JP7303662B2 - Method for analyzing metal impurities on the surface of polycrystalline silicon chunks - Google Patents

Method for analyzing metal impurities on the surface of polycrystalline silicon chunks Download PDF

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JP7303662B2
JP7303662B2 JP2019090014A JP2019090014A JP7303662B2 JP 7303662 B2 JP7303662 B2 JP 7303662B2 JP 2019090014 A JP2019090014 A JP 2019090014A JP 2019090014 A JP2019090014 A JP 2019090014A JP 7303662 B2 JP7303662 B2 JP 7303662B2
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モハマッド・ビー・シャバニー
賢一 富岡
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高純度シリコン株式会社
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Description

本発明は、多結晶シリコン塊の表面に存在する金属不純物を分析する方法に関する。更に詳しくは、誘導結合プラズマ質量分析(以下、ICP-MSということもある。)法により多結晶シリコン塊表面の金属不純物を分析する方法に関するものである。 The present invention relates to a method of analyzing metal impurities existing on the surface of a polycrystalline silicon mass. More specifically, the present invention relates to a method of analyzing metal impurities on the surface of a polycrystalline silicon chunk by inductively coupled plasma mass spectrometry (hereinafter also referred to as ICP-MS).

従来、この種の金属不純物分析方法では、例えば、先ず、多結晶シリコン塊をエッチングするための処理容器に、多結晶シリコン塊のサンプルとこのサンプルが十分浸漬するだけの硝酸とフッ化水素酸の混酸に代表されるエッチング液を入れてサンプル表層をエッチングして、サンプル表面に存在する金属不純物をエッチング液中に含ませていた。次に、金属不純物を含んだエッチング液を処理容器から回収した後、回収液を濃縮乾固し、得られた乾固物を少量の酸で溶解後、原子吸光分析法や誘導結合プラズマ質量分析法等を用いて分析していた。 Conventionally, in this type of metal impurity analysis method, for example, first, a sample of a polycrystalline silicon lump is placed in a processing vessel for etching the polycrystalline silicon lump, and nitric acid and hydrofluoric acid are added so that the sample is sufficiently immersed. An etchant represented by a mixed acid was added to etch the surface of the sample, so that metal impurities present on the surface of the sample were included in the etchant. Next, after recovering the etchant containing metal impurities from the processing container, the recovered solution is concentrated to dryness, and after dissolving the obtained dry matter with a small amount of acid, atomic absorption spectrometry or inductively coupled plasma mass spectrometry is performed. It was analyzed using the law, etc.

しかし、このような分析方法ではサンプルをエッチング液中に十分浸漬させるためには多量のエッチング液を使用する必要があり、分析の感度を上げるために濃縮乾固して分析を行うが、濃縮を伴う分析方法ではエッチング液中にもとから金属不純物が含まれているため、多量のエッチング液では定量分析の際にブランク値が高くなる問題があり、また多量のエッチング液を濃縮させるのに多大の時間を要するという問題があった。 However, in this kind of analysis method, it is necessary to use a large amount of etching solution in order to fully immerse the sample in the etching solution. In the accompanying analysis method, the etching solution originally contains metal impurities, so there is a problem that a large amount of the etching solution results in a high blank value during quantitative analysis. There was a problem that it takes time for

このような上記諸問題を解決する方策として、円筒状の密閉した処理容器内に、多結晶シリコン試料とこの多結晶シリコン試料が一部浸漬する程度の少量のエッチング液とを収納した後、処理容器にローラーシェイカーによる回転運動のような動きを与えることにより多結晶シリコン表面にエッチング液を接触させて、処理容器からエッチング液を回収し、この回収されたエッチング液について分析を行う多結晶シリコン表層部不純物の分析方法が開示されている(例えば、特許文献1(請求項1、段落[0007]、段落[0010]、段落[0014]、段落[0031]~段落[0036]、図1、図2)参照。)。特許文献1には、エッチング液としては、フッ化水素酸と硝酸との混酸の場合、フッ化水素酸10~20質量%、硝酸30~50質量%が好ましい旨が記載されている。 As a measure to solve the above-mentioned problems, a polycrystalline silicon sample and a small amount of etchant such that the polycrystalline silicon sample is partially immersed are placed in a sealed cylindrical processing vessel, and then processed. The etchant is brought into contact with the surface of the polycrystalline silicon by giving the container a motion similar to the rotational motion of a roller shaker, the etchant is recovered from the processing container, and the recovered etchant is analyzed. (For example, Patent Document 1 (claim 1, paragraph [0007], paragraph [0010], paragraph [0014], paragraph [0031] to paragraph [0036], Figure 1, Figure 2) See.). Patent Document 1 describes that, in the case of a mixed acid of hydrofluoric acid and nitric acid, 10 to 20% by mass of hydrofluoric acid and 30 to 50% by mass of nitric acid are preferable as an etchant.

