pH / oxidation-reduction potential adjusted water manufacturing device and pH / oxidation-reduction potential adjusted water manufacturing method

Abstract

To provide an apparatus and method for producing pH and oxidation-reduction potential adjustment water capable of dissolving a predetermined amount of wiring metal and is used in manufacturing semiconductor wiring where cobalt is used as the wiring metal.SOLUTION: A pH and oxidation-reduction potential adjustment water producing system 1 has a platinum group metal-supported resin column 3 in an ultrapure water W supply line 2, and the ultrapure water supply line 2 then branches into a first adjustment water production line 4 and a second adjustment water production line 5. The first adjustment water production line 4 is connected to a pH adjuster tank 41 and an oxidation-reduction potential adjuster tank 42, and a first storage tank 43 is provided at the rear of the tank. The second adjustment water production line 5 has a pH adjuster tank 51 connected thereto and an oxidation-reduction potential adjuster tank 52 connected thereto, and a second storage tank 53 is provided at the rear of the tank.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an apparatus and method for producing pH / oxidation-reduction potential adjusted water used in the electronics industry and the like, and in particular to an apparatus and method for producing pH / oxidation-reduction potential adjusted water used in the manufacture of semiconductor wiring using cobalt as the wiring metal, which is capable of dissolving only a predetermined amount of wiring metal. [Background technology]

[0002] With the miniaturization of semiconductors in recent years, the width of wiring has also been shrinking. In the wiring manufacturing process of conventional semiconductor manufacturing, misalignment of wiring caused by manufacturing equipment occurred, but because the wiring width was wide, the impact of misalignment of wiring was negligible and did not affect yield. However, as the wiring width has become smaller, this misalignment of wiring, even if very slight, can affect yield and is no longer negligible. Since the miniaturization of wiring will continue in the future and misalignment of wiring is caused by manufacturing equipment, it is difficult to prevent the occurrence of misalignment of wiring itself.

[0003] Therefore, as a method to prevent the deterioration of semiconductor performance due to misalignment of wiring, development is underway on ultra-micro etching technology for wiring layers. This micro-etching technology involves dissolving the wiring layer to an extremely small extent in advance, using the interlayer insulating film between the wiring as a dike, creating a structure that prevents the wiring from touching each other even if the wiring is misaligned, thereby preventing short circuits. This technology will be necessary as miniaturization continues.

[0004] In this semiconductor manufacturing process, cobalt is sometimes used as the wiring metal, and wet processing is used to perform extremely minute etching of this wiring.For example, a commonly used technique is called digital etch, in which the metal is alternately treated with two liquids: APM (a mixed solution of ammonia water and hydrogen peroxide) and carbonated water, repeatedly oxidizing and dissolving the metal surface to gradually remove the wiring metal. Summary of the Invention [Problem to be solved by the invention]

[0005] However, with conventional micro-etching techniques such as digital etching, the amount of metal dissolved (i.e., depth, hereafter referred to as metal loss) varies depending on the wiring width (hereafter referred to as pattern loading), which can have a negative impact on semiconductor performance even if micro-etching is possible. Another problem is that the increased surface roughness of the wiring metal after micro-etching can degrade the electrical characteristics of the semiconductor. Specifically, digital etching using extremely dilute APM (e.g., ammonia concentration: 10 ppm, hydrogen peroxide concentration: 100 ppm) and carbonated water requires approximately 20 minutes of processing time to achieve a metal loss of 10 nm, and pattern loading occurs.

[0006] For this reason, there was a demand for an ultra-fine etching solution that would produce a constant metal loss regardless of the wiring width in the cobalt wiring manufacturing process and that could achieve a metal loss of 10 nm in a short processing time.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an apparatus and method for producing pH / oxidation-reduction potential adjusted water that can be used in the manufacture of semiconductor wiring using cobalt as the wiring metal and is capable of dissolving a predetermined amount of wiring metal. [Means for solving the problem]

[0008] In view of the above object, firstly, the present invention provides an apparatus for producing pH / oxidation-reduction potential adjusted water by adding a pH adjuster and an oxidation-reduction potential adjuster to ultrapure water to produce cleaning water of a desired pH and oxidation-reduction potential, the pH / oxidation-reduction potential adjusted water being used in the manufacture of semiconductor wiring using cobalt as the wiring metal, the apparatus comprising an ultrapure water supply line having a hydrogen peroxide removal mechanism, branch flow paths branched into two or more downstream of the hydrogen peroxide removal mechanism, a pH adjustment mechanism for adding a pH adjuster and an oxidation-reduction potential adjustment mechanism for adding an oxidation-reduction potential adjuster, each of the branch flow paths being provided with an adjusted water quality monitoring mechanism downstream of the pH adjustment mechanism and the oxidation-reduction potential adjustment mechanism, and an adjusted water quality monitoring mechanism for measuring the water quality of the pH / oxidation-reduction potential adjusted water, the amount of pH adjuster added from the pH adjustment mechanism and the oxidation-reduction potential adjustment mechanism being monitored based on the measurement results of the adjusted water quality monitoring mechanism. and a storage tank for storing pH / redox potential adjusted water provided in each of the branch flow paths, wherein at least one of the two or more types of pH / redox potential adjusted water has a pH of 9 or more and 13 or less when the pH adjuster is ammonia, and a redox potential of 0 V or more and 1.7 V or less when the redox potential adjuster is hydrogen peroxide, and at least another of the two or more types of pH / redox potential adjusted water has a pH of 0 or more and 3.5 or less when the pH adjuster is one or more selected from the group consisting of citric acid, formic acid, and carbon dioxide gas (Invention 1).

[0009] According to this invention (Invention 1), ultrapure water from an ultrapure water supply line is passed through a hydrogen peroxide removal mechanism to remove trace amounts of hydrogen peroxide contained in the ultrapure water, and the hydrogen peroxide-removed ultrapure water is supplied to two or more branched flow paths. A pH adjuster and an oxidation-reduction potential adjuster are added to each branched flow path to achieve the desired pH and oxidation-reduction potential, preparing two or more types of pH / oxidation-reduction potential adjusted water. The amounts of pH adjuster and oxidation-reduction potential adjuster added are then controlled by an addition amount control mechanism to achieve the desired pH and oxidation-reduction potential based on the measurement results of the adjusted water quality monitoring mechanism. This eliminates the influence of dissolved hydrogen peroxide in the raw water and produces two or more types of pH / oxidation-reduction potential adjusted water with different pHs and oxidation-reduction potentials. This allows cleaning to be performed using two or more types of pH / oxidation-reduction potential adjusted water with different pHs and oxidation-reduction potentials, making it possible to dissolve a predetermined amount of wiring metal in the semiconductor wiring manufacturing process using cobalt as the wiring metal.

[0010] In the above invention (Invention 1), the pH adjuster is one selected from the group consisting of ammonia, citric acid, and formic acid, and is preferably added to the ultrapure water supply line by a pressurizing means using a pump or a sealed tank and an inert gas (Invention 2).Furthermore, in the above invention (Invention 1), the pH adjuster is preferably carbon dioxide gas, and is added by gas dissolution using a gas-permeable membrane module or a direct gas-liquid contact device with an ejector (Invention 3).

[0011] According to such inventions (Inventions 2 and 3), the amounts of the pH adjuster and the oxidation-reduction potential adjuster added can be easily and precisely controlled.

