JP5254672B2 - Chemical supply method and chemical supply device - Google Patents
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本発明は、半導体製造工程のうち、スラリーを使用する化学機械的研磨工程（ＣＭＰ：Chemical Mechanical Polishing）（以下、ＣＭＰと称す）に薬液を供給する薬液供給方法及び薬液供給装置に関する。 The present invention relates to a chemical supply method and a chemical supply apparatus for supplying a chemical to a chemical mechanical polishing (CMP) process (hereinafter referred to as CMP) using a slurry in a semiconductor manufacturing process.
半導体デバイスや液晶の駆動デバイスなどの集積回路を製造するに際して、ＣＭＰは層間絶縁膜、シャロー・トレンチ分離用絶縁膜、導電性金属膜等の複数の膜に対して平坦化の目的で用いられているが、特に導電性金属膜の平坦化を目的とする場合は酸化力を有する成分を必須としている。特に最近では、ダマシン法により銅配線を形成する際のＣＭＰ工程では、二酸化ケイ素、酸化アルミニウム、酸化セリウム、窒化ケイ素、酸化ジルコニウムなどの砥粒を含むスラリーに、酸化剤として過硫酸アンモニウム、過硫酸カリウム、過酸化水素水、硝酸第二鉄、硝酸第二アンモニウムセリウムなどのいずれかを混合させるが、なかでも、過硫酸塩は過酸化水素よりも酸化電位が高いため、その酸化力が高く、配線材料である銅やバリア膜であるタンタルやタンタル化合物を研磨する際の研磨特性がすぐれており最も有力な候補と言える。その反応式の一例は、以下の通りである。 In manufacturing integrated circuits such as semiconductor devices and liquid crystal drive devices, CMP is used for planarization of a plurality of films such as an interlayer insulating film, an insulating film for shallow trench isolation, and a conductive metal film. However, a component having an oxidizing power is indispensable particularly for the purpose of planarizing the conductive metal film. Particularly recently, in the CMP process when forming a copper wiring by the damascene method, a slurry containing abrasive grains such as silicon dioxide, aluminum oxide, cerium oxide, silicon nitride, zirconium oxide, and ammonium persulfate and potassium persulfate as oxidants. , Hydrogen peroxide solution, ferric nitrate, cerium nitrate cerium nitrate, etc., but persulfate has a higher oxidation potential than hydrogen peroxide, so its oxidizing power is high. It has excellent polishing characteristics when polishing copper, which is a material, and tantalum, which is a barrier film, and tantalum compounds. An example of the reaction formula is as follows.
２Ｈ2Ｏ→Ｈ2Ｏ2＋２Ｈ+＋２e−Ｅ0＝１．７８Ｖ 2H 2 O → H 2 O 2 + 2H + +2 e −E 0 = 1.78V
２ＳＯ4 2-→Ｓ2Ｏ8 2-＋２e−Ｅ0＝２．０１Ｖ 2SO 4 2- → S 2 O 8 2- +2 e -E 0 = 2.01 V
しかしながら、過硫酸塩を含む溶液は他の酸化剤と比べて分解が早く、溶液で輸送する場合は１０度以下に保冷して輸送しなければならない制約があるため、通常は粉末または固体として輸送し半導体製造工場内で溶解している。 However, a solution containing a persulfate salt decomposes faster than other oxidizing agents, and when transported in solution, there is a restriction that it must be transported while being kept at a temperature of 10 degrees or less. It is dissolved in the semiconductor manufacturing factory.
半導体製造工場内で粉末または固体を溶解して所望の濃度に調合して供給する場合も経時的な分解を起こすため、溶解後に過硫酸の酸化力が保たれている一定時間内でできるだけ使い切るような運用を行いながら、一定時間を経過した場合は破棄することが多い。しかしながらこの方法だけでは、その過硫酸塩の溶解後の溶液の保管条件や環境変化の影響による分解速度の変化をとらえることができず、保管条件や環境変化の影響に対するマージンをおかなければならず破棄する量が多い。また半導体工場の生産量は常に一定ではないため、生産量が低下した場合は残液の量が更に多くなる傾向にある。 Even when powder or solid is dissolved and mixed to the desired concentration in a semiconductor manufacturing factory, it will decompose over time, so that it will be used up as much as possible within a certain time when the oxidizing power of persulfuric acid is maintained after dissolution. When a certain period of time has elapsed while performing a simple operation, the data is often discarded. However, this method alone cannot capture changes in the decomposition rate due to the storage conditions and environmental changes of the solution after dissolution of the persulfate, and a margin for the effects of storage conditions and environmental changes must be kept. A lot to discard. In addition, since the production volume of the semiconductor factory is not always constant, when the production volume decreases, the amount of residual liquid tends to increase further.
上記の問題に対し、従来はこれを防ぐためには一定量のサンプリングを行い、酸化還元滴定法分析またはイオンクロマト法などを行うことにより濃度を確認しながら使用可能か破棄するかどうかを判断している。
酸化還元滴定法については、ＪＩＳ Ｋ８２５２に記載のペルオキソ二硫酸の純度を確認する試験方法が紹介されている（非特許文献１参照）。
In order to prevent this problem, a certain amount of sampling has been performed in the past, and by using redox titration analysis or ion chromatography, etc., it is determined whether it can be used or discarded while checking the concentration. Yes.
As for the oxidation-reduction titration method, a test method for confirming the purity of peroxodisulfuric acid described in JIS K8252 has been introduced (see Non-Patent Document 1).
然るに、酸化還元滴定法やイオンクロマト法はいずれもサンプリングを必要とするオフラインの分析であり、酸化還元滴定法では滴定にて終点を求めるための時間が必要であり、イオンクロマト法ではカラムでの反応時間であるリテンションタイムを必要とするため、いずれも長時間を要し、また分析操作が複雑である。 However, both the redox titration method and the ion chromatographic method are off-line analyzes that require sampling. The redox titration method requires time for determining the end point by titration. Since a retention time, which is a reaction time, is required, both require a long time and the analysis operation is complicated.
また、従来の他の方法としては、Ｎ，Ｎ−ジエチル−ｐ−フェニレンジアミン硫酸塩とヨウ化カリウムとを添加して反応させ、反応液の発色度合を比色法により排水中のペルオキソ二硫酸を短時間で測定する方法が公開されているが、やはりこれも自動化には適するもののオフラインの分析であり、発色までの化学反応時間が必要であり時間的なロスという課題が残ると同時に、試薬の準備や発色反応後の廃液の処理といった追加コストを生じることになる（特許文献１参照）。 Further, as another conventional method, N, N-diethyl-p-phenylenediamine sulfate and potassium iodide are added and reacted, and the degree of coloration of the reaction solution is determined by a colorimetric method. Although a method for measuring urine in a short time has been published, this is also suitable for automation, but it is an off-line analysis, requiring a chemical reaction time until color development, and the problem of time loss remains. Additional costs such as the preparation of the liquid and the treatment of the waste liquid after the color reaction (see Patent Document 1).
このように、従来の測定方法では、いずれの方法においても、オフラインによる分析であり、操作が複雑となり且つ時間的なロスがあり、また試薬や廃液の処理コストを追加的に発生させるという課題がある。 As described above, the conventional measurement method is an off-line analysis in any of the methods, and there are problems that the operation is complicated and there is a time loss, and the processing cost of reagents and waste liquid is additionally generated. is there.
本発明が解決しようとする課題は、上記従来の問題点を解決し、薬液の供給装置において過硫酸塩溶液の初期濃度における導電率と薬液供給時における導電率を測定することにより、過硫酸塩溶液の濃度を管理する方法を提供するとともに、この方法を用いて管理された薬液を供給することによりＣＭＰ工程における不良の発生を未然に防止して歩留まりを向上できるようにせしめることにある。 The problem to be solved by the present invention is to solve the above-mentioned conventional problems, by measuring the conductivity at the initial concentration of the persulfate solution and the conductivity at the time of supplying the chemical solution in the chemical solution supply apparatus, In addition to providing a method for managing the concentration of the solution, it is intended to prevent the occurrence of defects in the CMP process and improve the yield by supplying a chemical solution managed using this method.