この特許文献1には、この方法によれば、試料とともに収納するエッチング液量が従来の量より遙かに少ない場合でも、均一にその表面をエッチングすることが可能であり、その後エッチング液を必要に応じて濃縮する場合でも、試料処理におけるエッチング液由来の不純物量を著しく減少できる旨が記載されている。 According to this patent document 1, according to this method, even if the amount of etchant contained together with the sample is much smaller than the conventional amount, it is possible to uniformly etch the surface, and after that, the etchant is required. It is described that the amount of impurities derived from the etchant in sample processing can be remarkably reduced even when the sample is concentrated according to the conditions.

特開2000-266650号公報JP-A-2000-266650

しかしながら、上記特許文献1に示される方法では、試料を処理するための専用の処理容器と回転運動を与えるローラーシェイカーのような装置を必要とする不具合があった。また処理容器に多結晶シリコン試料と少量のエッチング液を入れて蓋をして格納し、処理容器を密閉状態で回転させた後、処理容器の蓋を外して、処理容器からエッチング液を取り出すため、分析用試料(サンプル)の作製が迅速にできない課題があった。また処理容器の回転運動により、容器内部の塊状の多結晶シリコン試料が破損することがあり、またフッ化水素酸10~20質量%と硝酸30~50質量%という濃度の高い混酸からなるエッチング液が多結晶シリコン試料に繰り返し接触するため、多量のエッチング液を用いる上記従来の方法と同様に、エッチング液中にシリコンマトリックスが溶解するとともに、酸からの汚染を低減できなかった。 However, the method disclosed in Patent Literature 1 has the drawback of requiring a dedicated processing vessel for processing the sample and a device such as a roller shaker that imparts rotational motion. Also, a polycrystalline silicon sample and a small amount of etchant are placed in a processing container, the lid is closed, and the processing container is rotated. , there was a problem that the sample for analysis could not be prepared quickly. In addition, due to the rotating motion of the processing container, the block polycrystalline silicon sample inside the container may be damaged. is repeatedly in contact with the polycrystalline silicon sample, the silicon matrix dissolves in the etchant and contamination from the acid cannot be reduced, as in the conventional method using a large amount of etchant.

このため、上記特許文献1に示される方法では、分析用サンプルを分析装置に導入する前に、上記従来の方法と同様に、長い時間をかけて分析用サンプルからシリコンマトリックスを揮散分離させる必要があった。この揮散分離に要する時間が長いため、ホットプレート等のクリーンルーム環境からの汚染、オペレーターが接触する際の汚染、更には加熱されたビーカーからの汚染が発生していた。また、上記揮散分離が進行して、分析用サンプルの液が蒸発して完全になくなった時にビーカー底部に分析しようとする元素が固着していた。この固着した元素は、最終分析に用いる酸では完全に回収されず、このためサンプルを正確に分析することができなかった。また、揮散分離の乾固時に、B、P、As等の元素がフッ化物錯体を形成するため、低温で蒸発して失われてしまい、高精度な分析をすることが困難であった。 Therefore, in the method disclosed in Patent Document 1, it is necessary to volatilize and separate the silicon matrix from the sample for analysis over a long period of time before introducing the sample for analysis into the analyzer, as in the conventional method. there were. Because of the long time required for this volatilization separation, contamination from the clean room environment such as a hot plate, contamination during operator contact, and further contamination from a heated beaker occurred. In addition, when the volatilization and separation proceeded and the analysis sample liquid evaporated and completely disappeared, the element to be analyzed adhered to the bottom of the beaker. This stuck element was not completely recovered in the acid used for the final analysis, which prevented accurate analysis of the sample. In addition, since elements such as B, P, and As form fluoride complexes during evaporation and separation to dryness, they evaporate at low temperatures and are lost, making it difficult to perform highly accurate analysis.