[0012] In the above inventions (Inventions 1 to 3), it is preferable that the storage tank for the pH / oxidation-reduction potential adjusted water has a mechanism for supplying an inert gas (Invention 4).

[0013] According to this invention (Invention 4), it is possible to prevent oxygen and carbon dioxide from dissolving while storing the adjusted pH and oxidation-reduction potential, thereby preventing an increase in the dissolved oxygen concentration and suppressing fluctuations in pH and other parameters.

[0014] Secondly, the present invention provides a method for producing pH / oxidation-reduction potential adjusted water by adding a pH adjuster and an oxidation-reduction potential adjuster to ultrapure water to produce cleaning water having a desired pH and oxidation-reduction potential, the pH / oxidation-reduction potential adjusted water being used in the manufacture of semiconductor wiring using cobalt as the wiring metal, the method comprising the steps of: removing hydrogen peroxide from the ultrapure water by a hydrogen peroxide removal mechanism provided in an ultrapure water supply line; branching the ultrapure water from which the hydrogen peroxide has been removed into two or more branch flow paths; adjusting the pH of the ultrapure water from which the hydrogen peroxide has been removed by a pH adjustment mechanism; adjusting the oxidation-reduction potential of the ultrapure water from which the hydrogen peroxide has been removed by an oxidation-reduction potential adjustment mechanism; measuring the quality of the pH / oxidation-reduction potential adjusted water from which the pH and oxidation-reduction potential have been adjusted by an adjusted water quality monitoring mechanism; and monitoring the p from the pH adjustment mechanism based on the measurement results of the adjusted water quality monitoring mechanism. and a step of storing the pH / oxidation-reduction potential adjusted water in reservoirs provided in the two or more branched flow paths, wherein two or more types of pH / oxidation-reduction potential adjusted water can be supplied from the two or more branched flow paths, and at least one of the two or more types of pH / oxidation-reduction potential adjusted water has a pH of 9 or more and 13 or less when the pH adjuster is ammonia, and a redox potential of 0 V or more and 1.7 V or less when the redox potential adjuster is hydrogen peroxide, and at least another of the two or more types of pH / oxidation-reduction potential adjusted water has a pH of 0 or more and 3.5 or less when the pH adjuster is one or more selected from the group consisting of citric acid, formic acid, and carbon dioxide gas (Invention 5).

[0015] According to this invention (Invention 5), ultrapure water from an ultrapure water supply line is passed through a hydrogen peroxide removal mechanism to remove trace amounts of hydrogen peroxide contained in the ultrapure water, and the hydrogen peroxide-removed ultrapure water is supplied to two or more branched flow paths. A pH adjuster and an oxidation-reduction potential adjuster are added to each branched flow path to achieve the desired pH and oxidation-reduction potential, preparing two or more types of pH / oxidation-reduction potential adjusted water. The amounts of pH adjuster and oxidation-reduction potential adjuster added are then controlled by an addition amount control mechanism to achieve the desired pH and oxidation-reduction potential based on the measurement results of the adjusted water quality monitoring mechanism. This eliminates the influence of dissolved hydrogen peroxide in the raw water and produces two or more types of pH / oxidation-reduction potential adjusted water with different pHs and oxidation-reduction potentials. This allows cleaning to be performed using two or more types of pH / oxidation-reduction potential adjusted water with different pHs and oxidation-reduction potentials, making it possible to dissolve a predetermined amount of wiring metal in the semiconductor wiring manufacturing process using cobalt as the wiring metal.

[0016] In the above invention (Invention 5), the pH adjuster is one selected from the group consisting of ammonia, citric acid, and formic acid, and is preferably injected into the ultrapure water supply line by a pressurizing means using a pump or a sealed tank and an inert gas (Invention 6).Furthermore, in the above invention (Invention 5), the pH adjuster is preferably carbon dioxide gas, and is added by gas dissolution using a gas-permeable membrane module or a direct gas-liquid contact device with an ejector (Invention 7).

[0017] According to such inventions (Inventions 6 and 7), the amounts of the pH adjuster and the oxidation-reduction potential adjuster to be added can be easily and precisely controlled.

[0018] In the above inventions (Inventions 5 to 7), it is preferable that the storage tank for the pH / oxidation-reduction potential adjusted water is purged with an inert gas (Invention 8).

[0019] According to this invention (Invention 8), it is possible to prevent oxygen and carbon dioxide from dissolving while storing the adjusted pH and oxidation-reduction potential, thereby preventing an increase in the dissolved oxygen concentration and suppressing fluctuations in pH and other parameters. [Effects of the Invention]

[0020] The pH / oxidation-reduction potential adjusted water production device and production method of the present invention can produce two or more types of pH / oxidation-reduction potential adjusted water with different pHs and oxidation-reduction potentials. By combining these different pH / oxidation-reduction potential adjusted waters, it becomes possible to alternately wash with cleaning water with a pH and oxidation-reduction potential that suppresses cobalt dissolution and cleaning water with a different pH and oxidation-reduction potential that allows fine adjustment of cobalt dissolution by pH or oxidation-reduction potential. This makes it possible to dissolve only a specified amount of wiring metal in the semiconductor wiring manufacturing process that uses cobalt as the wiring metal. This enables ultra-fine etching with a constant metal loss, for example, of 10 nm, in a short processing time, regardless of differences in wiring width. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic diagram showing an apparatus for producing conditioned water according to a first embodiment of the present invention. [Figure 2] FIG. 4 is a schematic diagram showing a regulated water producing apparatus according to a second embodiment of the present invention. [Figure 3] FIG. 10 is a schematic diagram showing a regulated water producing apparatus according to a third embodiment of the present invention. [Figure 4] FIG. 10 is a schematic diagram showing an apparatus for producing conditioned water according to a fourth embodiment of the present invention. [Figure 5] 1 is a graph showing the relationship between wiring width and cobalt metal loss in Examples 1 to 3. [Figure 6] 10 is a graph showing the relationship between wiring width and cobalt metal loss in Examples 4 to 6. [Figure 7] 10 is a graph showing the relationship between wiring width and cobalt metal loss in Examples 7 to 9.

Best Mode for Carrying Out the Invention

[0022] Hereinafter, the manufacturing apparatus and manufacturing method of the pH·redox potential-adjusted water of the present invention will be described in detail based on each embodiment with reference to the accompanying drawings.

[0023] 〔First Embodiment〕 <Manufacturing Apparatus for pH·Redox Potential-Adjusted Water> FIG. 1 shows a pH·redox potential-adjusted water manufacturing apparatus according to the first embodiment of the present invention. In FIG. 1, the pH·redox potential-adjusted water manufacturing apparatus 1 is provided with a platinum group metal-supported resin column 3 as a hydrogen peroxide removal mechanism in the supply line 2 of ultrapure water W. The ultrapure water supply line 2 branches into a first adjusted water manufacturing line 4 and a second adjusted water manufacturing line 5 after this platinum group metal-supported resin column 3.

[0024] In this first adjusted water manufacturing line 4, a pH adjustant injection line 41A provided with a liquid supply mechanism 41B communicating with a pH adjustant tank 41 and a redox potential adjustant injection line 42A provided with a liquid supply mechanism 42B communicating with a redox potential adjustant tank 42 merge. A first storage tank 43 for storing the first pH·redox potential-adjusted water is provided at the subsequent stage of this redox potential adjustant injection line 42A. This first storage tank 43 is purged with an inert gas IG in this embodiment. And the first adjusted water manufacturing line 4 extends from this first storage tank 43 to the use point UP. Note that 44 is an on-off valve of the first adjusted water manufacturing line 4 toward the use point UP.

