item 6: The filtration smoother according to any one of Items 1 to 5, wherein the filtration smoother is used for treating a semiconductor wafer, and the semiconductor wafer contains at least one metal selected from Ru, Rh, Ti, Ta, Co, Cr, Hf, Os, Pt, Ni, Mn, Cu, Zr, La, Mo, and W.

[0019] Item 7. The filtration lubricant according to any one of Items 1 to 5, wherein the semiconductor wafer contains Ru.

[0020] Item 8. A method for etching a semiconductor wafer, comprising a step of contacting the filtration smoothing agent according to any one of items 1 to 7 with a semiconductor wafer.

[0021] Item 9. A method for manufacturing a semiconductor device, comprising the steps of filtering the filtration lubricant according to any one of items 1 to 7, and subjecting the filtered filtration lubricant to etching of a semiconductor wafer.

[0022] Item 10. The method for manufacturing a semiconductor device according to Item 9, further comprising the step of filtering the filtering lubricant multiple times.

[0023] Item 11. A method for regenerating a used semiconductor processing solution, comprising the step of adding the filtration lubricant according to any one of Items 1 to 7 to a used semiconductor processing solution.

[0024] Item 12. A polishing composition comprising at least one onium ion selected from the group consisting of onium ions represented by the following formulas (1) to (6) and a hypohalite ion: (In formulas (1) to (6), R １ , R ２ , R ３ , R ４ , R ５ , R ６are independently an alkyl group having 2 to 9 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 9 carbon atoms, or an aryl group. In addition, at least one hydrogen atom in the aryl group in the aralkyl group and in 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, and in these groups, at least one hydrogen atom may be replaced by fluorine, chlorine, bromine, or iodine. A is an ammonium ion or a phosphonium ion. Z is an aromatic group or alicyclic group which may contain nitrogen, sulfur, or oxygen atoms, and in the aromatic group or alicyclic group, carbon or nitrogen may have 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 with at least one alkyl group having 1 to 9 carbon atoms, or an alicyclic group which may be substituted with 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 with at least one alkyl group having 1 to 9 carbon atoms, or an alicyclic group which may be substituted with at least one alkyl group having 1 to 9 carbon atoms. n is an integer of 1 or 2 and indicates the number of R. When n is 2, R may be the same or different and may form a ring. a is an integer of 1 to 10.

[0025] Item 13. A polishing composition comprising the filtration lubricant according to any one of Items 4 to 7.

[0026] Item 14. A method for polishing a semiconductor wafer using the polishing composition according to Item 12 or 13, which comprises supplying a polishing composition to a polishing pad containing abrasive grains or a polishing pad not containing abrasive grains, bringing the surface to be polished of the semiconductor wafer into contact with the polishing pad, and polishing the surface by relative movement between the polishing pad and the polishing composition.

[0027] Item 15. A metal recovery agent containing an onium ion coordinated to a metal oxide ion or a metal hydroxide ion.

[0028] Item 16. The metal recovery agent according to item 15, wherein the onium ion is at least one selected from the group consisting of a phosphonium ion and an ammonium ion.

[0029] Item 17. A method for recovering metals from a used semiconductor processing solution, comprising a step of adding the metal recovery agent according to item 15 or 16 to the used semiconductor processing solution.

[0030] According to the present invention, by controlling the surface tension of the filtration lubricant containing an onium salt, it is possible to suppress a decrease in the concentration of the onium salt during the filtration process. Therefore, when this filtration lubricant is used as a semiconductor processing liquid, it is possible to maintain good surface smoothness after etching and further prevent the formation of RuO ４ This suppresses gas generation. Furthermore, since filtration using a fine-mesh filter is possible, particles in the processing solution can be removed, improving the yield of semiconductor wafers. Furthermore, by controlling the surface tension and appropriately controlling the type and concentration of the oxidizing agent and onium salt, it is possible to suppress the deterioration of etching characteristics when the processing solution is reused, enabling significant cost reductions in semiconductor wafer manufacturing.

[0031] 1 is a diagram showing an outline of equipment used in an etching step in a method for manufacturing a semiconductor device.

[0032] (Filtering Lubricant) The filtering lubricant of the present invention is characterized by containing onium ions and having a surface tension of 60 mN / m or more and 75 mN / m or less. The onium ions interact with the metal surface of the semiconductor wafer, making it possible to suppress roughness of the metal surface. In addition, when the semiconductor wafer contains ruthenium, RuO generated during etching of the ruthenium is removed. ４ － and RuO ４ ２－ By interacting with RuO ４ Gas and concomitantly produced RuO ２ Therefore, the filtration lubricant of the present invention can be suitably used as it is as a semiconductor processing liquid in the etching step, residue removal step, cleaning step, CMP step, etc. in the semiconductor manufacturing process.

[0033] As described above, the onium ions contained in the filtration lubricant of the present invention play various roles, but in order to maintain these effects at a high level, the surface tension of the filtration lubricant is the key. That is, if the surface tension of the filtration lubricant is less than 60 mN / m, the onium ions contained in the filtration lubricant are easily removed during the filtration process, and therefore, the good surface smoothness and RuO ４ It becomes difficult to maintain the gas suppression effect. One method for increasing surface tension is to add a salt containing an anion with a high degree of hydration. Adding an anion with a high degree of hydration inhibits the neutralization of the charge of the onium ion by the anion, maintaining the electrical repulsion between the onium ions, thereby increasing the surface tension. Examples of anions with a high degree of hydration include fluoride ions, chloride ions, and bromide ions. On the other hand, if the filtration lubricant of the present invention contains an oxidizing agent, as described below, the stability of the oxidizing agent may decrease due to a reaction between the salt and the oxidizing agent, or etching may be inhibited due to a high concentration of salt. For these reasons, the surface tension is preferably 75 mN / m or less.

[0034] Here, the filtration process will be described. In the manufacture of semiconductor wafers, adhesion of particles to wafers leads to a decrease in yield, so the processing solution is filtered to remove particles from the processing solution. In the case of cutting-edge semiconductor wafers, the wiring width is very narrow, ranging from several nm to several tens of nm, and therefore the pore diameter of the filter used in the filtration process must also be of a similar size. However, the smaller the pore diameter of the filter, the more easily onium salts or onium ions are adsorbed and removed. This reduces the onium ion concentration in the processing solution, impairing its function as a processing solution as described above.

[0035] However, such a decrease in onium ion concentration can be avoided by controlling the surface tension of the filtration lubricant used as a semiconductor processing liquid. Specifically, the surface tension of water is approximately 73 mN / m at 25°C, and adjusting the surface tension to this value can suppress adsorption of onium salts or onium ions to filters. That is, by controlling the surface tension of the filtration lubricant to 60 mN / m or more and 75 mN / m or less, adsorption of onium salts or onium ions to filters can be suppressed, and the filtration lubricant can be used as a processing liquid without losing its functionality. For these reasons, the surface tension is 60 mN / m or more and 75 mN / m or less, preferably 68 mN / m or more and 75 mN / m or less, and most preferably 71 mN / m or more and 73 mN / m or less. Here, the surface tension in this specification is a value at 25°C. The surface tension of the filtration lubricant can be increased by, for example, decreasing the concentration of the onium salt to be added, changing the type of salt containing an anion with a high degree of hydration, or increasing its concentration so that the surface tension falls within an appropriate range. In other embodiments described below, the surface tension can be adjusted in the same manner.

[0036] (Onium ion) The surface tension is affected by the onium ion contained in the filtration lubricant of the present invention. Therefore, by appropriately selecting the type and concentration of the onium ion, it is possible to maintain the surface tension within an appropriate range. In order to maintain the surface tension within a preferred range, it is preferable to select one or more types selected from the group consisting of onium ions having structures represented by the following formulas (1) to (6).