シリコン中のB(ボロン)及びP(リン)が存在すると、このシリコンを用いて作られた半導体デバイスの品質に極めて悪影響を及ぼす。また極微量のアルカリ金属、アルカリ土類金属及び遷移金属の不純物がシリコンチップ素子に存在すると、電圧破壊又は高い暗電流が生じたり、少数キャリアの劣化などが起きて、これらのシリコンチップ素子を用いたシリコン系半導体デバイスの品質に極めて悪影響を及ぼす。このため、多結晶シリコン塊中に存在する極微量の金属不純物を定量分析することは重要である。 The presence of B (boron) and P (phosphorus) in silicon has a very detrimental effect on the quality of semiconductor devices made with this silicon. In addition, if trace amounts of impurities such as alkali metals, alkaline earth metals, and transition metals are present in silicon chip elements, voltage breakdown or high dark current may occur, or deterioration of minority carriers may occur. It has a very bad influence on the quality of the silicon-based semiconductor device. For this reason, it is important to quantitatively analyze trace amounts of metal impurities present in polycrystalline silicon masses.

本発明の目的は、定量分析用の酸の量を減らして、酸からの汚染を低減するとともに、シリコンマトリックスの溶解量を削減し、分析用サンプルを迅速に作製して、多結晶シリコン塊表面のB、P、As等の金属不純物を高感度に定量分析し得る多結晶シリコン塊表面の金属不純物分析方法を提供することにある。 An object of the present invention is to reduce the amount of acid for quantitative analysis, reduce contamination from the acid, reduce the amount of dissolution of the silicon matrix, quickly prepare a sample for analysis, and make the surface of the polycrystalline silicon mass The object of the present invention is to provide a method for analyzing metal impurities on the surface of a polycrystalline silicon lump surface, which can quantitatively analyze metal impurities such as B, P, As, etc., with high sensitivity.

本発明の第1の観点の多結晶シリコン塊表面の金属不純物分析方法は、多結晶シリコン塊の質量(W)(単位:g)を測定し、前記多結晶シリコン塊を上部が開口した容器に収納し、硝酸とフッ化水素酸と過酸化水素水との混合溶液を、前記多結晶シリコン塊の質量(W)に対する前記混合溶液の容量(V)(単位:ml)の割合(V/W)(単位:g/ml)が10%~20%になるように、前記容器内の多結晶シリコン塊の上からマイクロピペットにより滴下して前記多結晶シリコン塊の表面に前記混合溶液の自重で前記混合溶液を行き渡らせた後、前記多結晶シリコン塊の表面から前記混合溶液の自重で流下して前記容器底部に溜まった液を前記容器の上方から前記容器底部に挿入したマイクロピペットにより採取して、採取した液を分析用サンプルとして、誘導結合プラズマ質量分析装置に直接導入することにより、前記採取液に含まれるP(リン)、B(ボロン)、As(ヒ素)及びそれら以外の金属からなる群より選ばれた1種又は2種以上の金属不純物を誘導結合プラズマ質量分析法により定量分析する方法である。 In the method for analyzing metal impurities on the surface of a polycrystalline silicon lump according to the first aspect of the present invention, the mass (W) (unit: g) of the polycrystalline silicon lump is measured, and the polycrystalline silicon lump is placed in a container with an open top. A mixed solution of nitric acid, hydrofluoric acid and hydrogen peroxide solution is divided into a ratio (V/W) of the volume (V) (unit: ml) of the mixed solution to the mass (W) of the polycrystalline silicon lump. ) (unit: g/ml) of 10% to 20%, the mixed solution is dropped from above the polycrystalline silicon lump in the container with a micropipette to the surface of the polycrystalline silicon lump with its own weight of the mixed solution. After spreading the mixed solution, the mixed solution flowed down from the surface of the polycrystalline silicon mass under its own weight and collected at the bottom of the container was collected with a micropipette inserted into the bottom of the container from above. Then , by directly introducing the collected liquid as an analysis sample into an inductively coupled plasma mass spectrometer, P (phosphorus), B (boron), As (arsenic) and other metals contained in the collected liquid It is a method of quantitatively analyzing one or more metal impurities selected from the group consisting of by inductively coupled plasma mass spectrometry.

本発明の第2の観点の多結晶シリコン塊表面の金属不純物分析方法では、前記混合溶液は、濃度1質量%~5質量%の硝酸と、濃度1質量%~5質量%のフッ化水素酸と、濃度1質量%~3質量%の過酸化水素水との混合溶液である。 In the method for analyzing metal impurities on the surface of polycrystalline silicon chunks according to the second aspect of the present invention, the mixed solution comprises nitric acid having a concentration of 1% to 5% by mass and hydrofluoric acid having a concentration of 1% to 5% by mass. and a hydrogen peroxide solution with a concentration of 1% by mass to 3% by mass.

本発明の第3の観点の多結晶シリコン塊表面の金属不純物分析方法では、前記容器に収納する多結晶シリコン塊の質量(W)が40g~80gである。 In the method for analyzing metal impurities on the surface of polycrystalline silicon chunks according to the third aspect of the present invention, the mass (W) of the polycrystalline silicon chunks housed in the container is 40 g to 80 g.