[0025] The second adjusted water production line 5 is joined by a pH adjuster injection line 51A equipped with a liquid supply mechanism 51B connected to a pH adjuster tank 51, and an oxidation-reduction potential adjuster injection line 52A equipped with a liquid supply mechanism 52B connected to an oxidation-reduction potential adjuster tank 52. A second storage tank 53 for storing the second pH / oxidation-reduction potential adjusted water is provided downstream of the oxidation-reduction potential adjuster injection line 52A, and in this embodiment, this second storage tank 53 is purged with an inert gas IG. The second adjusted water production line 5 extends from this second storage tank 53 to the point of use UP. Reference numeral 54 denotes an on-off valve of the second adjusted water production line 5 leading to the point of use UP, 55 denotes a bypass line connecting the first adjusted water production line 4 and the second adjusted water production line 5, and 56 denotes an on-off valve of the bypass line.

[0026] In this embodiment, downstream of the pH adjuster injection line 41A and the oxidation-reduction potential adjuster injection line 42A of the first adjusted water production line 4, for example, in the storage tank 43, and downstream of the pH adjuster injection line 51A and the oxidation-reduction potential adjuster injection line 52A of the second adjusted water production line 5, for example, in the storage tank 53, are provided adjusted water quality monitoring mechanisms, such as a pH meter as a pH measuring means and an ORP meter as an oxidation-reduction potential measuring means, not shown, and these pH meter and ORP meter are connected to a control device such as a personal computer. This control device can control the amount of pH adjuster and the amount of oxidation-reduction potential adjuster injected based on the measurements of the pH meter and the ORP meter.

[0027] <Ultra pure water> In this embodiment, the ultrapure water W serving as raw water preferably has, for example, a resistivity of 18.1 MΩ·cm or more, fine particles of 50 nm or more in diameter and 1000 particles / L or less, viable bacteria of 1 particle / L or less, TOC (Total Organic Carbon) of 1 μg / L or less, total silicon of 0.1 μg / L or less, metals of 1 ng / L or less, ions of 10 ng / L or less, hydrogen peroxide of 30 μg / L or less, and a water temperature of 25±2°C.

[0028] <Hydrogen peroxide removal mechanism> In this embodiment, a platinum group metal-supported resin column 3 is used as the hydrogen peroxide removal mechanism.

[0029] (Platinum group metal) In this embodiment, examples of the platinum group metal supported on the platinum group metal-supported resin used in the platinum group metal-supported resin column 3 include ruthenium, rhodium, palladium, osmium, iridium, and platinum. These platinum group metals can be used alone, in combination of two or more, as an alloy of two or more, or as a purified product of a naturally occurring mixture without being separated into individual components. Among these, platinum, palladium, platinum / palladium alloy alone or a mixture of two or more of these can be preferably used because of their strong catalytic activity. Also, nanoparticles of these metals can be particularly preferably used.

[0030] (Carrier resin) In the platinum group metal-supported resin column 3, an ion exchange resin can be used as the carrier resin for supporting the platinum group metal. Among these, an anion exchange resin can be particularly preferably used. Since platinum-based metals are negatively charged, they are stably supported on the anion exchange resin and are difficult to peel off. The exchange group of the anion exchange resin is preferably in the OH form. The OH-form anion exchange resin makes the resin surface alkaline and promotes the decomposition of hydrogen peroxide.

[0031] <pH adjuster injection device> In this embodiment, there is no particular limitation on the pH adjuster injection device, and a general drug injection device can be used. The pH adjuster tanks 41 and 51 may have an inert gas supply mechanism. When the pH adjuster is a liquid, a pump such as a diaphragm pump can be used, and it is desirable to provide a mechanism for purging the inside of the pH adjuster tanks 41 and 51 with an inert gas or removing dissolved oxygen in the pH adjuster liquid in the tank using a degassing membrane. In addition, a pressure-type pump in which a pH adjuster or a redox potential adjuster is placed in a sealed container together with an inert gas such as N2 gas and these agents are extruded by the pressure of the inert gas can also be preferably used. When the pH adjuster is a gas, a direct gas-liquid contact device such as a gas permeable membrane module or an ejector can be used.

[0032] <pH adjuster> In this embodiment, there is no particular limitation on the pH adjuster injected from the pH adjuster tanks 41 and 51. When adjusting to a pH less than 7, liquids such as citric acid, formic acid, hydrochloric acid, or gases such as carbon dioxide gas (CO2) can be used. When adjusting to a pH of 7 or more, ammonia, sodium hydroxide, potassium hydroxide, TMAH, or the like can be used. When using the pH / redox potential-adjusted water as the cleaning water for the wafer with exposed cobalt, it is preferable to make it alkaline. However, an alkali metal solution such as sodium hydroxide is not suitable because it contains metal components. Therefore, in this embodiment, it is most preferable to use ammonia, citric acid, or the like. When the pH adjuster is one selected from the group consisting of ammonia, citric acid, and formic acid, it is desirable to inject the drug into the ultrapure water supply line by means of a pump or a pressurizing means using a sealed tank and an inert gas. When the pH adjuster is carbon dioxide gas, it is desirable to add it by gas dissolution using a direct gas-liquid contact device such as a gas permeable membrane module or an ejector.

[0033] <Redox potential adjuster injection device> In this embodiment, there are no particular restrictions on the redox potential regulator injection device, and a general drug injection device can be used. The redox potential regulator tanks 42 and 52 may have an inert gas supply mechanism. When the redox potential regulator is a liquid, a pump such as a diaphragm pump can be used, and it is desirable to provide a mechanism for purging the inside of the redox potential regulator tanks 42 and 52 with an inert gas or removing dissolved oxygen in the pH regulator liquid in the tank using a degassing membrane. Also, a pressure-type pump that places the redox potential regulator in a sealed container together with an inert gas such as N2 gas and extrudes these agents by the pressure of the inert gas can also be preferably used. When the redox potential regulator is a gas, a direct gas-liquid contact device such as a gas permeable membrane module or an ejector can be used.

[0034] <Redox potential regulator> In this embodiment, there are no particular restrictions on the redox potential regulator injected from the redox potential regulator tanks 42 and 52. However, to adjust the redox potential to the positive side, a liquid such as hydrogen peroxide water or a gas such as ozone gas or oxygen gas can be used. To adjust the redox potential to the negative side, a liquid such as oxalic acid or a gas such as hydrogen can be used. For example, when used as the washing water for a wafer with exposed cobalt, it is preferable to use hydrogen peroxide water because it is preferable to adjust the redox potential to positive in order to suppress the elution of cobalt.

[0035] <Method for producing pH·redox potential adjusted water> The method for producing pH·redox potential adjusted water using the pH·redox potential adjusted water production apparatus 1 of this embodiment having the configuration as described above will be described below.

[0036] (First method for producing pH·redox potential adjusted water) Because raw ultrapure water W generally contains hydrogen peroxide at the level of several tens of ppb, it is necessary to remove the hydrogen peroxide from the ultrapure water W beforehand in order to accurately control the oxidation-reduction potential of the cleaning solution. Therefore, the ultrapure water W is first supplied from a supply line 2 to a platinum group metal-loaded resin column 3. In this platinum group metal-loaded resin column 3, the catalytic action of the platinum group metal decomposes and removes the hydrogen peroxide in the ultrapure water W, i.e., it functions as a hydrogen peroxide removal mechanism. The ultrapure water W then branches into a first adjusted water production line 4 and a second adjusted water production line 5.