本発明は、上記課題を解決するため、化学機械的研磨工程に過硫酸塩を含む薬液を供給する薬液供給方法において、
粉末または固形物の過硫酸塩に溶媒を加えて溶解して低濃度から高濃度に亘る各種濃度の過硫酸塩溶液を作成し、任意の温度における溶解直後の各種濃度の過硫酸塩溶液の初期濃度（Ｃｎ）の導電率（Ｅｎ）を測定する工程と、
前記任意の温度における溶解直後の各種濃度の過硫酸塩溶液の導電率（Ｅｎ）と前記任意の温度における溶解直後の過硫酸塩溶液の初期濃度（Ｃｎ）との関係を示す関数である式（１）を予め作成する工程と、
式（１）より前記任意の温度における溶解直後の各種濃度の過硫酸塩溶液の導電率（Ｅｎ）における過硫酸塩溶液の初期濃度（Ｃｎ）を算出する工程と、
前記任意の温度における薬液供給時の過硫酸塩溶液の導電率（ｅｎ）を測定する工程と、
前記任意の温度における溶解直後の各種濃度の過硫酸塩溶液の初期濃度（Ｃｎ）と薬液供給時の分解変化率（ΔＣｎ）／（ΔＥｎ）との関係を示す関数である式（２）を予め作成する工程と、
式（２）より、前記任意の温度における溶解直後の各種濃度の過硫酸塩溶液の初期濃度（Ｃｎ）における薬液供給時の分解変化率
（ΔＣｎ）／（ΔＥｎ）を算出する工程と、
前記工程により測定及び算出した、前記溶解直後の過硫酸塩溶液の初期濃度（Ｃｎ）と、薬液供給時の過硫酸塩溶液の分解変化率
（ΔＣｎ）／（ΔＥｎ）と、前記薬液供給時の過硫酸塩溶液の導電率の変化量（ΔＥｎ）とを式（３）に代入し、薬液供給時の過硫酸塩溶液の濃度（残存する過硫酸塩の濃度）（Ｃ）を求める工程とよりなる、
化学機械的研磨工程に供給する過硫酸塩を含む薬液の濃度を管理することを特徴とする薬液供給方法を構成したことにある。
（Ｃｎ）＝α（Ｅｎ） （１）
（ΔＣｎ）／（ΔＥｎ）＝β（Ｃｎ） （２）
（Ｃ）＝（Ｃｎ）−｛（ΔＣｎ）／（ΔＥｎ）｝×（ΔＥｎ） （３）
（ただし、本明細書において、（ΔＣｎ）は、溶解直後における過硫酸塩溶液の初期濃度と薬液供給時の濃度との変化量であり、（ΔＥｎ）は、溶解直後における過硫酸塩溶液の導電率と薬液供給時の導電率との変化量を意味する。）
In order to solve the above problems, the present invention provides a chemical solution supplying method for supplying a chemical solution containing a persulfate to a chemical mechanical polishing step.
A persulfate solution of various concentrations ranging from low to high is prepared by adding a solvent to powder or solid persulfate to dissolve, and the initial concentration of the persulfate solution immediately after dissolution at any temperature Measuring the conductivity (En) of concentration (Cn);
An expression that is a function showing the relationship between the conductivity (En) of the persulfate solution of various concentrations immediately after dissolution at the arbitrary temperature and the initial concentration (Cn) of the persulfate solution immediately after dissolution at the arbitrary temperature ( 1) creating in advance;
Calculating the initial concentration (Cn) of the persulfate solution in the conductivity (En) of the persulfate solution of various concentrations immediately after dissolution at the arbitrary temperature from the equation (1);
Measuring the conductivity (en) of the persulfate solution when supplying the chemical solution at the arbitrary temperature;
Formula (2), which is a function showing the relationship between the initial concentration (Cn) of the persulfate solution of various concentrations immediately after dissolution at the arbitrary temperature and the degradation change rate (ΔCn) / (ΔEn) at the time of supplying the chemical solution, Creating a process;
From the equation (2), calculating a decomposition change rate (ΔCn) / (ΔEn) at the time of supplying a chemical solution at an initial concentration (Cn) of a persulfate solution having various concentrations immediately after dissolution at the arbitrary temperature;
The initial concentration (Cn) of the persulfate solution immediately after dissolution, measured and calculated by the above step, the rate of change in decomposition of the persulfate solution at the time of supplying the chemical solution (ΔCn) / (ΔEn), and the value at the time of supplying the chemical solution Substituting the amount of change in electrical conductivity of the persulfate solution (ΔEn) into equation (3) to obtain the concentration of the persulfate solution (concentration of the remaining persulfate) (C) when supplying the chemical solution Become,
A chemical solution supply method is characterized in that the concentration of a chemical solution containing persulfate supplied to the chemical mechanical polishing step is controlled.
(Cn) = α (En) (1)
(ΔCn) / (ΔEn) = β (Cn) (2)
(C) = (Cn) − {(ΔCn) / (ΔEn)} × (ΔEn) (3)
(However, in this specification, (ΔCn) is the amount of change between the initial concentration of the persulfate solution immediately after dissolution and the concentration at the time of chemical supply, and (ΔEn) is the conductivity of the persulfate solution immediately after dissolution.) It means the amount of change between the rate and the conductivity when supplying chemicals.)
また、第２の解決課題は、前記の過硫酸塩が過硫酸アンモニウムである薬液供給方法を構成したことにある。 A second problem to be solved is that a chemical supply method in which the persulfate is ammonium persulfate is configured.
また、第３の解決課題は、前記の過硫酸塩を含む薬液が化学機械的研磨工程用の砥粒含むスラリーを混合した薬液である薬液供給方法を構成したことにある。 A third problem to be solved is that a chemical solution supplying method is provided in which the chemical solution containing the persulfate is a chemical solution obtained by mixing slurry containing abrasive grains for the chemical mechanical polishing process.
また、第４の解決課題は、化学機械的研磨工程に過硫酸塩を含む薬液を供給する薬液供給装置において、
粉末または固形物の過硫酸塩に溶媒を加えて溶解して低濃度から高濃度に亘る各種濃度の過硫酸塩溶液を作成し、任意の温度における溶解直後の各種濃度の過硫酸塩溶液の初期濃度（Ｃｎ）の導電率（Ｅｎ）を測定する工程と、
前記任意の温度における溶解直後の各種濃度の過硫酸塩溶液の導電率（Ｅｎ）と前記任意の温度における溶解直後の過硫酸塩溶液の初期濃度（Ｃｎ）との関係を示す関数である式（１）を予め作成する工程と、
式（１）より前記任意の温度における溶解直後の各種濃度の過硫酸塩溶液の導電率（Ｅｎ）における過硫酸塩溶液の初期濃度（Ｃｎ）を算出する工程と、
前記任意の温度における薬液供給時の過硫酸塩溶液の導電率（ｅｎ）を測定する工程と、
前記任意の温度における溶解直後の各種濃度の過硫酸塩溶液の初期濃度（Ｃｎ）と薬液供給時の分解変化率（ΔＣｎ）／（ΔＥｎ）との関係を示す関数である式（２）を予め作成する工程と、
式（２）より、前記任意の温度における溶解直後の各種濃度の過硫酸塩溶液の初期濃度（Ｃｎ）における薬液供給時の分解変化率
（ΔＣｎ）／（ΔＥｎ）を算出する工程と、
前記工程により測定及び算出した、前記溶解直後の過硫酸塩溶液の初期濃度（Ｃｎ）と、薬液供給時の過硫酸塩溶液の分解変化率
（ΔＣｎ）／（ΔＥｎ）と、前記薬液供給時の過硫酸塩溶液の導電率の変化量（ΔＥｎ）とを式（３）に代入し、薬液供給時の過硫酸塩溶液の濃度（残存する過硫酸塩の濃度）（Ｃ）を求める工程とよりなる、
化学機械的研磨工程に供給する過硫酸塩を含む薬液の濃度を管理する機能を備えた薬液供給装置を構成したことにある。
（Ｃｎ）＝α（Ｅｎ） （１）
（ΔＣｎ）／（ΔＥｎ）＝β（Ｃｎ） （２）
（Ｃ）＝（Ｃｎ）−｛（ΔＣｎ）／（ΔＥｎ）｝×（ΔＥｎ） （３）
A fourth problem to be solved is a chemical supply apparatus for supplying a chemical containing persulfate to the chemical mechanical polishing process.