本発明の第4の観点の多結晶シリコン塊表面の金属不純物分析方法では、前記P、B、As以外の金属がLi、Na、Mg、Al、K、Ca、Cr、Mn、Fe、Ni、Co、Cu、Zn、Sr、Mo、Cd、Ba及びPbからなる群より選ばれた1種又は2種以上の金属である。 In the method for analyzing metal impurities on the surface of a polycrystalline silicon lump according to the fourth aspect of the present invention, the metals other than P, B and As are Li, Na, Mg, Al, K, Ca, Cr, Mn, Fe, Ni, One or more metals selected from the group consisting of Co, Cu, Zn, Sr, Mo, Cd, Ba and Pb.

本発明の第1の観点の多結晶シリコン塊表面の金属不純物分析方法では、多結晶シリコン塊の質量(W)(単位:g)に対して混合溶液の容量(V)(単位:ml)を10%~20%の非常に少ない割合(V/W)(単位:g/ml)で容器内の多結晶シリコン塊の上からマイクロピペットにより滴下して多結晶シリコン塊の表面に混合溶液の自重で混合溶液を行き渡らせた後、多結晶シリコン塊の表面から前記混合溶液の自重で流下して容器底部に溜まった液を容器の上方から前記容器底部に挿入したマイクロピペットにより採取して、採取した液をICP-MS法の分析用サンプルとしてICP-MS装置に直接導入する。このため、定量分析用の酸の量を減らして、酸からの汚染を低減するとともに、シリコンマトリックスの溶解量を削減することができる。また分析用サンプルを迅速に作製することができる。更にICP-MS法により多結晶シリコン塊表面のB、P、As等の金属不純物を高感度に定量分析することができる。

In the method for analyzing metal impurities on the surface of a polycrystalline silicon chunk according to the first aspect of the present invention, the volume (V) (unit: ml) of the mixed solution is calculated with respect to the mass (W) (unit: g) of the polycrystalline silicon chunk. A very small ratio (V/W) of 10% to 20% (unit: g/ml) is dropped from the top of the polycrystalline silicon mass in the container with a micropipette, and the weight of the mixed solution is applied to the surface of the polycrystalline silicon mass. After spreading the mixed solution in , collect the liquid accumulated at the bottom of the container by flowing down from the surface of the polycrystalline silicon block by the weight of the mixed solution by a micropipette inserted from above the container into the bottom of the container. The resulting liquid is directly introduced into the ICP-MS apparatus as a sample for analysis in the ICP-MS method. Therefore, the amount of acid for quantitative analysis can be reduced to reduce contamination from the acid and reduce the dissolution amount of the silicon matrix. Also, samples for analysis can be prepared quickly. Furthermore, by the ICP-MS method, metal impurities such as B, P and As on the surface of the polycrystalline silicon mass can be quantitatively analyzed with high sensitivity.

本発明の第2の観点の多結晶シリコン塊表面の金属不純物分析方法では、前記混合溶液は、濃度1質量%~5質量%の硝酸と、濃度1質量%~5質量%のフッ化水素酸と、濃度1質量%~3質量%の過酸化水素水との混合溶液であるため、金属不純物との反応性、塊表面に存在する二酸化シリコンのエッチング性及び塊表面において金属堆積(plating)を形成する金属の除去性により優れる。またV/Wの割合が小さいことに加えて、特許文献1に示される混酸よりも濃度の低い硝酸及びフッ化水素酸を用いるため、より一層酸からの汚染を低減することができる。 In the method for analyzing metal impurities on the surface of polycrystalline silicon chunks according to the second aspect of the present invention, the mixed solution comprises nitric acid having a concentration of 1% to 5% by mass and hydrofluoric acid having a concentration of 1% to 5% by mass. and a hydrogen peroxide solution with a concentration of 1% by mass to 3% by mass. Better removability of the formed metal. In addition to the small V/W ratio, nitric acid and hydrofluoric acid having concentrations lower than those of the mixed acid disclosed in Patent Document 1 are used, so contamination from acids can be further reduced.

本発明の第3の観点の多結晶シリコン塊表面の金属不純物分析方法では、容器に収納する多結晶シリコン塊の質量(W)が40g~80gという少量であって、V/Wが10%~20%であるため、用いる混合溶液の量を減らして、分析用サンプルを作製するためのコストを低減することができる。 In the method for analyzing metal impurities on the surface of a polycrystalline silicon lump according to the third aspect of the present invention, the mass (W) of the polycrystalline silicon lump contained in the container is as small as 40 g to 80 g, and the V/W is 10% to 10%. Since it is 20%, it is possible to reduce the amount of the mixed solution used and reduce the cost for preparing the sample for analysis.