[0037] (In formulas (1) to (6), R １ , R ２ , R ３ , R ４ , R ５ , R ６are independently an alkyl group having 2 to 9 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 9 carbon atoms, or an aryl group. In addition, at least one hydrogen atom in the aryl group in the aralkyl group and in 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, and in these groups, at least one hydrogen atom may be replaced by fluorine, chlorine, bromine, or iodine. Counter anions for the onium ions include fluoride, chloride, bromide, iodide, hydroxide, nitrate, phosphate, sulfate, hydrogen sulfate, methanesulfate, perchlorate, chlorate, chlorite, hypochlorite, orthoperiodate, metaperiodate, iodate, iodite, hypoiodite, acetate, carbonate, hydrogen carbonate, fluoroborate, and trifluoroacetate. A is an ammonium ion or a phosphonium ion. Z is an aromatic group or alicyclic group which may contain nitrogen, sulfur, or oxygen atoms, and in the aromatic group or alicyclic group, carbon or nitrogen may have 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 with at least one alkyl group having 1 to 9 carbon atoms, or an alicyclic group which may be substituted with 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 with at least one alkyl group having 1 to 9 carbon atoms, or an alicyclic group which may be substituted with at least one alkyl group having 1 to 9 carbon atoms. n is an integer of 1 or 2 and indicates the number of R. When n is 2, R may be the same or different and may form a ring. a is an integer of 1 to 10.

[0038] The longer the hydrocarbon group represented by R in the formula, the more hydrophobic it becomes. Therefore, the longer the chain of the onium ion containing the hydrocarbon group, the lower the surface tension of the filtration lubricant tends to be. On the other hand, if the hydrocarbon chain is too short, the effect of the onium ion, such as improving the surface smoothness, and the effect of RuO ４ For this reason, it is preferable that the number of carbon atoms in the hydrocarbon group is within the above range.

[0039] The concentration of the onium ions in the filtration smoothing agent of the present invention is preferably 1 mass ppm or more and 10,000 mass ppm or less. If the amount of onium ions added is too small, when the agent is used as a semiconductor processing solution, RuO ４ － The interaction with RuO ４ Not only does the gas suppression effect decrease, but the amount of onium ions adhering to the metal surface during etching becomes insufficient, which tends to reduce surface smoothness. On the other hand, if the amount added is too large, the amount of onium ions adsorbed to the metal surface becomes excessive, resulting in a decrease in the etching rate. In addition, when an oxidizing agent is contained in the filtration smoothing agent, the reaction between the oxidizing agent and the onium ions may cause a decrease in the concentration of the oxidizing agent. Therefore, the filtration smoothing agent of the present invention preferably contains onium ions in an amount of 1 mass ppm to 10,000 mass ppm, more preferably 10 mass ppm to 5,000 mass ppm, and even more preferably 50 mass ppm to 2,000 mass ppm. When onium ions are added, only one type may be added, or two or more types may be added in combination. Even when two or more types of onium ions are contained, as long as the total concentration of the onium ions is within the above concentration range, RuO ４ Gas generation can be effectively suppressed.

[0040] Examples of such onium ions include 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-onium 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'-bipyridinium bis(tetrafluoroborate), benzyltributylammonium ion, trimethylphenylammonium ion, 5-azoniaspiro[4.4]nonane ion, tributylmethylammonium ion, tetrabutylammonium ion, tetrapentylammonium ion, tetrabutylphosphonium ion, diallyldimethylammonium ion, 1,Examples thereof include 1-dimethylpiperidinium ion, (2-hydroxyethyl)dimethyl(3-sulfopropyl)ammonium hydroxide, 3-(trifluoromethyl)phenyltrimethylammonium ion, 1,1'-(decane-1,10-diyl)bis[4-aza-1-azoniabicyclo[2.2.2]octane]diion, (3-bromopropyl)trimethylammonium ion, vinylbenzyltrimethylammonium ion, allyltrimethylammonium ion, trimethylvinylammonium ion, choline ion, β-methylcholine ion, and triphenylsulfonium ion, and preferably benzyldimethylphenyl ion. and at least one selected from the group consisting of a phenylammonium ion, a 1-ethoxy-1-oxopropan-2-yl)triphenylphosphonium ion, a 1,1'-(decane-1,10-diyl)bis[4-aza-1-azoniabicyclo[2.2.2]octane]diion, a butyltriphenylphosphonium ion, a (2-carboxyethyl)triphenylphosphonium ion, a (3-carboxypropyl)triphenylphosphonium ion, a (4-carboxybutyl)triphenylphosphonium ion, an allyltriphenylphosphonium ion, a tetraphenylphosphonium ion, and a benzyltriphenylphosphonium ion.

[0041] As described above, the effects of onium ions are to suppress surface roughness during etching, ４ In addition to the above, there is also an effect of increasing the number of times of reuse when used as a semiconductor processing solution. In semiconductor wafer manufacturing plants, from the viewpoint of cost reduction, it is common to recycle and reuse used processing solutions. In this case, for example, during etching, metals are dissolved into the processing solution, so the composition of the processing solution before and after use is different. Taking the etching of ruthenium with hypobromite ions as an example, ruthenium becomes RuO under alkaline conditions. ４ － In this case, this RuO ４ － or RuO ４ － is changed to form RuO ４ ２－ and RuO４ When hypobromite ions react with HCl, the concentration of hypobromite ions, which are effective chemical species for etching, decreases. Therefore, the etching rate decreases as the number of times the treatment solution is reused increases and as the reuse time increases.

[0042] However, by incorporating an onium ion into the filtration lubricant, the stability during reuse when used as a semiconductor processing solution can be improved in some cases. ４ － etc. reacts positively with onium ions, ４ － It is possible to suppress the reaction of hypobromite ions with the like. As an onium ion that can be used for such a purpose, a phosphonium ion is preferable. In the case of ammonium ions, there is a concern that an amine will be generated by reaction with hypobromite ions, and this amine may decompose hypobromite ions. In addition, phosphonium ions generally have a larger molecular size than ammonium ions, and RuO generated by dissolution ４ － Since it is easy to form an ion pair with RuO ４ － By binding RuO ４ － This also has the effect of suppressing the reaction between the bromine ion and the hypobromite ion.

[0043] Examples of such onium ions include an allyltriphenylphosphonium ion, a tetraphenylphosphonium ion, a trans-2-butene-1,4-bis(triphenylphosphonium ion), a benzyltriphenylphosphonium ion, a tetrabutylphosphonium ion, a tributylhexylphosphonium ion, a heptyltriphenylphosphonium ion, a cyclopropyltriphenylphosphonium ion, a (bromomethyl)triphenylphosphonium ion, and a (chloromethyl)triphenylphosphonium ion.

[0044] (Hypobromite ion and hypochlorite ion) The filtration lubricant of the present invention may contain an oxidizing agent. By incorporating an oxidizing agent, it is possible to add the function of removing metals contained in semiconductor wafers, and thus the filtration lubricant can be used as a semiconductor processing solution as is. The filtration lubricant can be suitably used in etching and cleaning processes for metal-containing semiconductor wafers. The type of oxidizing agent is not particularly limited, and examples thereof include hydrogen peroxide, ozone, hypochlorous acid, chlorous acid, chloric acid, perchloric acid, hypobromous acid, bromous acid, bromic acid, perbromic acid, hypoiodous acid, iodous acid, iodic acid, periodic acid, salts thereof, and ions generated by dissociation of these salts, as well as one or more selected from the group consisting of hydrogen peroxide, ozone, fluorine, chlorine, bromine, iodine, permanganate, chromate, dichromate, and cerium salt. Among these, hypobromite ion, hypochlorite ion, and periodate ion are preferred because of their strong oxidizing power, stability, and suitability for semiconductor applications, and hypobromite ion is most preferred. Here, the periodate ion is orthoperiodate ion or metaperiodate ion.