[0037] Then, in the first adjusted water production line 4, a pH adjuster is injected from a pH adjuster tank 41. The amount of pH adjuster added can be set appropriately depending on the desired pH, the flow rate of the first adjusted water production line 4, and the concentration of the pH adjuster. For example, when an alkaline solution is to be added for cleaning a semiconductor having fine cobalt lines, an amount of pH adjuster that brings the cleaning solution to a pH range of 9 to 13 should be added. When an acidic solution is to be added, an amount of pH adjuster that brings the cleaning solution to a pH range of 0 to 3.5 should be added.

[0038] Next, an oxidation-reduction potential adjuster is poured from the oxidation-reduction potential adjuster tank 42. The amount of oxidation-reduction potential adjuster added can be set appropriately depending on the desired oxidation-reduction potential, the flow rate of the first adjusted water production line 4, and the concentration of the oxidation-reduction potential adjuster. For example, when cleaning a semiconductor having fine cobalt lines, an amount that brings the oxidation-reduction potential of the cleaning solution into the range of 0 to 1.7 V should be added.

[0039] When the pH adjuster is ammonia, the first pH / oxidation-reduction potential adjusted water W1 preferably has a pH of 9 or more and 13 or less, and when the oxidation-reduction potential adjuster is hydrogen peroxide, the oxidation-reduction potential of the first pH / oxidation-reduction potential adjusted water W1 preferably has a pH of 0 or more and 3.5 or less, when the pH adjuster is one or more selected from the group consisting of citric acid, formic acid, and carbon dioxide gas.

[0040] Once the first pH / oxidation-reduction potential adjusted water W1 is produced in this manner, it is stored in the first storage tank 43. This first storage tank 43 is purged with an inert gas, which prevents oxygen or carbon dioxide from dissolving in the first pH / oxidation-reduction potential adjusted water W1 and causing fluctuations in the pH or oxidation-reduction potential while the first pH / oxidation-reduction potential adjusted water W1 is being stored. At this time, the amount of pH adjuster added from the pH adjuster tank 41 and the amount of oxidation-reduction potential adjuster added from the oxidation-reduction potential adjuster tank 42 are controlled by a control device based on the measurement results of a pH meter and an ORP meter (not shown), thereby enabling a stable supply of the first pH / oxidation-reduction potential adjusted water W1 having the desired pH and oxidation-reduction potential.

[0041] (Second method for producing pH / oxidation-reduction potential adjusted water) Meanwhile, second pH / oxidation-reduction potential adjusted water W2 can be produced from the ultrapure water branched off to the second adjusted water production line 5 by injecting a pH adjuster from the pH adjuster tank 51 in the same manner as for the first pH / oxidation-reduction potential adjusted water W1, and further injecting an oxidation-reduction potential adjuster from the oxidation-reduction potential adjuster tank 52. At this time, the amount of pH adjuster added from the pH adjuster tank 51 and the amount of oxidation-reduction potential adjuster added from the oxidation-reduction potential adjuster tank 52 are controlled by a control device based on the measurement results of a pH meter and an ORP meter (not shown), thereby enabling a stable supply of second pH / oxidation-reduction potential adjusted water W2 with the desired pH and oxidation-reduction potential.

[0042] When the pH adjuster is ammonia, the second pH / oxidation-reduction potential adjusted water W2 preferably has a pH of 9 to 13, and when the pH adjuster is hydrogen peroxide, the oxidation-reduction potential of the second pH / oxidation-reduction potential adjusted water W2 preferably has a pH of 0 to 3.5, when the pH adjuster is one or more selected from the group consisting of citric acid, formic acid, and carbon dioxide gas.

[0043] The first pH / oxidation-reduction potential adjusted water W1 preferably has a pH of 9 to 13 when the pH adjuster is ammonia, and a redox potential of 0 to 1.7 V when the redox potential adjuster is hydrogen peroxide. In this case, the second pH / oxidation-reduction potential adjusted water W2 preferably has a pH of 0 to 3.5 when the pH adjuster is one or more selected from the group consisting of citric acid, formic acid, and carbon dioxide. Furthermore, the first pH / oxidation-reduction potential adjusted water W1 preferably has a pH of 0 to 3.5 when the pH adjuster is one or more selected from the group consisting of citric acid, formic acid, and carbon dioxide. In this case, the second pH / oxidation-reduction potential adjusted water W2 preferably has a pH of 9 to 13 when the pH adjuster is ammonia, and a redox potential of 0 to 1.7 V when the redox potential adjuster is hydrogen peroxide.

[0044] The first pH / oxidation-reduction potential adjusted water W1 and the second pH / oxidation-reduction potential adjusted water W2 thus produced are sent to the point of use UP, but in this embodiment, the two waters have different qualities. In the second adjusted water production line 5, addition from either the pH adjuster tank 51 or the oxidation-reduction potential adjuster tank 52 may be omitted. Furthermore, by opening the bypass line 5 as needed, the two waters can be mixed and used.

[0045] (Example of supplying pH / oxidation-reduction potential adjusted water) Hereinafter, the manufacturing method of the first pH / oxidation-reduction potential adjusted water W1 and the second pH / oxidation-reduction potential adjusted water W2 as described above will be described using an example of performing micro-etching treatment on wiring made of cobalt.

[0046] A technique called digital etching is used for micro-etching of cobalt wiring. This is a method that dissolves the metal in stages by repeatedly oxidizing the metal surface and dissolving the oxide film. When micro-etching cobalt using digital etching, the first step is to form an oxide film on the cobalt surface without dissolving the cobalt, and the second step is to dissolve only the metal oxide film formed in the first step without dissolving the cobalt.

[0047] According to the Pourbaix diagram, which shows the most stable chemical species of metals in aqueous solutions under certain potential-pH conditions, cobalt becomes passive and difficult to dissolve under alkaline conditions, particularly in the pH range of 9 to 13. The addition of 10 to 100 ppm of hydrogen peroxide to alkaline solutions with a pH of 9 to 13 minimizes the cobalt dissolution rate. However, at hydrogen peroxide concentrations of 1000 ppm or higher, the cobalt dissolution rate is known to be approximately 30 times faster than without hydrogen peroxide. Therefore, to oxidize the surface while preventing cobalt dissolution in the first step of digital etching, the pH and redox potential of the APM (ammonia water and hydrogen peroxide solution) must be more precisely controlled.

[0048] On the other hand, according to the Pourbaix diagram, under acidic conditions, the behavior of dissolution and passivation differs depending on the pH and redox potential of the aqueous solution. In order to microetch a specified amount of cobalt within a specified time, it is necessary to accelerate the removal rate of the cobalt oxide film in the second step, and to do so, the pH of the treatment solution must be kept below 5.

[0049] In view of these, in order to perform ultra-fine etching of a predetermined amount of cobalt within a predetermined time while suppressing the occurrence of pattern loading, the pH and redox potential at which cobalt dissolution is least likely to occur are adjusted so that the pH ranges from 9 to 13 and the redox potential ranges from 0 to 1.7 V (hydrogen peroxide is about 10 to 100 ppm). A first pH·redox potential adjustment water W1 composed of a mixed solution of aqueous ammonia and aqueous hydrogen peroxide is adjusted and supplied from the first adjustment water production line 4 to the use point UP to perform the cleaning in the first step. Thereby, an oxide film is formed on the cobalt surface without dissolving the cobalt. At this time, the on-off valve 54 of the second adjustment water production line 5 is closed.