A persulfate solution of various concentrations ranging from low to high is prepared by adding a solvent to powder or solid persulfate to dissolve, and the initial concentration of the persulfate solution immediately after dissolution at any temperature Measuring the conductivity (En) of concentration (Cn);
An expression that is a function showing the relationship between the conductivity (En) of the persulfate solution of various concentrations immediately after dissolution at the arbitrary temperature and the initial concentration (Cn) of the persulfate solution immediately after dissolution at the arbitrary temperature ( 1) creating in advance;
Calculating the initial concentration (Cn) of the persulfate solution in the conductivity (En) of the persulfate solution of various concentrations immediately after dissolution at the arbitrary temperature from the equation (1);
Measuring the conductivity (en) of the persulfate solution when supplying the chemical solution at the arbitrary temperature;
Formula (2), which is a function showing the relationship between the initial concentration (Cn) of the persulfate solution of various concentrations immediately after dissolution at the arbitrary temperature and the degradation change rate (ΔCn) / (ΔEn) at the time of supplying the chemical solution, Creating a process;
From the equation (2), calculating a decomposition change rate (ΔCn) / (ΔEn) at the time of supplying a chemical solution at an initial concentration (Cn) of a persulfate solution having various concentrations immediately after dissolution at the arbitrary temperature;
The initial concentration (Cn) of the persulfate solution immediately after dissolution, measured and calculated by the above step, the rate of change in decomposition of the persulfate solution at the time of supplying the chemical solution (ΔCn) / (ΔEn), and the value at the time of supplying the chemical solution Substituting the amount of change in electrical conductivity of the persulfate solution (ΔEn) into equation (3) to obtain the concentration of the persulfate solution (concentration of the remaining persulfate) (C) when supplying the chemical solution Become,
A chemical solution supply apparatus having a function of managing the concentration of a chemical solution containing persulfate supplied to the chemical mechanical polishing process is provided.
(Cn) = α (En) (1)
(ΔCn) / (ΔEn) = β (Cn) (2)
(C) = (Cn) − {(ΔCn) / (ΔEn)} × (ΔEn) (3)
本発明による薬液供給方法及び薬液供給装置によれば、薬液の供給装置において過硫酸塩溶液の初期濃度における導電率と薬液供給時における導電率を測定するだけで、過硫酸塩溶液の濃度を管理する方法を提供するとともに、管理された薬液を供給することによりＣＭＰ工程における不良の発生を未然に防止して、歩留まりを向上できる。即ち、本発明によれば、粉末または固形物の過硫酸塩を溶媒に溶解して所望濃度の過硫酸溶液とし、溶解後に導電率を測定することによって過硫酸塩の成分濃度を求め、その後導電率の変化を計測することによって過硫酸塩の分解率を捉えることにより、分解後の有効過硫酸塩成分の濃度を計算して、酸化力の低下を管理することができる。 According to the chemical solution supply method and the chemical solution supply apparatus according to the present invention, the concentration of the persulfate solution can be managed only by measuring the conductivity at the initial concentration of the persulfate solution and the conductivity at the time of supplying the chemical solution in the chemical solution supply apparatus. In addition, by providing a controlled chemical solution, it is possible to prevent the occurrence of defects in the CMP process and improve the yield. That is, according to the present invention, powder or solid persulfate is dissolved in a solvent to obtain a persulfate solution having a desired concentration, and the concentration of the persulfate component is determined by measuring the conductivity after dissolution, and then the conductivity is measured. By measuring the rate of change of the persulfate by measuring the change in rate, the concentration of the effective persulfate component after the decomposition can be calculated to manage the reduction in oxidizing power.
以下に本発明の詳細を説明する。
ＣＭＰ工程に薬液を供給するにあたり、一定量の粉末または固形物の過硫酸塩を溶媒に溶解して所望濃度の過硫酸溶液に調合するが、任意の温度における溶解直後の過硫酸塩の初期濃度（Ｃｎ）と導電率（Ｅｎ）との間の関係は、次の関数で表すことが出来る。
（Ｃｎ）＝α（Ｅｎ） （１）
Details of the present invention will be described below.
In supplying a chemical solution to the CMP process, a certain amount of powder or solid persulfate is dissolved in a solvent to prepare a persulfate solution having a desired concentration, but the initial concentration of persulfate immediately after dissolution at an arbitrary temperature. The relationship between (Cn) and conductivity (En) can be expressed by the following function.
(Cn) = α (En) (1)
半導体や液晶のＣＭＰ工程では塩としてアルカリ金属は好ましくないため通常はアンモニウム塩などアルカリ金属ではない塩が用いられる。例えば過硫酸アンモニウムの粉末または固形物を水に溶解すると下記の化学式のように、イオン化をともなって解離する。 In the CMP process of semiconductors and liquid crystals, alkali metals are not preferred as salts, and therefore salts that are not alkali metals such as ammonium salts are usually used. For example, when ammonium persulfate powder or solid is dissolved in water, it dissociates with ionization as shown in the following chemical formula.
（ＮＨ4）2Ｓ2Ｏ8＋２（Ｈ2Ｏ）→２（ＮＨ4）+＋Ｓ2Ｏ8 2-＋２ＯＨ-＋２Ｈ+ (NH 4 ) 2 S 2 O 8 +2 (H 2 O) → 2 (NH 4 ) + + S 2 O 8 2− + 2OH − + 2H +
過硫酸アンモニウムは溶解するとアンモニウムイオンと過硫酸イオンを生じ、この系内には水酸イオンや水素イオンが存在する。溶解直後は分解が進んでいないため、これらのイオンの総量と相関する導電率から濃度を計測できる。溶液の導電率は溶かし込む過硫酸アンモニウムの量との関係を示す関数である式（１）は、以下に示す実験の結果、通常、比例関係となることが判明した。
本発明では、あらかじめ、任意の温度における、上記の導電率と過硫酸塩の初期濃度の関係を求めた検量線を得ることによって、溶解直後の導電率値から過硫酸塩の初期濃度を求める。つづいて過硫酸塩は、下記の化学式のように時間経過とともに硫酸イオンと過酸化水素に分解していく。
When ammonium persulfate is dissolved, ammonium ions and persulfate ions are produced, and hydroxide ions and hydrogen ions are present in this system. Since decomposition does not proceed immediately after dissolution, the concentration can be measured from the electrical conductivity that correlates with the total amount of these ions. As a result of the following experiment, it has been found that the equation (1), which is a function indicating the relationship between the conductivity of the solution and the amount of ammonium persulfate to be dissolved, is generally proportional.
In the present invention, the initial concentration of persulfate is obtained from the conductivity value immediately after dissolution by obtaining a calibration curve for the relationship between the conductivity and the initial concentration of persulfate at an arbitrary temperature. Subsequently, persulfate is decomposed into sulfate ions and hydrogen peroxide over time as shown in the chemical formula below.
2(NH4)+＋S2O8 2-＋2OH-＋2H+→2(NH4)+＋2SO4 2-＋2H+＋H2O2 2 (NH 4) + + S 2 O 8 2- + 2OH - + 2H + → 2 (NH 4) + + 2SO 4 2- + 2H + + H 2 O 2
過酸化水素から更に分解が進めば、下記の式に示す通り、酸素を生じて系外へ出て行くことになる。 If further decomposition proceeds from hydrogen peroxide, oxygen is generated and goes out of the system as shown in the following formula.
2(NH4)+＋2SO4 2-＋2H+＋H2O2→2(NH4)+＋2SO4 2-＋2H+＋H2O＋1/2O2 2 (NH 4 ) + + 2SO 4 2- + 2H + + H 2 O 2 → 2 (NH 4 ) + + 2SO 4 2- + 2H + + H 2 O + 1 / 2O 2
過硫酸塩は、時間経過や周囲の環境変化により硫酸イオンと過酸化水素に分解するが、ここで過硫酸イオンと水酸イオンの存在量に変化を伴い、それらが減少し、かつ硫酸イオンが増加するため、導電率計にてその変化を迅速且つ簡便に捉えることができる。１モルの過硫酸が分解して２モルの硫酸イオンになるとき１モルの過酸化水素が生じると同時に系内には導電率を高くするイオンの存在比が多くなり、導電率が敏感に上昇変化する。ここの変化率から分解した量を計算することができる。 Persulfate is decomposed into sulfate ions and hydrogen peroxide with the passage of time and the surrounding environment, but here the amount of persulfate ions and hydroxide ions is changed, they are decreased, and sulfate ions are reduced. Since it increases, the change can be quickly and easily grasped by the conductivity meter. When 1 mol of persulfuric acid is decomposed to 2 mol of sulfate ion, 1 mol of hydrogen peroxide is generated. At the same time, the abundance ratio of ions that increase the conductivity in the system increases, and the conductivity increases sensitively. Change. The decomposed amount can be calculated from the rate of change here.