[0045] For example, when hypobromite ions or periodate ions are added to the filtration lubricant of the present invention, their concentration is not particularly limited as long as it does not deviate from the object of the present invention, but is preferably 0.001 mol / L or more and 0.20 mol / L or less in either case. If the concentration is less than 0.001 mol / L, the metal etching rate is low and practicality is low. On the other hand, if the concentration exceeds 0.20 mol / L, decomposition of hypobromite ions is likely to occur, making it difficult to stabilize the metal etching rate. In order to stably etch metal at a sufficient rate, the concentration of the hypobromite ions is preferably 0.001 mol / L or more and 0.20 mol / L or less, more preferably 0.005 mol / L or more and 0.20 mol / L or less, and most preferably 0.01 mol / L or more and 0.10 mol / L or less.

[0046] The mechanism by which an oxidizing agent etches a metal will be explained using an example in which the oxidizing agent is hypobromite ions and the metal is ruthenium. In the filtration lubricant, hypobromite ions oxidize ruthenium to form RuO４ , RuO ４ － or RuO ４ ２－ It is presumed that ruthenium is dissolved in the filtration lubricant by using RuO ４ － or RuO ４ ２－ By dissolving it as RuO ４ Reduces gas generation and RuO ２ It is possible to suppress the generation of particles. ４ － or RuO ４ ２－ In order to dissolve ruthenium as RuO, the pH of the filtration lubricant is preferably alkaline, more preferably from 8 to 14, even more preferably from 12 to 14, and most preferably from 12 to less than 13. When the pH of the filtration lubricant is from 12 to less than 13, ruthenium dissolves in RuO. ４ － or RuO ４ ２－ RuO ４ The amount of gas generated is significantly reduced, and RuO ２ On the other hand, when the pH of the filtration lubricant is less than 8, ruthenium is converted into RuO ２ and RuO ４ RuO ２ As the amount of particles increases, RuO ４ Furthermore, if the pH exceeds 14, it becomes difficult to dissolve ruthenium, making it difficult to obtain a sufficient ruthenium etching rate, which reduces the production efficiency in semiconductor manufacturing.

[0047] The filtration lubricant of the present invention may contain one or more oxidizing agents. The inclusion of multiple oxidizing agents may stabilize the etching rate or improve the stability of the filtration lubricant when reused. For example, when hypobromite ions are included as the first oxidizing agent, the hypobromite ions consumed in metal etching lose their oxidizing power and convert to bromide ions. In this case, the greater the amount converted to bromide ions, the lower the etching rate when used as a semiconductor processing solution. In semiconductor wafer manufacturing plants, processing solutions are typically recycled and reused to reduce costs. However, if the etching rate decreases due to the reuse of the processing solution, it becomes difficult to stably manufacture semiconductor wafers. On the other hand, when the filtration lubricant contains multiple oxidizing agents, for example, when hypochlorite ions are included in addition to hypobromite ions, the bromide ions that have lost their oxidizing power are oxidized by hypochlorite ions and converted to hypobromite ions. Therefore, it is possible to suppress a decrease in the concentration of hypobromite ions in the filtration lubricant, and even when the filtration lubricant is reused, a decrease in the etching rate is unlikely to occur.

[0048] For the above reasons, when the filtration lubricant of the present invention contains hypobromite ions, it is preferable that hypochlorite ions coexist in the filtration lubricant.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 preferable that it is 0.001 mol / L or more and 0.2 mol / L or less.If the concentration of hypochlorite ions is less than 0.001 mol / L, Br － The ruthenium etching rate decreases because the amount of hypochlorite ions added is insufficient to efficiently oxidize the ruthenium. On the other hand, if the amount of hypochlorite ions added is greater than 0.2 mol / L, the stability of the hypochlorite ions decreases and the decomposition of hypobromite ions due to the reaction between hypochlorite ions and hypobromite ions is promoted, which is not appropriate. The concentration of hypochlorite ions is more preferably 0.005 mol / L or more and 0.10 mol / L or less, and most preferably 0.01 mol / L or more and 0.05 mol / L or less.

[0049] (Others) If desired, the filtration lubricant of the present invention may contain other additives that have been conventionally used in semiconductor processing solutions, as long as they do not impair the object of the present invention.For example, as other additives, acids, metal corrosion inhibitors, water-soluble organic solvents, fluorine compounds, oxidizing agents, reducing agents, complexing agents, chelating agents, surfactants, antifoaming agents, pH adjusters, stabilizers, etc. may be added.These additives may be added alone or in combination.

[0050] In order to adjust the pH of the filtration lubricant, an acid or alkali can be added to the filtration lubricant. As the alkali, it is preferable to use an organic alkali because it does not contain metal ions that cause problems in semiconductor manufacturing. Among them, the organic alkali is preferably tetraalkylammonium hydroxide, and more preferably tetramethylammonium hydroxide, because it has a large number of hydroxide ions per unit weight and high-purity products are easily available.

[0051] Due to these additives and for reasons of convenience in manufacturing the filtration lubricant, the filtration lubricant of the present invention may contain alkali metal ions, alkaline earth metal ions, etc. However, if these alkali metal ions and alkaline earth metal ions remain on the semiconductor wafer, they may cause a decrease in the yield of semiconductor elements, etc. Therefore, the content of metals in the filtration lubricant of the present invention, specifically, for example, any metal selected from lithium, sodium, potassium, aluminum, magnesium, calcium, chromium, manganese, iron, nickel, cobalt, copper, silver, cadmium, barium, zinc, and lead, is preferably 1 ppb or less by mass, more preferably 0.5 ppb or less, even more preferably 0.2 ppb or less, and most preferably 0.1 ppb or less. Furthermore, among the above metals, the concentration of any one metal selected from iron, copper, and zinc is preferably 0.01 ppt to 1 ppb by mass, more preferably 0.01 ppt to 0.5 ppb, even more preferably 0.01 ppt to 0.2 ppb, and most preferably 0.01 ppt to 0.1 ppb. Furthermore, although ionic metals have been mentioned above as metals that may be contained in the filtration lubricant of the present invention, this is not limiting, and non-ionic metals (particulate metals) may also be contained. When a particulate metal is contained alone, its concentration is preferably within the above range. When an ionic metal and a particulate metal are contained, the total of their concentrations is preferably within the above range.

[0052] The water contained in the filtration lubricant of the present invention is preferably water from which metal ions, organic impurities, particles, etc. have been removed by distillation, ion exchange treatment, filter treatment, various adsorption treatments, etc., and pure water or ultrapure water is particularly preferred. Such water can be obtained by known methods widely used in semiconductor manufacturing.

[0053] The filtration lubricant of the present invention is preferably stored at low temperature and / or protected from light. Storage at low temperature and / or protected from light is expected to suppress decomposition of the oxidizing agent, onium ions, and the like in the filtration lubricant. Furthermore, storing the filtration lubricant in a container filled with an inert gas to prevent carbon dioxide contamination maintains the stability of the filtration lubricant. Furthermore, the inner surface of the container, i.e., the surface that comes into contact with the filtration lubricant, is preferably made of glass or an organic polymer material. Forming the inner surface of the container from glass or an organic polymer material further reduces the inclusion of impurities such as metals, metal oxides, and organic substances. The filtration lubricant of the present invention is a chemical solution that reduces the capture of onium salts by filters during the filtration process included in the manufacturing method of semiconductor devices. In other words, it can be said to be an agent that reduces the capture of onium salts by filters.