[0050] Next, in order to perform ultra-fine etching of a predetermined amount of cobalt within a predetermined time, in order to accelerate the removal rate of the cobalt oxide film, citric acid, formic acid, etc. are added so that the pH of the treatment liquid is less than 5 to adjust the second pH·redox potential adjustment water W2. Then, the on-off valve 44 of the first adjustment water production line 4 is closed to stop the supply of the first pH·redox potential adjustment water W1, and the on-off valve 54 of the second adjustment water production line 5 is opened to supply the second pH·redox potential adjustment water W2 from the second adjustment water production line 5 to the use point UP to perform the cleaning in the second step. Thereby, a predetermined amount of cobalt is etched ultra-finely.

[0051] In this way, ultra-fine etching of the wiring of a semiconductor having wiring made of cobalt can be efficiently performed in a short time.

[0052] 〔Second Embodiment〕 <pH·Redox Potential Adjustment Water Production Apparatus> FIG. 2 shows a pH·redox potential adjustment water production apparatus according to the second embodiment of the present invention. The same components as those in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

[0053] In FIG. 2, the pH·oxidation-reduction potential-adjusted water production apparatus 1 includes a first degassing membrane apparatus 47 having a vacuum pump 47A downstream of the pH adjuster tank 41 of the first adjusted water production line 4. Instead of the oxidation-reduction potential adjuster tank 42, the oxidation-reduction potential adjuster injection line 42A, and the liquid supply mechanism 42B as the oxidation-reduction potential adjustment mechanism, in this embodiment, it has a first gas dissolution membrane apparatus 48 that dissolves ozone as the oxidation-reduction potential adjuster. Further, it includes a second degassing membrane apparatus 57 having a vacuum pump 57A downstream of the pH adjuster tank 51 of the second adjusted water production line 5. Instead of the oxidation-reduction potential adjuster tank 52, the oxidation-reduction potential adjuster injection line 52A, and the liquid supply mechanism 52B as the oxidation-reduction potential adjustment mechanism, it has a second gas dissolution membrane apparatus 58 that dissolves ozone.

[0054] <Method for producing pH·oxidation-reduction potential-adjusted water> A method for producing pH·oxidation-reduction potential-adjusted water using the pH·oxidation-reduction potential-adjusted water production apparatus of this embodiment having the configuration described above will be described below.

[0055] (Method for producing the first pH·oxidation-reduction potential-adjusted water) Since ultrapure water W as raw water generally contains hydrogen peroxide at a level of several tens of ppb, in order to accurately control the oxidation-reduction potential of the cleaning liquid, it is necessary to remove the hydrogen peroxide in the ultrapure water W in advance. Therefore, first, ultrapure water W is supplied from the supply line 2 to the platinum group metal-supported resin column 3. In this platinum group metal-supported resin column 3, the hydrogen peroxide in the ultrapure water W is decomposed and removed by the catalytic action of the platinum group metal, that is, it functions as a hydrogen peroxide removal mechanism. Thereafter, this ultrapure water W branches into a first adjusted water production line 4 and a second adjusted water production line 5.

[0056] Then, a pH adjuster is injected from the pH adjuster tank 41 into the first adjusted water production line 4. The amount of pH adjuster added can be set appropriately depending on the desired pH, the flow rate of the first adjusted water production line 4, and the concentration of the pH adjuster. For example, when cleaning a semiconductor having fine cobalt lines, if the cleaning solution is to be alkaline, an amount of pH adjuster added will bring the cleaning solution to a pH range of 9 to 13. If the cleaning solution is to be acidic, an amount of pH adjuster added will bring the cleaning solution to a pH range of 0 to 3.5.

[0057] Next, the ultrapure water W after the pH adjustment is degassed in the first degassing membrane device 47. This removes dissolved gases such as dissolved oxygen from the ultrapure water W. Then, ozone gas is dissolved in the first gas dissolution membrane device 48. At this time, since the ultrapure water W after the pH adjustment has been degassed, the ozone gas can be efficiently dissolved. This allows the oxidation-reduction potential of the ultrapure water W to be adjusted to a positive value.

[0058] Once the first pH / oxidation-reduction potential adjusted water W1 is produced in this manner, it is stored in the first storage tank 43. Since this first storage tank 43 is purged with an inert gas, it is possible to prevent oxygen or carbon dioxide from dissolving in the first pH / oxidation-reduction potential adjusted water W1 while the resulting pH / oxidation-reduction potential adjusted water is stored, which would cause the pH or oxidation-reduction potential to fluctuate.

[0059] (Second method for producing pH / oxidation-reduction potential adjusted water) On the other hand, the ultrapure water branched off to the second adjusted water production line 5 can be treated in the same manner as in the case of the first pH / oxidation-reduction potential adjusted water W1 by injecting a pH adjuster from the pH adjuster tank 51, degassing it in the second degassing membrane device 57, and then dissolving ozone gas in the second gas dissolution membrane device 58, thereby producing the second pH / oxidation-reduction potential adjusted water W2.

[0060] The combination of pH adjuster and redox potential adjuster to obtain the predetermined pH and redox potential in the first pH / redox potential adjusted water W1 and the second pH / redox potential adjusted water W2 is as described in the first embodiment.

[0061] 〔Third Embodiment〕 <pH and Redox Potential Adjusted Water Production Apparatus> FIG. 3 shows a pH and redox potential adjusted water production apparatus according to the third embodiment of the present invention. The same components as those in the above-described first embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0062] In FIG. 3, the pH and redox potential adjusted water production apparatus 1 supplies N2 gas, which is an inert gas, to the pH adjuster tank 41 and the redox potential adjuster tank 42 via the gas supply pipe 61 instead of the liquid supply mechanisms 41B and 42B in the first embodiment, thereby extruding the pH adjuster and the redox potential adjuster, and also supplying N2 gas as a purge gas to the first storage tank 43. Similarly, instead of the liquid supply mechanisms 51B and 52B, N2 gas, which is an inert gas, is supplied to the pH adjuster tank 51 and the redox potential adjuster tank 52 via the gas supply pipe 62, thereby extruding the pH adjuster and the redox potential adjuster, and also having a configuration of supplying N2 gas to the second storage tank 53.

[0063] <pH and Redox Potential Adjusted Water Production Method> The pH and redox potential adjusted water production apparatus using the pH and redox potential adjusted water production apparatus of the present embodiment having the above-described configuration can also produce the first pH and redox potential adjusted water W1 and the second pH and redox potential adjusted water W2 in the same manner as in the first embodiment. In particular, in the present embodiment, since the pH adjuster and the redox potential adjuster are extruded from each tank by N2 gas, minute control of the supply amounts of the pH adjuster and the redox potential adjuster is possible.

[0064] The combination of the pH adjuster and the redox potential adjuster for obtaining a predetermined pH and redox potential in the first pH and redox potential adjusted water W1 and the second pH and redox potential adjusted water W2 is as described in the first embodiment.