本発明者による実験の結果、後述するように、任意の温度における、過硫酸塩の初期濃度（Ｃｎ）は、その分解変化率（ΔＣｎ）／（ΔＥｎ）と非常に相関関係が高い。したがって、任意の温度における、各過硫酸塩濃度において予め過硫酸塩溶液の初期濃度（Ｃｎ）と過硫酸塩の分解率（ΔＣｎ）／（ΔＥｎ）との関係を求めた検量線を得ることによって、導電率変化率から過硫酸塩の分解率を求めることができることが判明した。任意の温度における、各過硫酸塩の初期濃度（Ｃ１・・・Ｃｎ）における過硫酸塩溶液の分解変化率（ΔＣｎ）／（ΔＥｎ）と初期濃度（Ｃｎ）の関係を示す関数は、式（２）で表すことが出来る。
（ΔＣｎ）／（ΔＥｎ）＝β（Ｃｎ） （２）
上記式（１）式と（２）と初期と薬液供給時の任意の温度における、導電率の変化（ΔＥ）を組み合わせることにより、分解が進んだあとも過硫酸塩の濃度をモニタリングすることができる。
前記工程により求められた、前記溶解直後の過硫酸塩溶液の初期濃度（Ｃｎ）における導電率（Ｅｎ）と薬液供給時の過硫酸塩溶液の導電率（ｅｎ）の変化量（ΔＥｎ）＝（ｅｎ）−（Ｅｎ）と、初期濃度（Ｃｎ）、過硫酸塩溶液の分解変化率（ΔＣｎ）／（ΔＥｎ）との関係から、薬液供給時の濃度（Ｃ）（残存する過硫酸塩の濃度）を示す関数は、式（３）で表すことができる。
（Ｃ）＝（Ｃｎ）−｛（ΔＣｎ）／（ΔＥｎ）｝×（ΔＥｎ） （３）
すなわち、任意の温度における、初期の過硫酸塩の濃度を導電率からもとめると共に、導電率を計測しておき、その後、任意の温度における、初期濃度に対する導電率の差分から分解した過硫酸塩の濃度を求めて、初期濃度より減ずることにより、残存する過硫酸塩の濃度を求めることができる。
As a result of experiments by the present inventor, as will be described later, the initial concentration (Cn) of persulfate at an arbitrary temperature has a very high correlation with the decomposition change rate (ΔCn) / (ΔEn). Therefore, by obtaining a calibration curve that previously obtained the relationship between the initial concentration (Cn) of the persulfate solution and the decomposition rate (ΔCn) / (ΔEn) of the persulfate solution at each temperature at each persulfate concentration. It was found that the decomposition rate of persulfate can be obtained from the rate of change in conductivity. The function indicating the relationship between the persulfate solution decomposition change rate (ΔCn) / (ΔEn) and the initial concentration (Cn) at the initial concentration (C1... Cn) of each persulfate at an arbitrary temperature is expressed by the equation ( 2).
(ΔCn) / (ΔEn) = β (Cn) (2)
By combining the above formulas (1) and (2) with the change in electrical conductivity (ΔE) at an initial temperature and at any temperature during chemical supply, the concentration of persulfate can be monitored even after decomposition has progressed. it can.
The amount of change (ΔEn) = (conductivity (En) in the initial concentration (Cn) of the persulfate solution immediately after dissolution, and the conductivity (en) of the persulfate solution at the time of supplying the chemical solution, determined by the above step) en)-(En), the initial concentration (Cn), and the rate of change in decomposition of the persulfate solution (ΔCn) / (ΔEn), the concentration at the time of supplying the chemical solution (C) (the concentration of the remaining persulfate) ) Can be expressed by equation (3).
(C) = (Cn) − {(ΔCn) / (ΔEn)} × (ΔEn) (3)
That is, the initial persulfate concentration at an arbitrary temperature is obtained from the conductivity, and the conductivity is measured, and then the persulfate decomposed from the difference in the conductivity with respect to the initial concentration at an arbitrary temperature. By determining the concentration and reducing it from the initial concentration, the concentration of the remaining persulfate can be determined.
本発明では、ＣＭＰに必要な過硫酸塩の有効成分濃度をインラインで即時に正確に測定できる点から、導電率測定部及び温度測定部の検出器が比較的小型であることが好ましい。
過硫酸塩溶液の導電率は、濃度が同じ場合は温度によって変わり、一般的には温度が高くなるほど、導電率は高くなる傾向にあるため、温度測定もあわせて行い基準温度へ換算すべく補正をする必要がある。装置には、導電率、および温度測定値を濃度に変換表示できるソフトプログラム機能を付与することが好ましい。
In the present invention, it is preferable that the detectors of the conductivity measuring unit and the temperature measuring unit are relatively small because the active ingredient concentration of persulfate necessary for CMP can be accurately measured immediately in-line.
The conductivity of the persulfate solution varies depending on the temperature when the concentration is the same. Generally, the higher the temperature is, the higher the conductivity tends to increase. It is necessary to do. The apparatus is preferably provided with a soft program function capable of converting and displaying the conductivity and temperature measurement values as concentrations.
本発明において、導電率測定装置、温度測定装置自体に特に制限はなく、市販のものでよいが、測定感度の高いもの且つ測定装置からのパーティクルや構成成分の溶出のないものが好ましい。 In the present invention, the conductivity measuring device and the temperature measuring device are not particularly limited and may be commercially available, but those having high measurement sensitivity and free from elution of particles and components from the measuring device are preferable.
以下、本発明の具体的な実施の一例を示す。以下の実施例はあくまで一つの例であり、本発明を何ら限定するものではない。 Hereinafter, an example of specific implementation of the present invention will be shown. The following examples are merely examples, and do not limit the present invention.
＜実施例１＞
未知資料１の過硫酸アンモニウム（ＡＰＳ）を超純水に溶解し、溶解直後の導電率を測定し、分解放置後再度導電率を測定した。
ここでの初期濃度、導電率の変化は全て液温２０℃での換算値を用いることとする。
過硫酸アンモニウムとしては粉末の過硫酸アンモニウム（ペルオキソ二硫酸アンモニウム）ＪＩＳ試薬特級を用いた。本発明と比較する分析としてＪＩＳ Ｋ８２５２に記載のペルオキソ二硫酸の純度を確認する電位差滴定による方法に則った。
<Example 1>
The ammonium persulfate (APS) of Unknown Document 1 was dissolved in ultrapure water, the conductivity immediately after dissolution was measured, and the conductivity was measured again after being left for decomposition.
Here, the initial concentration and the change in conductivity are all converted values at a liquid temperature of 20 ° C.
As ammonium persulfate, powdery ammonium persulfate (ammonium peroxodisulfate) JIS reagent special grade was used. As an analysis for comparison with the present invention, a method by potentiometric titration for confirming the purity of peroxodisulfuric acid described in JIS K8252 was used.
先ず、未知資料１の過硫酸アンモニウムの溶解直後の導電率を測定したところ、液温３０℃に於いて６．９８２（Ｓ／ｍ）であった。 First, the electrical conductivity immediately after dissolution of ammonium persulfate in Unknown Document 1 was measured and found to be 6.982 (S / m) at a liquid temperature of 30 ° C.
次いで、既知量過硫酸アンモニウムを超純水に溶解させ、液温１０〜３５℃における導電率を計測し、濃度と液温と導電率の関係を予め求めた。その結果を表２及び図１に示した。
Next, a known amount of ammonium persulfate was dissolved in ultrapure water, the conductivity at a liquid temperature of 10 to 35 ° C. was measured, and the relationship between the concentration, the liquid temperature, and the conductivity was obtained in advance. The results are shown in Table 2 and FIG.