[0054] (Method for Etching Semiconductor Wafer) When the filtration smoothing agent of the present invention is used for processing semiconductors, the semiconductor wafer to which it is applied preferably contains at least one metal selected from Ru, Rh, Ti, Ta, Co, Cr, Hf, Os, Pt, Ni, Mn, Cu, Zr, La, Mo, and W. These metals are formed into a film on the semiconductor wafer by a method widely known in the semiconductor manufacturing process, such as CVD, ALD, PVD, sputtering, plating, etc. The filtration smoothing agent of the present invention contains onium ions, thereby forming RuO ４ Among these metals, ruthenium is particularly suitable for use because of its gas suppressing effect. Ruthenium is not limited to metallic ruthenium, and may contain 70 atomic % or more of ruthenium, and also includes ruthenium alloys, ruthenium oxides (ruthenium dioxide, ruthenium trioxide, etc.), nitrides, oxynitrides, intermetallic compounds, ionic compounds, complexes, etc.

[0055] The filtration lubricant of the present invention can be brought into contact with a semiconductor wafer to etch the semiconductor wafer. In other words, the semiconductor wafer etching method of the present invention includes a step of contacting the filtration lubricant with the semiconductor wafer. The filtration lubricant of the present invention can be used as a semiconductor processing solution as is, and when it contains the oxidizing agent described above, it can be preferably used as an etching solution for semiconductor wafers. When the filtration lubricant is used as an etching solution, the type of oxidizing agent and the concentration of the oxidizing agent in the filtration lubricant described above can be applied. Furthermore, the other conditions for the filtration lubricant can also be applied as described above. A wet etching process for ruthenium using the filtration lubricant of the present invention will be described as an example. First, a substrate made of a semiconductor (e.g., Si) is prepared. The prepared substrate is subjected to an oxidation treatment to form a silicon oxide film on the substrate. Then, an interlayer insulating film made of a low-k film is formed, and via holes are formed at predetermined intervals. After the via holes are formed, a ruthenium film is formed by thermal CVD. This ruthenium film is etched using the filtration lubricant of the present invention to form RuO. ４ It is possible to form ruthenium wiring with excellent surface smoothness in the via hole while suppressing gas generation.

[0056] The temperature when etching ruthenium using the filter lubricant of the present invention as a semiconductor processing solution is not particularly limited. ４ The amount of gas generated can be determined by taking into consideration the amount of gas generated. ４ The amount of gas increases, and the stability of hypobromite ions also decreases. On the other hand, the etching rate tends to decrease as the temperature decreases. For these reasons, the temperature for etching ruthenium is preferably 10°C to 90°C, more preferably 15°C to 60°C, and most preferably 25°C to 45°C.

[0057] (Method for Manufacturing Semiconductor Devices) The method for manufacturing semiconductor devices of the present invention includes a step of filtering the above-mentioned filtration lubricant and a step of subjecting the filtered filtration lubricant to etching of a semiconductor wafer. The filtration lubricant of the present invention can be used as is in the method for manufacturing semiconductor devices. Furthermore, the conditions described above can be applied to the etching step as they are. The metal to be etched can also be the same as above. To etch a semiconductor wafer, it is preferable that the filtration lubricant contains the oxidizing agent listed above. The type of oxidizing agent and the concentration of the oxidizing agent in the filtration lubricant can be the same as those described above. The surface tension of the filtration lubricant at 25°C is 60 mN / m or more and 75 mN / m or less, and the preferred range is the same as the conditions described above. Furthermore, the other conditions for the filtration lubricant can be applied as well.

[0058] Referring to FIG. 1 , during the manufacturing of semiconductor devices, the filtration lubricant may pass through filters 1 and 2 or 3. When valve 10 in FIG. 1 is closed and valve 9 is opened, the chemical solution in chemical cabinet 6 is filtered by passing it through filters 1 and 2 by driving pump 4. To remove as many impurities as possible from the chemical solution in chemical cabinet 6, the filtration process of passing the chemical solution through filters 1 and 2 may be performed multiple times. The number of filters passed during each filtration process may be, for example, one or more, such as two, three, or four or more. When valve 10 in FIG. 1 is opened, the chemical solution in chemical cabinet 6 is supplied to etching table 8 by driving pump 4, and the semiconductor wafer is etched. Furthermore, to replenish the chemical solution in chemical cabinet 6, the chemical solution in the chemical solution replenishment unit is passed through filter 3 by driving pump 5 and replenished into chemical cabinet 6. Note that the chemical solution described here may be the filtration lubricant itself, or it may be a chemical solution obtained by adding the filtration lubricant to a different chemical solution. When the filtration lubricant is added to a chemical solution separate from the filtration lubricant, the surface tension of the mixed chemical solution is adjusted to the range described above. The preferred range of the surface tension of the mixed chemical solution is also the same as the range described above. The semiconductor device manufacturing method may include known processes used in semiconductor device manufacturing methods, such as one or more processes selected from a wafer fabrication process, an oxide film formation process, a transistor formation process, a wiring formation process, and a CMP process. The semiconductor device manufacturing method of the present invention may also include a method for recovering metals from used semiconductor processing solutions, as described below, as one step. Specifically, the semiconductor device manufacturing method of the present invention may include a process for recovering processing solutions after etching a semiconductor wafer, a process for adding a metal recovery agent, described below, to the recovered processing solutions, and a process for filtering the processing solutions to which the metal recovery agent has been added, thereby resulting in a manufacturing method that recovers metals from the processing solutions.

[0059] (Method for Producing a Filtration Smoothener) In another embodiment of the present invention, a method for producing a filtration smoothener is provided. In the method for producing a filtration smoothener, at least onium ions and water are mixed and prepared so that the surface tension at 25°C is 60 mN / m or more and 75 mN / m or less (25°C). In the production method of this embodiment, the conditions for the type and concentration of the onium ions used in the filtration smoothener listed above can be applied as they are. The surface tension of a solution containing onium ions and water can be adjusted, for example, by adjusting the type and concentration of the onium ions. The preferred range for the surface tension of the prepared filtration smoothener can be applied as it is to the range described above. When an oxidizing agent is added to the filtration smoothener, it may be added when the onium ions and water are mixed, or the oxidizing agent may be added to a solution in which the onium ions and water are mixed in advance. The conditions for the type and concentration of the oxidizing agent described above can be applied as they are. In addition, the conditions for other additives contained in the filtration smoothener can also be applied as they are to the contents described above.

[0060] (Method for Reclaiming Used Semiconductor Processing Solution) Another embodiment of the present invention includes a step of adding the above-described filtration lubricant to a used semiconductor processing solution (hereinafter, also referred to simply as the reclaiming method). In the reclaiming method of the present invention, a used semiconductor processing solution is the target for reclaiming. Here, the used semiconductor processing solution refers to a chemical solution that has been used at least once for processing, such as etching, in the manufacture of semiconductor wafers, for example. Therefore, the used semiconductor processing solution may contain an oxidizing agent. Examples of the oxidizing agent include those types mentioned in the description of the filtration lubricant. Furthermore, the surface tension at 25°C of the reclaimed semiconductor processing solution after adding the above-described filtration lubricant may be adjusted to 60 mN / m or more and 75 mN / m or less. By adjusting the surface tension to such a level, when the reclaimed semiconductor processing solution is used in a semiconductor device manufacturing method, the reduction of onium ions during the filtration step can be suppressed. To adjust the surface tension of the reclaimed semiconductor processing solution, the type and concentration of onium ions contained in the added filtration lubricant may be adjusted. The type of onium ions in the added filtration lubricant can be determined as described in the section on the filtration lubricant. It is also preferable to adjust the concentration of onium ions in the filtration lubricant to be added so that the concentration of onium ions contained in the chemical solution after regeneration falls within the range explained for the filtration lubricant above.

[0061] (Polishing Composition) The polishing composition of the present invention is characterized by containing one or more onium ions selected from the group consisting of onium ions represented by the following formulas (1) to (6), and is capable of polishing semiconductor wafers containing metals or metal oxides to flatness and smoothness while maintaining a high removal rate, although not limited thereto.