[0065] 〔Fourth Embodiment〕 <pH and Redox Potential Adjusted Water Production Apparatus> FIG. 4 shows a pH and redox potential adjusted water production apparatus according to a fourth embodiment of the present invention. The same components as those in the above-described first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

[0066] In FIG. 4, a pH and redox potential adjusted water production apparatus 1 includes a first degassing membrane apparatus 47 having a vacuum pump 47A in a first adjusted water production line 4. Instead of a pH adjuster tank 41, a pH adjuster injection line 41A, and a liquid supply mechanism 41B as a pH adjustment mechanism, in this embodiment, it has a first gas dissolution membrane apparatus 71 that dissolves CO2 as a pH adjuster. Further, a second degassing membrane apparatus 57 having a vacuum pump 57A is provided in a second adjusted water production line 5. Instead of a pH adjuster tank 51, a pH adjuster injection line 52A, and a liquid supply mechanism 52B as a pH adjustment mechanism, it has a second gas dissolution membrane apparatus 72 that dissolves CO2 as a pH adjuster.

[0067] <pH and Redox Potential Adjusted Water Production Method> A method for producing pH and redox potential adjusted water using the pH and redox potential adjusted water production apparatus of this embodiment having the above-described configuration will be described below.

[0068] (First Method for Producing pH and Redox Potential Adjusted Water) Since ultrapure water W as raw water generally contains hydrogen peroxide at a level of several tens of ppb, in order to accurately control the redox potential of the cleaning liquid, it is necessary to remove hydrogen peroxide in ultrapure water W in advance. Therefore, first, ultrapure water W is supplied from a supply line 2 to a platinum group metal-supported resin column 3. In this platinum group metal-supported resin column 3, hydrogen peroxide in ultrapure water W is decomposed and removed by the catalytic action of the platinum group metal, that is, it functions as a hydrogen peroxide removal mechanism. Thereafter, this ultrapure water W branches into a first adjusted water production line 4 and a second adjusted water production line 5.

[0069] Then, in the first adjusted water production line 4, the ultrapure water W is degassed in the first degassing membrane device 47. This removes dissolved gases such as dissolved oxygen from the ultrapure water W. Next, CO2 gas is dissolved in the first gas dissolution membrane device 71. At this time, since the ultrapure water W has been degassed, CO2 gas can be efficiently dissolved. This allows the ultrapure water W to be adjusted to be acidic.

[0070] Next, an oxidation-reduction potential adjuster is injected from the oxidation-reduction potential adjuster tank 42. The amount of oxidation-reduction potential adjuster added can be appropriately set depending on the desired oxidation-reduction potential, the flow rate of the first adjusted water production line 4, and the concentration of the oxidation-reduction potential adjuster. For example, when cleaning a semiconductor having fine cobalt lines, an amount that brings the oxidation-reduction potential of the cleaning solution into the range of 0 to 1.7 V should be added.

[0071] Once the first pH / oxidation-reduction potential adjusted water W1 is produced in this manner, it is stored in the first storage tank 43. Since this first storage tank 43 is purged with an inert gas, it is possible to prevent oxygen or carbon dioxide from dissolving in the first pH / oxidation-reduction potential adjusted water W1 while the resulting pH / oxidation-reduction potential adjusted water is stored, which would cause the pH or oxidation-reduction potential to fluctuate.

[0072] (Second method for producing pH / oxidation-reduction potential adjusted water) On the other hand, the ultrapure water branched off to the second adjusted water production line 5 can be degassed in a second degassing membrane device 57, as in the case of the first pH / oxidation-reduction potential adjusted water W1, and then CO2 gas is dissolved in a second gas dissolution membrane device 72, and then an oxidation-reduction potential adjuster is injected from the oxidation-reduction potential adjuster tank 52 to produce the second pH / oxidation-reduction potential adjusted water W2.

[0073] The combination of pH adjuster and redox potential adjuster to obtain the predetermined pH and redox potential in the first pH / redox potential adjusted water W1 and the second pH / redox potential adjusted water W2 is as described in the first embodiment.

[0074] The apparatus and method for producing pH / oxidation-reduction potential adjusted water of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the above-described embodiment and various modifications are possible. For example, in the third embodiment, the oxidation-reduction potential may be adjusted in the negative direction by dissolving hydrogen gas instead of ozone gas. Furthermore, the apparatus may be constructed by arbitrarily combining the configurations of the first adjusted water production line 4 and the second adjusted water production line 5 of the apparatus shown in Figures 1 to 4. Furthermore, a mechanism for removing dissolved oxygen from the adjusted first pH / oxidation-reduction potential adjusted water W1 and second pH / oxidation-reduction potential adjusted water W2 may be further provided.

[0075] In the above embodiment, the ultrapure water supply line 2 branches into two branch paths, the first adjusted water production line 4 and the second adjusted water production line 5, downstream of the platinum group metal-supported resin column 3. However, the ultrapure water supply line 2 may branch into two or more branch paths downstream of the platinum group metal-supported resin column 3. Each of the two or more branch paths may be provided with a pH adjustment mechanism and an oxidation-reduction potential adjustment mechanism, and two or more types of pH / oxidation-reduction potential adjusted water may be supplied from the two or more branch paths. In this case, at least one of the two or more types of pH / oxidation-reduction potential adjusted water may have a pH of 9 to 13 when the pH adjuster is ammonia and a oxidation-reduction potential of 0 V to 1.7 V when the oxidation-reduction potential adjuster is hydrogen peroxide. At least another of the two or more types of pH / oxidation-reduction potential adjusted water may have a pH of 0 to 3.5 when the pH adjuster is one or more selected from the group consisting of citric acid, formic acid, and carbon dioxide. [Example]

[0076] The present invention will be further illustrated by the following specific examples.

[0077] [Examples 1 and 2] (Preparation of Treatment Solution 1) Based on the apparatus shown in Figure 1, the second adjusted water production line 5 was equipped with a second degassing membrane device 57 having a vacuum pump 57A and a second gas dissolving membrane device 72 that dissolves CO2 gas, as shown in Figure 4, to form a pH / oxidation-reduction potential adjusted water production apparatus.

[0078] Using this equipment, in the first adjusted water production line 4, ammonia from the pH adjuster tank 41 and hydrogen peroxide solution from the oxidation-reduction potential adjuster tank 42 were added to ultrapure water W, and extremely diluted APM (ammonia concentration: 10 ppm (pH approximately 10), hydrogen peroxide concentration: 100 ppm (oxidation-reduction potential 0.05 V)) was produced as first pH / oxidation-reduction potential adjusted water W1. In addition, in the second adjusted water production line 5, CO2 gas was dissolved from the second gas dissolution membrane device 72 to produce carbonated water (carbon dioxide concentration: 20 ppm (pH approximately 5.5)) as second pH / oxidation-reduction potential adjusted water W2. These adjusted waters W1 and W2 were used as treated liquid 1.

[0079] (Digital Etch Processing Test) A CVD / ECD Co patterned wafer (wiring width: 50-500 nm, 300 mmΦ) was cut into a 30 mm x 30 mm piece to serve as a test piece. This test piece was immersed in the first pH / oxidation-reduction potential adjusted water W1 for 1 minute and the second pH / oxidation-reduction potential adjusted water W2 for 1 minute, and this cycle was repeated five times (Example 1) and ten times (Example 2). The wiring portion of the Co patterned wafer was then observed with an XSEM to measure the cobalt metal loss. The results are shown in Figure 5.