その結果、過硫酸アンモニウムの初期濃度（Ｃｎ）における導電率（Ｅｎ）（ｙ軸）と液温（℃）（ｘ軸）との関係を示す関数である式は、１次関数となり、次式（４−１）〜（４−７）となった。
ｙ＝０．０７８８ｘ＋２．７１５（５質量％） （４−１）
ｙ＝０．１５００ｘ＋５．０５７（１０質量％） （４−２）
ｙ＝０．２０９６ｘ＋７．４２３（１５質量％） （４−３）
ｙ＝０．２６７３ｘ＋９．７４３（２０質量％） （４−４）
ｙ＝０．３０２７ｘ＋１２．２２（２５質量％） （４−５）
ｙ＝０．３６９６ｘ＋１３．７７（３０質量％） （４−６）
ｙ＝０．３９２５ｘ＋１５．６３（３５質量％） （４−７）
この式の傾きを用いて、未知の濃度の過硫酸アンモニウムの液温と導電率を測定し、近接する式の傾きを採用することによりその濃度を求めた。
As a result, an equation which is a function indicating the relationship between the conductivity (En) (y axis) and the liquid temperature (° C.) (x axis) at the initial concentration (Cn) of ammonium persulfate is a linear function. 4-1) to (4-7).
y = 0.0788x + 2.715 (5 mass%) (4-1)
y = 0.1500x + 5.057 (10 mass%) (4-2)
y = 0.2096x + 7.423 (15 mass%) (4-3)
y = 0.2673x + 9.743 (20 mass%) (4-4)
y = 0.3027x + 12.22 (25 mass%) (4-5)
y = 0.3696x + 13.77 (30 mass%) (4-6)
y = 0.3925x + 15.63 (35 mass%) (4-7)
Using the slope of this equation, the liquid temperature and conductivity of ammonium persulfate of unknown concentration were measured, and the concentration was determined by adopting the slope of the adjacent equation.
図１を用いて、測定ポイントに最も近い式の傾きを採用し、（４−１）式より、ｙ＝ａｘ＋ｂ式のａ（傾き）に０．０７８８を代入し、更に、上記導電率（Ｅｎ）（ｙ）に６．９８２Ｓ／ｍと、液温（℃）（ｘ）に液温３０℃の値を代入すると、
６．９８２＝０．０７８８×３０＋ｂとなり、切片ｂは、４．６１８
となり、測定サンプルの液温と導電率（Ｅｎ）の関係を表す式（４−１）は、
ｙ＝０．０７８８ｘ＋４．６１８
となることが計算された。
上式を用いて、測定したサンプルの２０℃における初期過硫酸アンモニウムの導電率（Ｅｎ）（ｙ）を求めると、
ｙ＝０．０７８８×２０＋４．６１８＝６．１６４となり、
２０℃における初期過硫酸アンモニウムの導電率（Ｅｎ）は、
６．１９４（Ｓ／ｍ）であると計算された。
Using FIG. 1, the slope of the equation closest to the measurement point is adopted, and 0.0788 is substituted into a (slope) of the equation y = ax + b from the equation (4-1), and the conductivity (En ) Substituting the value of 6.982 S / m for (y) and the liquid temperature (° C.) (x) for the liquid temperature of 30 ° C.
6.982 = 0.0788 × 30 + b, and the intercept b is 4.618.
Equation (4-1) representing the relationship between the liquid temperature of the measurement sample and the conductivity (En) is
y = 0.0788x + 4.618
It was calculated to be.
Using the above equation, the electrical conductivity (En) (y) of the initial ammonium persulfate at 20 ° C. of the measured sample was determined.
y = 0.0788 × 20 + 4.618 = 6.164,
The initial ammonium persulfate conductivity (En) at 20 ° C. is
It was calculated to be 6.194 (S / m).
また、表２より、液温２０℃の時の溶解時における過硫酸アンモニウムの初期濃度（Ｃｎ）（質量％）（ｙ）と導電率（Ｅｎ）（Ｓ／ｍ）（ｘ）との関係は、次式（１）となり、これをグラフにプロットすると、図２が得られ、これを式にあらわすと、１次時関数となり、次の一次関数（１−１）が得られた。
Ｃｎ＝α（Ｅｎ） （１）
ｙ＝１．５４４ｘ−２．４７７ （１−１）
式（１−１）のｘに、２０℃における過硫酸アンモニウムの初期濃度（Ｃｎ）における導電率（Ｅｎ）（Ｓ／ｍ）６．１９４を代入すると、２０℃における過硫酸アンモニウムの初期濃度（Ｃｎ）（質量％）は、７．０８７質量％であると計算された。
From Table 2, the relationship between the initial concentration of ammonium persulfate (Cn) (mass%) (y) and the conductivity (En) (S / m) (x) during dissolution at a liquid temperature of 20 ° C. is When the following equation (1) is obtained and this is plotted on a graph, FIG. 2 is obtained. When this is expressed in the equation, a linear function is obtained, and the following linear function (1-1) is obtained.
Cn = α (En) (1)
y = 1.544x-2.477 (1-1)
When the electric conductivity (En) (S / m) 6.194 at the initial concentration (Cn) of ammonium persulfate at 20 ° C. is substituted for x in the formula (1-1), the initial concentration (Cn) of ammonium persulfate at 20 ° C. (Mass%) was calculated to be 7.087 mass%.
次に、上記過硫酸アンモニウム溶液を５０℃にて数十時間放置し、液温２０℃における放置後の濃度（ｃｎ）と導電率（ｅｎ）の測定を、滴定により測定した。その結果を表３に示した。その結果、時間経過とともに過硫酸アンモニウムが分解して濃度が低下するに伴い、導電率が上昇する傾向のデータを得た。また、溶液によってその分解に対する導電率の変化が異なることが分かった。これは、同濃度の過硫酸アンモニウム溶液であっても、それと未分解の過硫酸アンモニウムと分解後の硫酸アンモニウムイオンとの共存溶液とでは、導電率の値が異なることを意味している。これはつまり、初期濃度によって、過硫酸アンモニウムの分解変化率（単一導電率変化当りの分解濃度の割合）が異なることを示している。
Next, the ammonium persulfate solution was allowed to stand at 50 ° C. for several tens of hours, and the concentration (cn) and conductivity (en) after standing at a liquid temperature of 20 ° C. were measured by titration. The results are shown in Table 3. As a result, data on the tendency of the conductivity to increase as ammonium persulfate decomposes over time and the concentration decreases was obtained. Moreover, it turned out that the change of the electric conductivity with respect to the decomposition | disassembly differs with solutions. This means that even in the case of an ammonium persulfate solution having the same concentration, the conductivity value is different between it and the coexisting solution of undecomposed ammonium persulfate and ammonium sulfate ions after decomposition. This indicates that the decomposition change rate of ammonium persulfate (the ratio of the decomposition concentration per single conductivity change) differs depending on the initial concentration.
表３より、液温２０℃における初期濃度の過硫酸アンモニウムの導電率（Ｅｎ）と放置後の過硫酸アンモニウムの導電率（ｅｎ）の変化量
（ΔＥｎ）と、初期濃度の過硫酸アンモニウム濃度（Ｃｎ）と放置後の過硫酸アンモニウムの濃度（ｃｎ）の変化量（ΔＣｎ）を計算し、これを表４に示した。図３は、表４のデータをプロットしたものである。即ち、図３における縦軸は、初期濃度の過硫酸アンモニウム濃度（Ｃｎ）と放置後の過硫酸アンモニウムの濃度（Ｃ）の変化量（ΔＣｎ）を表し、横軸は、液温２０℃における初期濃度の過硫酸アンモニウムの導電率（Ｅｎ）と放置後の過硫酸アンモニウムの導電率（ｅｎ）の変化量（ΔＥｎ）を表したものである。例えば、表４中の初期過硫酸アンモニウムの濃度が５質量％のときの放置後の濃度の変化量（低下ＡＰＳ濃度）（質量％）（ΔＣｎ）の０．１４６８は、表３中の５．０００−４．８５３２＝０．１４６８から求めたものであり、導電率の変化量（上昇導電率）（Ｓ／ｍ）（ΔＥｎ）の０．４４は、表３中の４．７６０−４．３２０＝０．４４００から求めたものである。同様にして、表４中のその他の値も表３から計算したものである。
その結果、導電率が上昇した場合、初期濃度が低いほど、分解する過硫酸アンモニウム濃度が低くなることが判明した。
From Table 3, the conductivity (En) of the initial concentration of ammonium persulfate at a liquid temperature of 20 ° C., the amount of change (ΔEn) in the conductivity (en) of the ammonium persulfate after standing, and the initial concentration of ammonium persulfate concentration (Cn) The amount of change (ΔCn) in the ammonium persulfate concentration (cn) after being allowed to stand was calculated and is shown in Table 4. FIG. 3 is a plot of the data in Table 4. That is, the vertical axis in FIG. 3 represents the initial concentration of ammonium persulfate (Cn) and the amount of change (ΔCn) in the ammonium persulfate concentration (C) after standing, and the horizontal axis represents the initial concentration at a liquid temperature of 20 ° C. It represents the amount of change (ΔEn) in the conductivity (En) of ammonium persulfate and the conductivity (en) of ammonium persulfate after standing. For example, when the initial ammonium persulfate concentration in Table 4 is 5% by mass, 0.1468 of the concentration change (decreased APS concentration) (% by mass) (ΔCn) after standing is 5.000 in Table 3. -4,532 = 0.1468, and the change amount of conductivity (increased conductivity) (S / m) (ΔEn) of 0.44 is 4.760-4.320 in Table 3. = 0.4400. Similarly, other values in Table 4 are also calculated from Table 3.