[0062] (In formulas (1) to (6), R １ , R ２ , R ３ , R ４ , R ５ , R ６are independently an alkyl group having 2 to 9 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 9 carbon atoms, or an aryl group. In addition, at least one hydrogen atom in the aryl group in the aralkyl group and in 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, and in these groups, at least one hydrogen atom may be replaced by fluorine, chlorine, bromine, or iodine. Counter anions for the above onium ions include fluoride ion, chloride ion, bromide ion, iodide ion, hydroxide ion, nitrate ion, phosphate ion, sulfate ion, hydrogen sulfate ion, methanesulfate ion, perchlorate ion, chlorate ion, chlorite ion, hypochlorite ion, orthoperiodate ion, metaperiodate ion, iodate ion, iodite ion, hypoiodite ion, acetate ion, carbonate ion, hydrogen carbonate ion, fluoroborate ion, and trifluoroacetate ion. A is an ammonium ion or a phosphonium ion. Z is an aromatic group or alicyclic group which may contain nitrogen, sulfur, or oxygen atoms, and in the aromatic group or alicyclic group, carbon or nitrogen may have 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 with at least one alkyl group having 1 to 9 carbon atoms, or an alicyclic group which may be substituted with 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 with at least one alkyl group having 1 to 9 carbon atoms, or an alicyclic group which may be substituted with at least one alkyl group having 1 to 9 carbon atoms. n is an integer of 1 or 2 and indicates the number of R. When n is 2, R may be the same or different and may form a ring. a is an integer of 1 to 10.

[0063] By including such onium ions in the polishing composition, the onium ions generated by dissociation of the onium ions interact with the metal or metal oxide to be polished, thereby obtaining a smooth polished surface. Examples of such onium ions include the compounds described in the filtration lubricant of the present invention, and the preferred range of the onium ion concentration is also the same. The surface tension of the polishing composition of the present invention at 25°C may be 60 mN / m or more and 75 mN / m or less. The surface tension of the polishing composition at 25°C may be 68 mN / m or more and 75 mN / m or less, or 71 mN / m or more and 73 mN / m or less. When the surface tension of the polishing composition is within these ranges, a sufficient polishing rate can be obtained for the polishing target, and the surface smoothness of the polishing target can also be finished to a desirable state.

[0064] The polishing composition of the present invention may contain an oxidizing agent. The oxidizing agent is not particularly limited. However, when polishing a material with high hardness and high chemical stability, it is preferable to select a hypohalite ion with high oxidizing power, especially a hypochlorite ion or a hypobromite ion, in order to obtain a sufficiently high removal rate. In this case, the counter ion (cation) is preferably a quaternary ammonium ion such as a tetramethylammonium ion, since this can suppress the metal content. When hypohalite ions are added as an oxidizing agent, their concentration is not particularly limited. However, if the concentration is too low, the removal rate decreases, and if the concentration is too high, the concentration changes significantly due to decomposition of the hypohalite ions. For these reasons, when hypohalite ions are added as an oxidizing agent, the concentration of the hypohalite ions is preferably 0.001 mol / L or more and 0.20 mol / L or less, more preferably 0.005 mol / L or more and 0.20 mol / L or less, and most preferably 0.01 mol / L or more and 0.10 mol / L or less. The same concentration ranges can be applied when the hypohalite ions are one or more selected from hypochlorite ions and hypobromite ions. Furthermore, the concentrations of halate ions, haloid ions, and halide ions generated by consumption of hypohalite ions during polishing or by natural decomposition during storage are each preferably 0.00001 mol / L or more and 0.10 mol / L or less, more preferably 0.00001 mol / L or more and 0.02 mol / L or less, and most preferably 0.00001 mol / L or more and 0.01 mol / L or less.

[0065] (pH) The pH of the polishing composition of the present invention is preferably 7 or more and 14 or less from the viewpoint of polishing characteristics and stability. If it is less than 7, the polishing rate may decrease and become unstable. For example, when hypohalite ions are contained as an oxidizing agent, if the pH is less than 7, the hypohalite ions may decompose. If it is less than 7, metal-containing particles may be more likely to remain on the semiconductor wafer surface, which tends to increase the amount of metal remaining on the wafer after polishing. From this viewpoint, the pH is preferably 7 or more. If colloidal silica is used as the abrasive, the colloidal silica may dissolve at a pH of 13 or more. For these reasons, the pH is preferably 7 or more and 14 or less, more preferably 9 or more and 13 or less, and most preferably 11 or more and 12.5 or less.

[0066] (Abrasive) When the polishing composition of the present invention contains abrasive grains, known abrasive grains can be used without any particular limitation. Preferred abrasive grains include silicon oxide (silica) particles, diamond particles, cerium oxide (ceria) particles, aluminum oxide (alumina) particles, zirconium oxide (zirconia) particles, and titanium oxide (titania) particles. The concentration of these abrasives is not particularly limited, but if the concentration is too low, the polishing rate decreases, and if the concentration is too high, the abrasive grains aggregate, causing a deterioration in surface smoothness. Therefore, the concentration is preferably 0.02 to 10.0 mass%, more preferably 0.5 to 5.0 mass%.

[0067] (Polishing method) The polishing method using the polishing composition of the present invention can be carried out using a single-sided or double-sided polishing machine. As an example of the polishing device, a polishing device equipped with a rotary table for fixing a surface plate, a wafer holder for holding a semiconductor wafer to be polished, and a pressure unit having a rotating mechanism for rotating the held wafer and pressing it against the polishing surface of the surface plate with a predetermined polishing load can be used.

[0068] For example, polishing can be performed by a method in which the polishing composition of the present invention to which abrasive grains have been added is applied, sprayed, or dropped onto a semiconductor wafer to be polished, and the wafer is brought into contact with a polishing pad (sheet) containing no abrasive grains, followed by polishing with the relative movement of the two, or by a method in which the polishing composition of the present invention is applied, sprayed, or dropped onto a semiconductor wafer to be polished, and the wafer is brought into contact with a polishing pad (sheet) having abrasive grains fixed thereto, followed by polishing with the relative movement of the two. The semiconductor wafer to be polished using the polishing liquid of the present invention is, for example, a semiconductor wafer containing Ru, Rh, Ti, Ta, Co, Cr, Hf, Os, Pt, Ni, Mn, Cu, Zr, La, Mo, W, etc. as the object to be polished.

[0069] (Others) The polishing composition of the present invention may contain, as needed, lubricants, viscosity imparting agents, viscosity modifiers, rust inhibitors, etc., as long as such additions do not violate the spirit of the present invention. For example, the polishing composition can be prepared by mixing abrasive grains (silica), an oxidizing agent (hypobromite ion), a pH adjuster (tetramethylammonium hydroxide), and ultrapure water.