[0080] [Example 3] (Preparation of Treatment Solution 2) Using the apparatus shown in Figure 1, in the first adjusted water production line 4, ammonia from the pH adjuster tank 41 and hydrogen peroxide solution from the oxidation-reduction potential adjuster tank 42 were added to ultrapure water W, and extremely diluted APM (ammonia concentration: 10 ppm (pH approximately 10), hydrogen peroxide concentration: 100 ppm (oxidation-reduction potential 0.05 V)) was produced as first pH / oxidation-reduction potential adjusted water W1. In addition, in the second adjusted water production line 5, citric acid was added from the pH adjuster tank 41 to produce second pH / oxidation-reduction potential adjusted water W2, citric acid-dissolved water (citric acid concentration: 5 mM (pH 2.8)). These adjusted waters W1 and W2 were used as treated liquid 2.

[0081] (Digital Etch Processing Test) Using this treatment solution 2, the test piece was immersed in the first pH / oxidation-reduction potential adjusted water W1 for 1 minute and then in the second pH / oxidation-reduction potential adjusted water W2 for 1 minute, a cycle repeated five times (Example 3), as in Example 1. The wiring portion of the Co pattern wafer was then observed with an XSEM to measure the cobalt metal loss. The results are also shown in Figure 5.

[0082] As is clear from Figure 5, in Examples 1 and 2, in which treatment solution 1 was used in which second pH / oxidation-reduction potential adjusted water W2 was conventional carbonated water, the treatment times with first pH / oxidation-reduction potential adjusted water W1 and second pH / oxidation-reduction potential adjusted water W2 were each 1 minute. Therefore, in Example 1, the total treatment time was 10 minutes and the metal loss was approximately 12 nm / 10 minutes, while in Example 2, the total treatment time was 20 minutes and the metal loss was approximately 25 nm / 20 minutes. It can be seen that in Examples 1 and 2, it is difficult to achieve the cobalt metal loss of 10 nm / 5 minutes, which is generally required for ultra-fine etching. Furthermore, it can be seen that the cobalt metal loss differs depending on the wiring width, resulting in pattern loading.

[0083] In contrast, in Example 3, in which the second pH / oxidation-reduction potential adjusted water W2 was changed from carbonated water as in the prior art to 5 mM citric acid dissolved water, the cobalt metal loss when the digital etch process was repeated five times was approximately 25 nm / 10 minutes on average, and it can be inferred that a cobalt metal loss of 10 nm / 5 minutes can be achieved by changing the number of repetitions to two. Furthermore, it can be seen that there is almost no difference in cobalt metal loss due to differences in wiring width, and pattern loading does not occur.

[0084] [Examples 4 to 6] (Preparation of Treatment Solution 3) Using the apparatus shown in Figure 1, in the first adjusted water production line 4, ammonia from pH adjuster tank 41 and hydrogen peroxide solution from oxidation-reduction potential adjuster tank 42 were added to ultrapure water W to produce extremely diluted APM (ammonia concentration: 10 ppm, hydrogen peroxide concentration: 100 ppm) as first pH / oxidation-reduction potential adjusted water W1. In addition, in the second adjusted water production line 5, a predetermined amount of citric acid was added from pH adjuster tank 41 to produce second pH / oxidation-reduction potential adjusted water W2, i.e., citric acid-dissolved water (citric acid concentrations: 0.0005 mM: Example 4, 0.05 mM: Example 5, 5 mM (pH 2.8): Example 6). These adjusted waters W1 and W2 were used as treatment liquid 3.

[0085] (Digital Etch Processing Test) Using this treatment solution 3, the test piece was immersed in the first pH / oxidation-reduction potential adjusted water W1 for 1 minute and then in the second pH / oxidation-reduction potential adjusted water W2 for 1 minute, and this cycle was repeated five times in the same manner as in Example 1. The wiring portion of the Co pattern wafer was then observed with an XSEM to measure the cobalt metal loss. The results are shown in Figure 6.

[0086] As is clear from Figure 6, when the cobalt metal loss due to differences in citric acid concentration was examined using the second pH / oxidation-reduction potential adjusted water W2, the average metal loss was 9 nm / 10 min in Example 4, 10 nm / 10 min in Example 5, and 25 nm / 10 min in Example 6. Furthermore, while the cobalt metal loss varied depending on the line width in Examples 4 and 5, the cobalt metal loss in Example 6 showed almost no change with line width. From these results, it can be inferred that citric acid-dissolved water with a citric acid concentration of 5 mM or more is effective in achieving the cobalt metal loss of 10 nm / 5 min generally required for ultrafine etching without causing pattern loading.

[0087] [Examples 7 to 9] (Preparation of Treatment Solution 4) Using the apparatus shown in Figure 1, in the first adjusted water production line 4, ammonia from the pH adjuster tank 41 and hydrogen peroxide water from the oxidation-reduction potential adjuster tank 42 were added to ultrapure water W, and extremely diluted APM (ammonia concentration: 10 ppm, hydrogen peroxide concentration: 100 ppm) was produced as first pH / oxidation-reduction potential adjusted water W1. In addition, in the second adjusted water production line 5, a predetermined amount of citric acid was added from the pH adjuster tank 41 to produce second pH / oxidation-reduction potential adjusted water W2, citric acid-dissolved water (citric acid concentration 5 mM (pH 2.8): Example 7). These adjusted waters W1 and W2 were used as the treated liquid 4.

[0088] (Preparation of Treatment Solution 5) In the treatment liquid 4, the first pH / oxidation-reduction potential adjusted water W1 was the same, and in the second adjusted water production line 5, formic acid was added from the pH adjuster tank 41 to produce second pH / oxidation-reduction potential adjusted water W2, which was formic acid-dissolved water (formic acid concentration 0.05 mM (pH 4.4): Example 8). These adjusted waters W1 and W2 were used to produce treatment liquid 5.

[0089] (Preparation of Treatment Solution 6) In the treatment liquid 4, the first pH / oxidation-reduction potential adjusted water W1 was the same, and in the second adjusted water production line 5, formic acid was added from the pH adjuster tank 41 to produce second pH / oxidation-reduction potential adjusted water W2, which was formic acid-dissolved water (formic acid concentration 5 mM (pH 3.1): Example 9). These adjusted waters W1 and W2 were used to produce treatment liquid 6.

[0090] (Digital Etch Processing Test) Using these treatment solutions 4 to 6, the test piece was immersed in the first pH / oxidation-reduction potential adjusted water W1 for 1 minute and then in the second pH / oxidation-reduction potential adjusted water W2 for 1 minute, and this cycle was repeated five times in the same manner as in Example 1. The wiring portion of the Co pattern wafer was then observed with an XSEM to measure the cobalt metal loss. The results are shown in Figure 7.

[0091] As is clear from Figure 7, when the metal loss of cobalt was examined when the second pH / oxidation-reduction potential adjusted water W2 was an acid other than citric acid (formic acid), the average metal loss was 25 nm / 10 minutes in Example 7, which used citric acid, whereas the average metal loss in Example 8 was 9 nm / 10 minutes, and the average metal loss in Example 9 was 34 nm / 10 minutes. In Example 8, the metal loss of cobalt varied slightly depending on the line width, and pattern loading occurred. In Example 9, the metal loss of cobalt hardly varied depending on the line width. These findings demonstrate that pattern loading did not occur. Since the pH of the second pH / oxidation-reduction potential adjusted water W2 in Example 7 was approximately 2.8, the pH of the second pH / oxidation-reduction potential adjusted water W2 in Example 8 was approximately 4.4, and the pH of the second pH / oxidation-reduction potential adjusted water W2 in Example 9 was approximately 3.1, it can be inferred that the pH of the second pH / oxidation-reduction potential adjusted water W2 is important for extremely minutely dissolving a predetermined amount of cobalt without causing pattern loading.