As a result, it was found that when the conductivity increased, the lower the initial concentration, the lower the ammonium persulfate concentration that decomposed.
以上の結果から、各濃度において導電率の上昇と過硫酸アンモニウム濃度の低下との関係は初期過硫酸アンモニウム２５質量％に於いて、相関係数Ｒ２＝０．９９９５以上の一次関数で示すことできる式であることが分かる。また、その単位導電率上昇変化あたりの過硫酸アンモニウム低下量の変化は、初期過硫酸アンモニウム濃度が高いほど大きいことが分かる。即ち初期濃度が低いほど単位導電率上昇あたりの過硫酸アンモニウムの分解も小さい。
図３から得られるグラフの各直線の近似式を求めると、表５となった。
From the above results, the relationship between the increase in conductivity and the decrease in ammonium persulfate concentration at each concentration is an equation that can be expressed by a linear function with a correlation coefficient R2 = 0.9995 or more at an initial ammonium persulfate concentration of 25% by mass. I understand that there is. Moreover, it turns out that the change of the ammonium persulfate fall amount per unit conductivity rise change is so large that an initial stage ammonium persulfate density | concentration is high. That is, the lower the initial concentration, the smaller the decomposition of ammonium persulfate per unit conductivity increase.
Table 5 shows the approximate expression of each straight line of the graph obtained from FIG.
表５の直線の傾きは、（Δ濃度）／（Δ導電率）、（ΔＣｎ）／（ΔＥｎ）であるので、この傾きである（Δ濃度）／（Δ導電率）、（ΔＣｎ）／（ΔＥｎ）と初期過硫酸アンモニウム濃度（Ｃｎ）をそれぞれピックアップしたものが表６の値となり、表６をグラフに表したものが図４となる。
Since the slopes of the straight lines in Table 5 are (Δconcentration) / (Δconductivity), (ΔCn) / (ΔEn), these slopes are (Δconcentration) / (Δconductivity), (ΔCn) / ( The values picked up for ΔEn) and the initial ammonium persulfate concentration (Cn) are the values in Table 6, and FIG. 4 is a graph showing Table 6 in FIG.
その結果、表６及び図４の関係式より、各濃度における単位導電率上昇あたりの濃度低下である、過硫酸塩溶液の分解変化率
（ΔＣｎ）／Δ（Ｅｎ）（（Δ濃度）／（Δ導電率））と初期濃度（Ｃｎ）との関係を示す関数である式
（ΔＣｎ）／（ΔＥｎ）＝β（Ｃｎ） （２）
は、次の指数関数である式（２−１）で表すことが出来ることが判明した。この式は、Ｒ２＝０．９２８５以上と良好な相関係数を得た。
ｙ＝０．２８０４ｘ0.3497 （２−１）
この導電率の上昇は、下記の化学式に示す通り、過硫酸塩が時間経過とともに硫酸イオンと水素イオンに分解していることを示唆していると考えられる。
2(NH4)+＋S2O8 2-＋2OH-＋2H+→2(NH4)+＋2SO4 2-＋2H+＋H2O2
次に、式（２−１）のｘに、過硫酸アンモニウムの初期濃度（Ｃｎ）（質量％）である、７．０８７質量％を代入すると、
ｙ＝０．２８０４×７．０８７0.3497＝０．５５６１
となり、サンプルの分解変化率（ΔＣｎ）／（ΔＥｎ）は、０．５５６１であることが計算された。
As a result, from the relational expressions in Table 6 and FIG. 4, the degradation change rate of the persulfate solution (ΔCn) / Δ (En) ((Δ concentration) / ( [Delta] conductivity)) and the function indicating the relationship between the initial concentration (Cn) (ΔCn) / (ΔEn) = β (Cn) (2)
Can be expressed by the following exponential function (2-1). This equation obtained a good correlation coefficient of R2 = 0.9285 or more.
y = 0.2804x 0.3497 (2-1)
This increase in conductivity is considered to suggest that persulfate is decomposed into sulfate ions and hydrogen ions over time as shown in the following chemical formula.
2 (NH 4) + + S 2 O 8 2- + 2OH - + 2H + → 2 (NH 4) + + 2SO 4 2- + 2H + + H 2 O 2
Next, when substituting 7.087 mass%, which is the initial concentration (Cn) (mass%) of ammonium persulfate, in x of the formula (2-1),
y = 0.2804 × 7.087 0.3497 = 0.5561
Thus, the decomposition change rate (ΔCn) / (ΔEn) of the sample was calculated to be 0.5561.
次に、放置した未知資料１の液温２８℃における導電率を測定したところ、７．９７９（Ｓ／ｍ）であり、図１を用いて、測定ポイントに最も近い式の傾きを採用し、（４−２）式よりｙ＝ａｘ＋ｂ式のａ（傾き）に０．１５００を代入し、上記導電率（ｙ）と液温（ｘ）の値とを代入し、測定サンプルの液温と導電率の関係を表す式が、
７．９７９＝０．１５００×２８＋ｂ、ｂ＝３．７７９となり、
ｙ＝０．１５００ｘ＋３．７７９となることが計算された。
上式を用いて、ｘ＝２０を代入すると、
ｙ＝０．１５００×２０＋３．７７９となり、測定したサンプルの２０℃における導電率が６．７７９（Ｓ／ｍ）であると計算された。
Next, when the conductivity of the left unknown material 1 at a liquid temperature of 28 ° C. was measured, it was 7.979 (S / m). Using FIG. 1, the slope of the equation closest to the measurement point was adopted, Substituting 0.1500 into a (slope) of y = ax + b equation from equation (4-2), substituting the above conductivity (y) and liquid temperature (x) values, and measuring the liquid temperature and conductivity of the measurement sample. The expression that expresses the relationship between rates is
7.979 = 0.1500 × 28 + b, b = 3.779,
It was calculated that y = 0.1500x + 3.779.
Using the above equation, substituting x = 20,
y = 0.1500 × 20 + 3.779, and the measured conductivity of the sample at 20 ° C. was calculated to be 6.779 (S / m).
前記工程により求められた、前記溶解直後の過硫酸塩溶液の初期濃度（Ｃｎ）における導電率（Ｅｎ）と薬液供給時の過硫酸塩溶液の導電率（ｅｎ）の導電率変化（ΔＥｎ）は、
（ΔＥｎ）＝（ｅｎ）−（Ｅｎ） （５）
と、初期濃度（Ｃｎ）、過硫酸塩溶液の分解変化率（ΔＣｎ）／（ΔＥｎ）との関係から、薬液供給時の濃度Ｃ（残存する過硫酸塩の濃度）を示す関数は、残存する過硫酸塩の濃度＝（初期濃度）−（分解変化率）×（導電率変化）となる。ここで、過硫酸塩溶液の分解変化率とは、単位導電率変化当たりの過硫酸アンモニウムの分解変化率（ΔＣｎ）／（ΔＥｎ）であり、導電率変化（ΔＥｎ）とは、ΔＥｎ＝（ｅｎ）−（Ｅｎ）となり、薬液供給時の濃度Ｃ（残存する過硫酸塩の濃度）を示す上記関数は、式（３）で表すことができる。
（Ｃ）＝（Ｃｎ）−｛（ΔＣｎ）／（ΔＥｎ）｝×（ΔＥｎ） （３）
また、式（３）に、初期濃度、（Ｃｎ）＝７．０８７、分解変化率、
（ΔＣｎ）／（ΔＥｎ）＝０．５５６１、（ΔＥｎ）＝（ｅｎ）−（Ｅｎ）＝６．７７９−６．１９４を代入すると、
ｙ＝７．０８７−０．５５６１×（６．７７９−６．１９４）＝６．７６５となり、２０℃における初期導電率６．７７９（Ｓ／ｍ）となる過硫酸アンモニウムの濃度は、６．７６５質量％であることが計算された。
実際に滴定により、濃度を測定したところ６．７３７質量％であり、計算値と実測値との差異は０．０２８００質量％であった。
The electrical conductivity change (ΔEn) of the electrical conductivity (En) at the initial concentration (Cn) of the persulfate solution immediately after dissolution and the electrical conductivity (en) of the persulfate solution at the time of supplying the chemical solution obtained by the above step is ,
(ΔEn) = (en) − (En) (5)
From the relationship between the initial concentration (Cn) and the decomposition change rate of the persulfate solution (ΔCn) / (ΔEn), a function indicating the concentration C (concentration of the remaining persulfate) at the time of supplying the chemical solution remains. Persulfate concentration = (initial concentration) − (decomposition change rate) × (conductivity change). Here, the decomposition change rate of the persulfate solution is the decomposition change rate (ΔCn) / (ΔEn) of ammonium persulfate per unit conductivity change, and the conductivity change (ΔEn) is ΔEn = (en) -(En), and the above function indicating the concentration C (concentration of the remaining persulfate) at the time of supplying the chemical solution can be expressed by the equation (3).