[0070] (Metal Recovery Agent) The metal recovery agent of the present invention is characterized by containing one or more onium ions selected from onium ions coordinated to metal oxide ions and metal hydroxide ions. The metal oxide ions or metal hydroxide ions form an ion complex with the onium ions to generate an insoluble salt, which can be recovered by filtration or other methods to recover the metal. The onium ions coordinated to the metal oxide ions or metal hydroxide ions are preferably phosphonium ions, sulfonium ions, or ammonium ions, and more preferably phosphonium ions or ammonium ions that form stable ion complexes with the metal oxide ions. More specifically, the onium ions may be one or more selected from the group consisting of onium ions represented by formulas (1) to (6) described in the section on the filtration lubricant. The metal oxide ions or metal hydroxide ions are metal oxides or metal hydroxide ions that have a negative charge in solution. Specifically, they are oxide ions or hydroxide ions of Ru, Ta, Co, Cr, Os, Ni, Mn, Cu, Zr, Mo, or W. Adding onium ions to a solution containing these ions forms an ion complex with metal oxide ions or metal hydroxide ions, producing an insoluble salt. The types of onium ions can be the same as those described for the filtration lubricant. The types of counter ions of the onium ions can also be the same as those described for the filtration lubricant. The metal recovery agent preferably contains onium ions at a concentration of, for example, 1 ppm by mass to 50% by mass, more preferably 10 ppm by mass to 10% by mass, even more preferably 50 ppm by mass to 10,000 ppm by mass, and most preferably 100 ppm by mass to 5,000 ppm by mass. This concentration range is also applicable when the onium ions are one or more selected from the group consisting of onium ions represented by formulas (1) to (6). The surface tension of the metal recovery agent at 25°C may be 60 mN / m to 75 mN / m.The surface tension of the polishing composition at 25° C. may be 68 mN / m or more and 75 mN / m or less, or 71 mN / m or more and 73 mN / m or less. When the surface tension of the metal recovery agent is within these ranges, it becomes possible to reuse the used metal recovery agent after metal recovery by filtration or the like as a metal recovery agent.

[0071] (Method for recovering metals from used semiconductor processing solution) Another embodiment of the present invention is a method for recovering metals from used semiconductor processing solution (hereinafter simply referred to as a recovery method), comprising adding the above-described metal recovery agent to the used semiconductor processing solution. The recovery method of the present invention is directed to recovering metals from used semiconductor processing solution. Here, the used semiconductor processing solution refers to a chemical solution that has been used at least once for etching or other processes in the manufacture of semiconductor wafers. Therefore, the used semiconductor processing solution may contain an oxidizing agent. Examples of oxidizing agents include those listed in the description of the filtration lubricant. Adding the metal recovery agent to the used semiconductor processing solution precipitates insoluble salts containing metals, which can be recovered by filtering the precipitated salts. Filters made of organic polymeric materials or inorganic materials are preferably used for metal filtration. For example, filters made of polyolefin (polypropylene, polyethylene, ultra-high molecular weight polyethylene), polysulfone, cellulose acetate, polyimide, polystyrene, fluorine-based resins, and / or quartz fiber can be used. The fluororesin is not particularly limited as long as it is a resin (polymer) containing fluorine atoms, and known fluororesins can be used. Examples include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-ethylene copolymer, chlorotrifluoroethylene-ethylene copolymer, and cyclized polymer of perfluoro(butenyl vinyl ether). The pore size of the filter is not particularly limited, but a filter having a pore size of 1 μm or more or a microfiltration filter can be used to remove coarse particles. On the other hand, a microfiltration filter, an ultrafiltration filter, or a nanofiltration membrane having a pore size of 0.001 μm or more but less than 1 μm can be used to remove fine particles.When the manufacturing method of semiconductor devices includes the above-mentioned recovery method as a series of steps, for example, the steps of recovering the used semiconductor processing liquid, adding a metal recovery agent to the recovered processing liquid, and filtering the used semiconductor processing liquid to which the metal recovery agent has been added may be combined. Alternatively, the metal recovery agent may be added to the semiconductor processing liquid in advance to precipitate insoluble salts containing metals in the used semiconductor processing liquid, which may then be recovered in a subsequent filtration step. In these cases, the used semiconductor processing liquid after metal recovery can be reused as a semiconductor processing liquid.

[0072] The salt of the metal oxide ion or metal hydroxide ion and the onium ion recovered by the filtration filter can be eluted into a solvent capable of dissolving the salt by passing the solvent through the filtration filter. Examples of solvents capable of dissolving the salt include, but are not limited to, water, acids, alkalis, alcohols, ethers, ketones, nitriles, amines, amides, carboxylic acids, and aldehydes. Examples of such solvents include hydrochloric acid, sulfuric acid, nitric acid, aqueous ammonia, tetramethylammonium hydroxide, ethyltrimethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, methanol, ethanol, propanol, butanol, tetrahydrofuran, 1,4-dioxane, acetone, 4-methyl-2-pentanone, acetylacetone, acetonitrile, propylonitrile, butyronitrile, isobutyronitrile, benzonitrile, ethylenediamine, pyridine, formamide, N-methylformamide, N,N-dimethylformamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpropylammonium hydroxide, ... Examples of suitable solvents include propionamide, dimethyl sulfoxide, sulfolane, dimethylthioformamide, N-methylthiopyrrolidone, nitromethane, nitrobenzene, ethyl acetate, methyl acetate, acetic acid, formic acid, lactic acid, glycolic acid, 2,2-bis(hydroxymethyl)propionic acid, gluconic acid, α-glucoheptonic acid, heptanoic acid, phenylacetic acid, phenylglycolic acid, benzilic acid, gallic acid, cinnamic acid, naphthoic acid, anisic acid, salicylic acid, cresotic acid, acrylic acid, monocarboxylic acids such as benzoic acid, malic acid, adipic acid, succinic acid, maleic acid, tartaric acid, oxalic acid, glutaric acid, malonic acid, 1,3-adamantanedicarboxylic acid, diglycolic acid, and phthalic acid, but are not limited to these. By passing the solvent through the filter, salts trapped in the pores of the filter can be dissolved and removed, allowing the filter to be regenerated.

[0073] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0074] (Evaluation of Surface Tension) Using a surface tensiometer (DY300, manufactured by Kyowa Interface Science Co., Ltd.), the surface tension of the filter lubricant described below that was not subjected to filtration was measured in accordance with JIS 2241 "Test method using a Wilhelmy surface tensiometer."

[0075] (Filtration of filtration lubricant) 2 L of filtration lubricant was filled into a 5 L PFA bottle, and the solution was passed through a filter with a filtration accuracy of 5 nm (SWD03UG54E71-K13C, manufactured by Nippon Pall Corporation) using a diaphragm-type liquid pump (NF100TT 18S, manufactured by KNF Corporation). The solution that passed through the filter was circulated back to the PFA bottle, and the flow was repeated until the entire 2 L of solution had passed through the filter 100 times. The resulting solution was recovered as filtered filtration lubricant.

[0076] (Evaluation of Onium Ion Residual Rate After Filtration) The onium ion concentration in the filtration lubricant before and after filtration was evaluated using a liquid chromatography mass spectrometer (Xevo QTof MS, manufactured by Waters Corporation), and the residual onium salt rate after filtration was evaluated according to the following criteria. In all cases, ratings A to C are acceptable levels, and rating D is unacceptable. A: 100 to 95% B: Less than 95% to 80% C: Less than 80% to 60% (acceptable level) D: <60%

[0077] (Evaluation of Etching Rate) First, an oxide film was formed on a silicon wafer using a batch-type thermal oxidation furnace, and a ruthenium film was formed thereon to a thickness of 1200 Å (±10%) using a sputtering method. Sheet resistance was measured using a four-probe resistance meter (Loresta-GP, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) and converted to film thickness, which was used as the ruthenium film thickness before the etching treatment. Next, 60 mL of the filtration lubricant obtained above after filtration was prepared in a fluororesin container with a lid (94.0 mL PFA container, manufactured by AsOne Co., Ltd.). A 10 × 20 mm ruthenium film piece was immersed in the filtration lubricant at 30°C for 1 minute. After the etching treatment, sheet resistance was similarly measured using the four-probe resistance meter and converted to film thickness, which was used as the ruthenium film thickness after the etching treatment. The change in film thickness before and after the treatment divided by the immersion time was calculated as the etching rate, and the value was evaluated according to the following criteria. In all cases, ratings A to C were acceptable levels, and rating D was unacceptable. A: >50 Å / min B: 50-20 Å / min C: Less than 20 Å / min to 10 Å / min (acceptable level) D: Unable to etch