[0092] As is clear from Examples 1 to 9, the pH / oxidation-reduction potential adjusted water manufacturing apparatus of the present invention can manufacture two types of processing solutions with different pHs and oxidation-reduction potentials for wafer processing. This makes it possible to dissolve a predetermined amount of wiring metal in the semiconductor wiring manufacturing process by combining various types of pH adjusters and oxidation-reduction potential adjusters and their amounts (pH, oxidation-reduction potential) depending on the semiconductor wiring material and processing time. [Explanation of symbols]

[0093] 1. pH / oxidation-reduction potential adjusted water production device 2 supply lines 3. Platinum group metal-loaded resin column (hydrogen peroxide removal mechanism) 4. First Adjusted Water Production Line 41 pH adjuster tank 41A pH adjuster injection line 41B Liquid supply mechanism 42 Oxidation-reduction potential adjuster tank 42A Oxidation-reduction potential adjuster injection line 42B Liquid supply mechanism 43 First Reservoir 44 On-off valve 47 First Degassing Membrane Device 47A Vacuum Pump 48 First Gas Dissolution Membrane Device 5. Second adjusted water production line 51 pH adjuster tank 51A pH adjuster injection line 51B Liquid supply mechanism 52 Oxidation-reduction potential adjuster tank 52A Oxidation-reduction potential adjuster injection line 52B Liquid supply mechanism 53 Second Reservoir 54 On-off valve 55 Bypass Line 56 On-off valve 57 Second degassing membrane device 57A Vacuum Pump 58 Second gas dissolution membrane device 61 N2 gas (inert gas) supply pipe 71 First Gas Dissolution Membrane Device 72 Second gas dissolution membrane device W Ultrapure water W1 First pH / oxidation-reduction potential adjusted water W2 First pH / oxidation-reduction potential adjusted water UP Use Points

Claims

1. A pH / oxidation-reduction potential adjusted water manufacturing apparatus for manufacturing cleaning water having a desired pH and oxidation-reduction potential by adding a pH adjuster and an oxidation-reduction potential adjuster to ultrapure water, The pH / oxidation-reduction potential adjusted water is used in the manufacture of semiconductor wiring using cobalt as a wiring metal, The ultrapure water supply line has a hydrogen peroxide removal mechanism, a branch flow path branched into two or more branches at a downstream stage of the hydrogen peroxide removal mechanism; a pH adjusting mechanism for adding a pH adjuster and an oxidation-reduction potential adjusting mechanism for adding an oxidation-reduction potential adjuster, which are provided in each of the branched flow paths; an adjusted water quality monitoring mechanism that measures the quality of pH / oxidation-reduction potential adjusted water and is provided downstream of the pH adjustment mechanism and the oxidation-reduction potential adjustment mechanism; an addition amount control mechanism that adjusts the amount of pH adjuster added from the pH adjustment mechanism and the amount of redox potential adjuster added from the redox potential adjustment mechanism based on the measurement results of the adjusted water quality monitoring mechanism; a reservoir tank for storing pH / oxidation-reduction potential adjusted water provided in each of the branch flow paths; Equipped with Two or more types of pH / oxidation-reduction potential adjusted water can be supplied from the two or more branch flow paths, At least one of the two or more pH / oxidation-reduction potential adjusted waters has a pH of 9 or more and 13 or less when the pH adjuster is ammonia, and an oxidation-reduction potential of 0 V or more and 1.7 V or less when the oxidation-reduction potential adjuster is hydrogen peroxide; A pH / oxidation-reduction potential adjusted water manufacturing apparatus, wherein at least one of the two or more types of pH / oxidation-reduction potential adjusted water has a pH of 0 or more and 3.5 or less when the pH adjuster is one or more selected from the group consisting of citric acid, formic acid, and carbon dioxide gas.

2. 2. The pH / oxidation-reduction potential adjusted water producing apparatus of claim 1, wherein the pH adjuster is one selected from the group consisting of ammonia, citric acid, and formic acid, and is injected into the ultrapure water supply line by a pump or a pressurizing means using a sealed tank and an inert gas.

3. 2. The pH / oxidation-reduction potential adjusted water producing apparatus according to claim 1, wherein the pH adjuster is carbon dioxide gas and is added by gas dissolution using a gas-permeable membrane module or a direct gas-liquid contact device such as an ejector.

4. 4. The pH / oxidation-reduction potential adjusted water producing apparatus according to claim 1, wherein the storage tank for the pH / oxidation-reduction potential adjusted water has a mechanism for supplying an inert gas.

5. A method for producing pH / oxidation-reduction potential adjusted water, which comprises adding a pH adjuster and an oxidation-reduction potential adjuster to ultrapure water to produce cleaning water having a desired pH and oxidation-reduction potential, The pH / oxidation-reduction potential adjusted water is used in the manufacture of semiconductor wiring using cobalt as a wiring metal, removing hydrogen peroxide from the ultrapure water by a hydrogen peroxide removal mechanism provided in the ultrapure water supply line; branching the ultrapure water from which the hydrogen peroxide has been removed into two or more branch flow paths; adjusting the pH of the ultrapure water from which the hydrogen peroxide has been removed by a pH adjusting mechanism; adjusting the oxidation-reduction potential of the ultrapure water after removing the hydrogen peroxide by an oxidation-reduction potential adjusting mechanism; a step of measuring the quality of the pH / oxidation-reduction potential adjusted water after adjusting the pH and oxidation-reduction potential using an adjusted water quality monitoring mechanism; a step of controlling the amount of pH adjuster added from the pH adjustment mechanism and the amount of redox potential adjuster added from the redox potential adjustment mechanism based on the measurement results of the adjusted water quality monitoring mechanism; storing the pH / oxidation-reduction potential adjusted water in storage tanks provided in the two or more branch flow paths, respectively; Equipped with Two or more types of pH / oxidation-reduction potential adjusted water can be supplied from the two or more branch flow paths, At least one of the two or more pH / oxidation-reduction potential adjusted waters has a pH of 9 or more and 13 or less when the pH adjuster is ammonia, and an oxidation-reduction potential of 0 V or more and 1.7 V or less when the oxidation-reduction potential adjuster is hydrogen peroxide; A method for producing pH / oxidation-reduction potential adjusted water, wherein at least one other of the two or more types of pH / oxidation-reduction potential adjusted water has a pH of 0 or more and 3.5 or less when the pH adjuster is one or more selected from the group consisting of citric acid, formic acid, and carbon dioxide gas.

6. 6. A method for producing pH / oxidation-reduction potential adjusted water as described in claim 5, wherein the pH adjuster is one selected from the group consisting of ammonia, citric acid, and formic acid, and is injected into the ultrapure water supply line by a pump or a pressurizing means using a sealed tank and an inert gas.

7. 6. The method for producing pH / oxidation-reduction potential adjusted water according to claim 5, wherein the pH adjuster is carbon dioxide gas and is added by gas dissolution using a gas-permeable membrane module or a direct gas-liquid contact device such as an ejector.

8. 8. The method for producing pH / oxidation-reduction potential adjusted water according to claim 5, wherein the storage tank for the pH / oxidation-reduction potential adjusted water is purged with an inert gas.

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