(C) = (Cn) − {(ΔCn) / (ΔEn)} × (ΔEn) (3)
In addition, the initial concentration, (Cn) = 7.087, the decomposition change rate,
Substituting (ΔCn) / (ΔEn) = 0.5561, (ΔEn) = (en) − (En) = 6.779-6.194,
y = 7.087−0.5561 × (6.779−6.194) = 6.765, and the concentration of ammonium persulfate at which the initial conductivity at 20 ° C. is 6.779 (S / m) is 6.765. It was calculated to be mass%.
When the concentration was actually measured by titration, it was 6.737% by mass, and the difference between the calculated value and the actually measured value was 0.02800% by mass.
＜実施例２−３＞
同様に未知資料２、３の、溶解直後の導電率の測定後、放置後の導電率から求めた値と実測値を比較した。
<Example 2-3>
Similarly, after measuring the electrical conductivity of the unknown materials 2 and 3 immediately after dissolution, the value obtained from the electrical conductivity after standing was compared with the actual measurement value.
その結果、式（３）から求めた、過硫酸アンモニウムの劣化濃度、即ち、液供給時の過硫酸アンモニウムの濃度は、表７に示すとおり、
ｙ＝１６．４２質量％であり、計算値と実測値との差異は０．２５００質量％であった。
As a result, the deterioration concentration of ammonium persulfate obtained from the formula (3), that is, the concentration of ammonium persulfate at the time of supplying the liquid, as shown in Table 7,
y = 16.42% by mass, and the difference between the calculated value and the actually measured value was 0.2500% by mass.
その結果、式（３）から求めた、過硫酸アンモニウムの劣化濃度、即ち、液供給時の過硫酸アンモニウムの濃度は、表８に示すとおり、
ｙ＝２５．０６質量％であり、計算値と実測値との差異は０．１６００質量％であった。
As a result, the deterioration concentration of ammonium persulfate obtained from the formula (3), that is, the concentration of ammonium persulfate at the time of supplying the liquid, as shown in Table 8,
y = 25.06 mass%, and the difference between the calculated value and the actually measured value was 0.1600 mass%.
以上のように３種類の未知資料においての式１）、式２）、式３）および式４）から求めた値と滴定にて求めたそれぞれの実測値は、ほぼ同等の値であり、本方法による過硫酸アンモニウム濃度のモニタリングは可能且つ良好であることが実証された。 As described above, the values obtained from Equation 1), Equation 2), Equation 3) and Equation 4) for the three types of unknown materials and the actual values obtained by titration are almost equivalent values. Monitoring of ammonium persulfate concentration by the method has proven to be possible and good.
本発明は、粉末または固形物の過硫酸塩を溶媒に溶解して所望濃度の過硫酸溶液として、スラリーを使用する化学機械的研磨工程に供給する薬液供給装置であって、溶解後に導電率を測定することによって過硫酸塩の成分分濃度を求め、その後導電率変化を計測することによって過硫酸塩の分解率を捉えることにより、分解後の有効過硫酸塩成分の濃度を計算して、酸化力の低下を管理することができる。 The present invention relates to a chemical supply apparatus for dissolving a powder or solid persulfate in a solvent and supplying it to a chemical mechanical polishing process using a slurry as a persulfuric acid solution having a desired concentration. The concentration of persulfate component is obtained by measuring, and then the persulfate decomposition rate is measured by measuring the change in conductivity. Can manage power decline.
Claims (3)
粉末または固形物の過硫酸アンモニウムに溶媒を加えて溶解して、５質量％以下毎の幅で低濃度から高濃度に亘り各種濃度の過硫酸アンモニウム溶液を作成し、任意の温度における溶解直後の各種濃度の過硫酸アンモニウム溶液の初期濃度（Ｃｎ）の導電率（Ｅｎ）を測定する工程と、
前記任意の温度における溶解直後の各種濃度の過硫酸アンモニウム溶液の導電率（Ｅｎ）と前記任意の温度における溶解直後の過硫酸アンモニウム溶液の初期濃度（Ｃｎ）との関係を示す一次関数である式（１−１）を予め作成する工程と、
式（１−１）より、前記任意の温度における溶解直後の各種濃度の過硫酸アンモニウム溶液の導電率（Ｅｎ）における過硫酸アンモニウム溶液の初期濃度（Ｃｎ）を算出する工程と、
前記任意の温度における薬液供給時の過硫酸アンモニウム溶液の導電率（ｅｎ）を測定する工程と、
式（５）より、前記溶解直後における過硫酸アンモニウム溶液の初期濃度（Ｃｎ）における導電率（Ｅｎ）と薬液供給時の過硫酸アンモニウム溶液の導電率（ｅｎ）との導電率変化量である（ΔＥｎ）を算出する工程と、
前記任意の温度における溶解直後の各種濃度の過硫酸アンモニウム溶液の初期濃度（Ｃｎ）と薬液供給時の分解変化率（ΔＣｎ）／（ΔＥｎ）との関係を示す指数関数である式（２−１）を予め作成する工程（ただし、（ΔＣｎ）は、溶解直後における過硫酸塩溶液の初期濃度と薬液供給時の濃度との変化量である）と、
式（２−１）より、前記任意の温度における溶解直後の各種濃度の過硫酸アンモニウム溶液の初期濃度（Ｃｎ）における薬液供給時の分解変化率（ΔＣｎ）／（ΔＥｎ）を算出する工程と、
前記工程により測定及び算出した、前記溶解直後の過硫酸アンモニウム溶液の初期濃度（Ｃｎ）と、薬液供給時の過硫酸アンモニウム溶液の分解変化率（ΔＣｎ）／（ΔＥｎ）と、前記薬液供給時の過硫酸アンモニウム溶液の導電率の変化量（ΔＥｎ）とを式（３）に代入し、薬液供給時の過硫酸アンモニウム溶液の濃度（残存する過硫酸塩の濃度）（Ｃ）を求める工程とよりなることを特徴とする薬液供給方法。
（Ｃｎ）＝ａ（Ｅｎ）＋ｂ （１−１）
（式（１−１）は、一次関数であり、ａ、ｂは、実験により求めた定数である）
（ΔＥｎ）＝（ｅｎ）−（Ｅｎ） （５）
（ΔＣｎ）／（ΔＥｎ）＝ｃ（Ｃｎ）d （２−１）
（式（２−１）は、指数関数であり、ｃ、ｄは、実験により求めた定数である）
（Ｃ）＝（Ｃｎ）−｛（ΔＣｎ）／（ΔＥｎ）｝×（ΔＥｎ） （３） In the chemical solution supplying method for supplying the chemical solution containing ammonium persulfate to the chemical mechanical polishing step,
Was dissolved in ammonium persulfate by addition of solvent of powders or solids, 5% by mass of ammonium persulfate solutions of various concentrations were prepared over a high concentration from a low concentration range of each following, immediately after dissolution at any temperature various Measuring the conductivity (En) of the initial concentration (Cn) of the ammonium persulfate solution at a concentration;
Equation (1) which is a linear function showing the relationship between the conductivity (En) of the ammonium persulfate solution at various concentrations immediately after dissolution at the arbitrary temperature and the initial concentration (Cn) of the ammonium persulfate solution immediately after dissolution at the arbitrary temperature. -1) in advance,
From the equation (1-1), calculating the initial concentration (Cn) of the ammonium persulfate solution in the conductivity (En) of the ammonium persulfate solution of various concentrations immediately after dissolution at the arbitrary temperature;
Measuring the conductivity (en) of the ammonium persulfate solution when supplying the chemical solution at the arbitrary temperature;
From Equation (5), the change in conductivity between the conductivity (En) at the initial concentration (Cn) of the ammonium persulfate solution immediately after dissolution and the conductivity (en) of the ammonium persulfate solution at the time of supplying the chemical solution (ΔEn) Calculating
Formula (2-1) which is an exponential function showing the relationship between the initial concentration (Cn) of ammonium persulfate solution of various concentrations immediately after dissolution at the arbitrary temperature and the rate of change in decomposition (ΔCn) / (ΔEn) during chemical supply (Where (ΔCn) is the amount of change between the initial concentration of the persulfate solution immediately after dissolution and the concentration at the time of supplying the chemical solution),
From the equation (2-1), a step of calculating a decomposition change rate (ΔCn) / (ΔEn) at the time of supplying a chemical solution at an initial concentration (Cn) of an ammonium persulfate solution having various concentrations immediately after dissolution at the arbitrary temperature;
The initial concentration (Cn) of the ammonium persulfate solution immediately after dissolution, the decomposition change rate (ΔCn) / (ΔEn) of the ammonium persulfate solution at the time of supplying the chemical solution, and the ammonium persulfate at the time of supplying the chemical solution, which are measured and calculated by the above steps Substituting the amount of change in electrical conductivity of the solution (ΔEn) into the equation (3) to obtain the concentration of ammonium persulfate solution (concentration of remaining persulfate) (C) when supplying the chemical solution. The chemical solution supply method.