[0078] (RuO ４ Quantitative analysis of gases) RuO ４ The amount of gas generated was measured using ICP-OES. 5 mL of the filtered filtration lubricant obtained above was placed in a sealed container, and one 10 x 20 mm ruthenium film having a thickness of 1200 Å was immersed in the filtration lubricant at 30°C until all of the ruthenium was dissolved. Thereafter, air was flowed into the sealed container, and the gas phase in the sealed container was bubbled into a container containing an absorbing solution (1 mol / L NaOH), and RuO generated during the immersion was measured. ４ The gas was trapped in the absorbing solution. The complete dissolution of ruthenium on the Si wafer immersed in the filtration lubricant was confirmed by measuring the sheet resistance before and after immersion using a four-point probe resistance meter (Loresta-GP, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) and converting it into film thickness. The amount of ruthenium in the absorbing solution was measured using an ICP-OES (iCAP6500 DUO, manufactured by Thermo Fisher Scientific Co., Ltd.) to determine the RuO ４ The gas amount was converted and evaluated according to the following criteria. In all cases, ratings A to C are acceptable levels, and rating D is unacceptable. A: <5 μg / cm ２B: 5-10μg / cm ２ Less than C: 10 μg / cm ２ ~40 μg / cm ２ or less (acceptable level) D: >40 μg / cm ２

[0079] (Evaluation of surface smoothness after etching) The ruthenium surface was observed before and after etching using a field emission scanning electron microscope (JSM-7800F Prime, manufactured by JEOL Ltd.) to check for the presence or absence of surface roughness, and was evaluated according to the following criteria. Surface roughness was ranked from least to greatest, A to D, with ratings A to C being acceptable levels and rating D being unacceptable. A: No surface roughness was observed B: Some surface roughness was observed C: Roughness was observed over the entire surface, but the roughness was shallow D: Roughness was observed over the entire surface, and the roughness was deep

[0080] (Evaluation of Stability When Reusing Filtration Lubricant) 80 mL of the filtration lubricant obtained after filtration as described above was prepared in a fluororesin container with a lid (manufactured by AsOne, PFA container 94.0 mL). A 10 × 10 mm ruthenium film piece on which a ruthenium film with a thickness of 1200 Å had been formed was immersed in the filtration lubricant at 30°C until the ruthenium film was completely dissolved. Using 40 mL of the filtration lubricant in which the ruthenium film had been dissolved, etching rate 1 was evaluated according to the method described above. The remaining 40 mL was stored at 30°C for one week, and etching rate 2 was similarly evaluated. Etching rate 2 divided by etching rate 1 was defined as the stability of the etching rate when the filtration lubricant was reused, and was evaluated according to the following criteria. If etching rate 1 and etching rate 2 do not change, this means that the performance of the filtration lubricant after reuse is maintained. Even if there is a change, evaluations A to C are acceptable levels, and evaluation D is unacceptable. A: 0.9 or more and 1.1 or less B: More than 1.1 and 1.2 or less, or more than 0.8 and less than 0.9 C: More than 1.2 and 1.3 or more than 0.7 and less than 0.8 (acceptable level) D: More than 1.3 or 0.7 or less

[0081] (Method for calculating hypobromite ion and hypochlorite ion concentrations) The hypobromite ion and hypochlorite ion concentrations were measured using an ultraviolet-visible spectrophotometer (UV-2600, manufactured by Shimadzu Corporation). Calibration curves were prepared using aqueous solutions of hypobromite ion and hypochlorite ion with known concentrations, and the hypobromite ion and hypochlorite ion concentrations in the produced filtration lubricant were determined. The hypobromite ion concentration was determined from the measurement data when the absorption spectrum stabilized after mixing the bromine-containing compound, oxidizing agent, and base compound.

[0082] Examples 1 to 15 and Comparative Examples 1 to 3 (Production of Trimethylammonium Hypochlorite Solution) 209 g of a 25% by mass aqueous solution of tetramethylammonium hydroxide and 791 g of ultrapure water were mixed in a 2 L three-necked glass flask (manufactured by Cosmos Bead Co., Ltd.), and CO ２ A 5.2% by mass aqueous solution of tetramethylammonium hydroxide was obtained, with a content of 0.5 ppm and a pH of 13.8.

[0083] Next, a rotor (manufactured by AsOne, total length 30 mm x diameter 8 mm) was placed in a three-neck flask, a thermometer protection tube (manufactured by Cosmos Bead, bottom-sealed type) and a thermometer were placed in one opening, a chlorine gas cylinder and a nitrogen gas cylinder were connected to the other opening, and the tip of a PFA tube (manufactured by Flon Industries Co., Ltd., F-8011-02) that was connected to a state in which chlorine gas / nitrogen gas could be switched at will was immersed in the bottom of the solution, and the remaining opening was connected to a gas washing bottle (manufactured by 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 poured from the PFA tube at a concentration of 0.289 Pa m ３ / second (at 0°C) for 20 minutes to expel carbon dioxide from the gas phase. At this time, the carbon dioxide concentration in the gas phase was 1 ppm or less.

[0084] Thereafter, a magnetic stirrer (C-MAG HS10, manufactured by AsOne) was placed at the bottom of the three-necked flask and rotated at 300 rpm to stir the contents. While the outer periphery of the three-necked flask was cooled with ice water, chlorine gas (manufactured by Fujiox Co., Ltd., specified purity 99.4%) was introduced at a concentration of 0.059 Pa m ３ / sec (at 0°C) for 180 minutes to obtain a mixed solution of tetramethylammonium hypochlorite aqueous solution (oxidizing agent; equivalent to 3.51% by mass, 0.28 mol / L) and tetramethylammonium hydroxide (equivalent to 0.09% by mass, 0.0097 mol / L). The liquid temperature during the reaction was 11°C.

[0085] (Production of filtration lubricant) The tetramethylammonium hypochlorite solution obtained by the above operation was mixed with predetermined amounts of tetramethylammonium bromide (97% by mass, manufactured by Tokyo Chemical Industry Co., Ltd.), onium salt, high-purity hydrochloric acid (manufactured by Kanto Chemical Co., Ltd.), and ultrapure water to obtain a filtration lubricant having the composition shown in Table 1.

[0086] (Evaluation) Using the produced filtration lubricant, the etching rate of ruthenium, RuO ４ The amount of gas generated, stability of the etching rate, the residual rate of onium salt after filtration, and surface smoothness were evaluated.

[0087] The composition of the treatment liquid (filter lubricant) and the evaluation results are shown in Table 1. As shown in Table 1, in Comparative Examples 1 to 3, the onium salt concentration was significantly reduced by the filtration process, and the surface smoothness was unacceptable. Therefore, the etching rate, surface smoothness, RuO ４ In contrast, it was confirmed that the filtration lubricant of this example satisfied all of these evaluation criteria. In Examples 8 to 12, the stability of the treatment solution during reuse was improved due to the effect of adding hypochlorite ions or phosphonium salt to the filtration lubricant. On the other hand, in Comparative Example 3, in which a phosphonium salt was also added, the surface tension was low and the phosphonium salt was removed by filtration, so no improvement in stability was observed.

[0088]

[0089] Examples 16 to 18 First, an oxide film was formed on a silicon wafer using a batch-type thermal oxidation furnace, and then a ruthenium film of 1200 Å (±10%) was formed thereon using a sputtering method. Next, colloidal silica (average particle size 80 nm, SiO ) was added to 1000 g of a solution having the same composition as in Examples 10 to 12. ２The polishing compositions were then added to the polishing machine under the following conditions: Polishing machine: EJ-380IN manufactured by Engis Corporation; Polishing pressure: 500 gf / cm. ２ Polishing pad: SUBA-800, Nitta Haas Corporation Platen rotation speed: 120 rpm Supply rate of polishing composition: 50 ml / min Polishing time: 10 minutes The sheet resistance of the ruthenium before and after polishing was measured using a four-point probe resistance meter (Loresta-GP, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) and converted into film thickness, and the polishing rate for ruthenium was calculated.

[0090] When the polishing compositions described in Examples 16 to 18 were used, the polishing rate of the ruthenium-containing wafer was 10 nm / min, which was sufficient. Furthermore, SEM observation of the polished surface confirmed that good surface smoothness was obtained.

[0091] Examples 19 and 20 A treatment solution containing hypobromite ions was prepared in the same manner as in Example 1 to have the composition shown in Table 2. A 10 × 10 mm ruthenium film piece, on which a ruthenium film with a thickness of 1,200 Å had been formed, was immersed in the resulting treatment solution until the ruthenium film was completely dissolved. A metal recovery agent having the composition shown in Table 2 was added to the treatment solution in which the ruthenium film had been dissolved. The treatment solution to which the metal recovery agent had been added was passed through a polytetrafluoroethylene "Fluoroguard ATX filter (pore size: 0.05 μm)" manufactured by Nippon Entegris Co., Ltd. The onium ion concentration in the treatment solution after filtration was measured in the same manner as in the "Evaluation of the residual rate of onium ions after filtration" section above. The ruthenium concentration in the treatment solution after filtration was also measured using an ICP-OES (iCAP6500 DUO, manufactured by Thermo Fisher Scientific).

[0092] Comparative Example 4 A filtered treated solution was prepared in the same manner as in Example 19, except that no metal recovery agent was added to the treated solution. The ruthenium concentration in the filtered treated solution was measured using ICP-OES (iCAP6500 DUO, manufactured by Thermo Fisher Scientific).

[0093]

[0094] When the metal recovery agents described in Examples 19 and 20 were used, metallic ruthenium could be recovered by filter filtration. Furthermore, by using a metal recovery agent with a high surface tension, a good onium salt residual rate after filtration was obtained, demonstrating that the agent can be reused as a metal recovery agent. On the other hand, in Comparative Example 4, in which no metal recovery agent was added, it was confirmed that 100% of ruthenium metal remained in the treated solution after filter filtration.

[0095] 1 Filter 1 2 Filter 2 3 Filter 3 4 Pump 1 5 Pump 2 6 Chemical cabinet 7 Chemical liquid replenishment unit 8 Etching table 9 Valve 1 10 Valve 2

Claims

1. A filtration lubricant containing onium ions, wherein the surface tension at 25°C is 60 mN / m or more and 75 mN / m or less, and further contains 0.001 mol / L or more and 0.20 mol / L or less of hypohalite ions.

2. A filtration lubricant containing onium ions, wherein the surface tension at 25°C is 60 mN / m or more and 75 mN / m or less, and further contains periodate ions at a concentration of 0.001 mol / L or more and 0.20 mol / L or less.

3. The filtration lubricant according to claim 1 or 2, wherein the onium ion is one or more selected from the group consisting of onium ions represented by formulas (1) to (6). 【Chemistry 1】 【Chemistry 2】 【Transformation 3】 【Chemistry 4】 【Transformation 5】 【Transformation 6】 (In formulas (1) to (6), R １ , R ２ , R ３ , R ４ , R ５ , R ６ These are independently a C2-C9 alkyl group, an allyl group, an aralkyl group having a C1-C9 alkyl group, or an aryl group. Furthermore, the aryl group in the aralkyl group and at least one hydrogen in the ring of the aryl group may be replaced with fluorine, chlorine, a C1-C9 alkyl group, a C2-C9 alkenyl group, a C1-C9 alkoxy group, or a C2-C9 alkenyloxy group, and in these groups, at least one hydrogen may be replaced with fluorine, chlorine, bromine, or iodine. A is either an ammonium ion or a phosphonium ion. Z is an aromatic group or alicyclic group which may contain nitrogen, sulfur, or oxygen atoms, and in the aromatic group or alicyclic group, carbon or nitrogen may have an aromatic group which may be substituted with chlorine, bromine, fluorine, iodine, at least one C1-C9 alkyl group, at least one C2-C9 alkenyloxy group, at least one C1-C9 alkyl group, or an alicyclic group which may be substituted with at least one C1-C9 alkyl group. 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 with at least one alkyl group having 1 to 9 carbon atoms, or an alicyclic group which may be substituted with at least one alkyl group having 1 to 9 carbon atoms. n is an integer of 1 or 2 and indicates the number of R groups. When n is 2, R may be the same or different, and may form a ring. (a is an integer between 1 and 10.)

4. The filtration lubricant according to claim 1 or 2, wherein the concentration of the onium ion is 1 ppm by mass or more and 10,000 ppm by mass or less.

5. The filtration lubricant according to claim 1 or 2, wherein the filtration lubricant is used for processing a semiconductor wafer, and the semiconductor wafer contains at least one metal selected from Ru, Rh, Ti, Ta, Co, Cr, Hf, Os, Pt, Ni, Mn, Cu, Zr, La, Mo, and W.

6. The filtration lubricant according to claim 1 or 2, wherein the semiconductor wafer contains Ru.

7. A method for etching a semiconductor wafer, comprising the step of bringing a filtration lubricant according to claim 1 or 2 into contact with a semiconductor wafer.

8. A method for manufacturing a semiconductor device, comprising the steps of filtering a filtration lubricant according to claim 1 or 2, and subjecting the filtered filtration lubricant to etching a semiconductor wafer.

9. A method for manufacturing a semiconductor device according to claim 8, comprising a step of filtering the aforementioned filtration lubricant multiple times.

10. A method for regenerating used semiconductor processing solution, comprising the step of adding the filtration lubricant described in claim 1 or 2 to the used semiconductor processing solution.

11. A polishing composition comprising one or more onium ions selected from the group consisting of the onium ions represented by the following formulas (1) to (6), and a hypohalite ion. 【Transformation 7】 【Transformation 8】 【Chemistry 9】 【Chemistry 10】 【Chemistry 11】 【Chemistry 12】 (In formulas (1) to (6), R １ , R ２ , R ３ , R ４ , R ５ , R ６ are independently an alkyl group having 2 to 9 carbon atoms, an allyl group, an aralkyl group having an alkyl group having 1 to 9 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 with 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 with fluorine, chlorine, bromine, or iodine. A is either an ammonium ion or a phosphonium ion. Z is an aromatic group or alicyclic group which may contain nitrogen, sulfur, or oxygen atoms, and in the aromatic group or alicyclic group, carbon or nitrogen may have an aromatic group which may be substituted with chlorine, bromine, fluorine, iodine, at least one C1-C9 alkyl group, at least one C2-C9 alkenyloxy group, at least one C1-C9 alkyl group, or an alicyclic group which may be substituted with at least one C1-C9 alkyl group. 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 with at least one alkyl group having 1 to 9 carbon atoms, or an alicyclic group which may be substituted with at least one alkyl group having 1 to 9 carbon atoms. n is an integer of 1 or 2 and indicates the number of R groups. When n is 2, R may be the same or different, and may form a ring. (a is an integer between 1 and 10.)

12. A polishing composition comprising the filtration lubricant described in claim 1 or 2.

13. A method for polishing a semiconductor wafer using the polishing composition described in claim 11, in which a polishing composition is supplied to a polishing pad containing abrasive particles or a polishing pad not containing abrasive particles, and the surface of a semiconductor wafer to be polished is brought into contact with the polishing pad, and the wafer is polished by relative motion between the two.

14. A metal recovery agent containing an onium ion that coordinates to a metal oxide ion or a metal hydroxide ion.

15. The metal recovery agent according to claim 14, wherein the onium ion is one or more selected from phosphonium ions and ammonium ions.

16. A method for recovering metal from a spent semiconductor processing solution, comprising the step of adding the metal recovery agent described in claim 14 or 15 to the spent semiconductor processing solution.

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