(Cn) = a (En) + b (1-1)
(Formula (1-1) is a linear function, and a and b are constants obtained by experiments)
(ΔEn) = (en) − (En) (5)
(ΔCn) / (ΔEn) = c (Cn) d (2-1)
(Formula (2-1) is an exponential function, and c and d are constants obtained by experiments)
(C) = (Cn) − {(ΔCn) / (ΔEn)} × (ΔEn) (3)
粉末または固形物の過硫酸アンモニウムに溶媒を加えて溶解して、５質量％以下毎の幅で低濃度から高濃度に亘り作成された各種濃度の過硫酸アンモニウム溶液を用いて、任意の温度における溶解直後の各種濃度の過硫酸アンモニウム溶液の初期濃度（Ｃｎ）の導電率（Ｅｎ）を測定する工程と、
前記任意の温度における溶解直後の各種濃度の過硫酸アンモニウム溶液の導電率（Ｅｎ）と前記任意の温度における溶解直後の過硫酸アンモニウム溶液の初期濃度（Ｃｎ）との関係を示す一次関数である式（１−１）を予め作成する工程と、
式（１−１）より、前記任意の温度における溶解直後の各種濃度の過硫酸アンモニウム溶液の導電率（Ｅｎ）における過硫酸アンモニウム溶液の初期濃度（Ｃｎ）を算出する工程と、
前記任意の温度における薬液供給時の過硫酸アンモニウム溶液の導電率（ｅｎ）を測定する工程と、
式（２−１）より、前記溶解直後における過硫酸アンモニウム溶液の初期濃度（Ｃｎ）における導電率（Ｅｎ）と薬液供給時の過硫酸アンモニウム溶液の導電率（ｅｎ）との導電率変化量である（ΔＥｎ）を算出する工程と、
前記任意の温度における溶解直後の各種濃度の過硫酸アンモニウム溶液の初期濃度（Ｃｎ）と薬液供給時の分解変化率（ΔＣｎ）／（ΔＥｎ）との関係を示す指数関数である式（２−１）を予め作成する工程（ただし、（ΔＣｎ）は、溶解直後における過硫酸アンモニウム溶液の初期濃度と薬液供給時の濃度との変化量である）と、
式（３）より、前記任意の温度における溶解直後の各種濃度の過硫酸アンモニウム溶液の初期濃度（Ｃｎ）における薬液供給時の分解変化率（ΔＣｎ）／（ΔＥｎ）を算出する工程と、
前記工程により測定及び算出した、前記溶解直後の過硫酸アンモニウム溶液の初期濃度（Ｃｎ）と、薬液供給時の過硫酸アンモニウム溶液の分解変化率
（ΔＣｎ）／（ΔＥｎ）と、前記薬液供給時の過硫酸アンモニウム溶液の導電率の変化量（ΔＥｎ）とを式（３）に代入し、薬液供給時の過硫酸アンモニウム溶液の濃度（残存する過硫酸アンモニウムの濃度）（Ｃ）を求める工程とよりなる機構を備えたことを特徴とする薬液供給装置。
（Ｃｎ）＝ａ（Ｅｎ）＋ｂ （１−１）
（式（１−１）は、一次関数であり、ａ、ｂは、実験により求めた定数である）
（ΔＥｎ）＝（ｅｎ）−（Ｅｎ） （５）
（ΔＣｎ）／（ΔＥｎ）＝ｃ（Ｃｎ）d （２−１）
（式（２−１）は、指数関数であり、ｃ、ｄは、実験により求めた定数である）
（Ｃ）＝（Ｃｎ）−｛（ΔＣｎ）／（ΔＥｎ）｝×（ΔＥｎ） （３） In the chemical solution supply apparatus for supplying a chemical solution containing ammonium persulfate to the chemical mechanical polishing process,
It was dissolved in ammonium persulfate by addition of solvent of powder or solid, with ammonium persulfate solution created various concentrations over the high concentration from a low concentration range of each under 5% by mass or, dissolution at any temperature Measuring the conductivity (En) of the initial concentration (Cn) of the ammonium persulfate solution of various concentrations immediately after;
Equation (1) which is a linear function showing the relationship between the conductivity (En) of the ammonium persulfate solution at various concentrations immediately after dissolution at the arbitrary temperature and the initial concentration (Cn) of the ammonium persulfate solution immediately after dissolution at the arbitrary temperature. -1) in advance,
From the equation (1-1), calculating the initial concentration (Cn) of the ammonium persulfate solution in the conductivity (En) of the ammonium persulfate solution of various concentrations immediately after dissolution at the arbitrary temperature;
Measuring the conductivity (en) of the ammonium persulfate solution when supplying the chemical solution at the arbitrary temperature;
From the formula (2-1), the change in conductivity between the conductivity (En) at the initial concentration (Cn) of the ammonium persulfate solution immediately after the dissolution and the conductivity (en) of the ammonium persulfate solution at the time of supplying the chemical solution ( Calculating ΔEn);
Formula (2-1) which is an exponential function showing the relationship between the initial concentration (Cn) of ammonium persulfate solution of various concentrations immediately after dissolution at the arbitrary temperature and the rate of change in decomposition (ΔCn) / (ΔEn) during chemical supply (Where (ΔCn) is the amount of change between the initial concentration of the ammonium persulfate solution immediately after dissolution and the concentration at the time of supplying the chemical solution),
From Equation (3), a step of calculating a decomposition change rate (ΔCn) / (ΔEn) at the time of supplying a chemical solution at an initial concentration (Cn) of an ammonium persulfate solution having various concentrations immediately after dissolution at the arbitrary temperature;
The initial concentration (Cn) of the ammonium persulfate solution immediately after dissolution, the decomposition change rate (ΔCn) / (ΔEn) of the ammonium persulfate solution at the time of supplying the chemical solution, and the ammonium persulfate at the time of supplying the chemical solution, which are measured and calculated by the above steps Substituting the amount of change in electrical conductivity of the solution (ΔEn) into equation (3) to obtain the concentration of ammonium persulfate solution (concentration of remaining ammonium persulfate) (C) when supplying the chemical solution, and a mechanism comprising A chemical supply apparatus characterized by the above.
(Cn) = a (En) + b (1-1)
(Formula (1-1) is a linear function, and a and b are constants obtained by experiments)
(ΔEn) = (en) − (En) (5)
(ΔCn) / (ΔEn) = c (Cn) d (2-1)
(Formula (2-1) is an exponential function, and c and d are constants obtained by experiments)
(C) = (Cn) − {(ΔCn) / (ΔEn)} × (ΔEn) (3)
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