本発明の第4の観点の多結晶シリコン塊表面の金属不純物分析方法では、酸からの汚染の低減とシリコンマトリックスの溶解量の削減から、ICP-MS法により、数多くの金属の定量分析を行うことができる。 In the method for analyzing metal impurities on the surface of polycrystalline silicon chunks according to the fourth aspect of the present invention, quantitative analysis of many metals is performed by the ICP-MS method because of the reduction of acid contamination and the reduction of the amount of dissolution of the silicon matrix. be able to.

図1は、本発明の実施形態に係る多結晶シリコン塊表面の金属不純物を分析する方法の工程図である。FIG. 1 is a process diagram of a method for analyzing metal impurities on the surface of a polycrystalline silicon chunk according to an embodiment of the present invention.

次に本発明を実施するための形態について図面を参照して説明する。 Next, a mode for carrying out the present invention will be described with reference to the drawings.

本発明の実施形態の多結晶シリコン塊表面の金属不純物分析方法は、図1に示すように多結晶シリコン塊の質量(W)を測定する工程1と、多結晶シリコン塊を上部が開口した容器に収納する工程2と、硝酸とフッ化水素酸と過酸化水素水との混合溶液を所定のV/Wの割合で多結晶シリコン塊に滴下する工程3と、滴下した液を多結晶シリコン塊の表面に行き渡らせる工程4と、多結晶シリコン塊の表面から流下した液を採取する工程5と、採取した液に含まれる金属のICP-MS法による定量分析工程6とを含む。以下、工程順に詳述する。 The method for analyzing metal impurities on the surface of a polycrystalline silicon chunk according to an embodiment of the present invention includes, as shown in FIG. 1, a step 1 of measuring the mass (W) of the polycrystalline silicon chunk, and a step 2 of storing a mixed solution of nitric acid, hydrofluoric acid and hydrogen peroxide in a polycrystalline silicon lump at a predetermined V/W ratio; step 4 of spreading over the surface of the polycrystalline silicon mass, step 5 of sampling the liquid that has flowed down from the surface of the polycrystalline silicon lump, and step 6 of quantitatively analyzing the metal contained in the sampled liquid by the ICP-MS method. Hereinafter, it will be described in detail in the order of steps.

〔多結晶シリコン塊の質量(W)測定〕
本実施形態の多結晶シリコン塊は、シーメンス法で製造された棒状の多結晶シリコンをタングステン製のハンマー等で粉砕した後、フッ化水素酸と硝酸の混酸でエッチング処理して、粉砕時に付着した金属不純物を低減した多結晶シリコン塊であることが好ましい。こうした多結晶シリコン塊を、次に述べる混合溶液の量を減らして、分析用サンプルを作製するためのコストを低減するために、好ましくは40g~80g、更に好ましくは50g~70gサンプルとして1個又は複数個採取して、その質量(W)を測定する。多結晶シリコン塊は、次に述べる容器の大きさに依存し、この容器に収納することが可能な大きさであり、塊の長手方向の大きさが好ましくは10mm~50mm、更に好ましくは20mm~40mmである。
[Mass (W) measurement of polycrystalline silicon mass]
The polycrystalline silicon mass of the present embodiment is obtained by pulverizing rod-shaped polycrystalline silicon produced by the Siemens method with a tungsten hammer or the like, followed by etching treatment with a mixed acid of hydrofluoric acid and nitric acid, and adhering during pulverization. It is preferably a polycrystalline silicon mass with reduced metal impurities. In order to reduce the amount of the mixed solution described below and reduce the cost for producing a sample for analysis, such a polycrystalline silicon lump is preferably 40 g to 80 g, more preferably 50 g to 70 g. A plurality of samples are collected and their mass (W) is measured. The polycrystalline silicon mass depends on the size of the container described below, and has a size that can be accommodated in this container. 40 mm.

〔多結晶シリコン塊の容器への収納〕
本実施形態の多結晶シリコン塊を収納する容器は、上部が開口した容器であって、耐薬品性のあるフッ素樹脂製であることが好ましい。フッ素樹脂としては、ポリテトラフルオロエチレン(PTFE)、ポリフッ化ビニリデン、テトラフルオロエチレン-ヘキサフルオロプロピレンコポリマー、テトラフルオロエチレン-パーフルオロアルコキシエチレンコポリマー(PFA)等が例示される。この容器の開口広さ及び容積は、上記多結晶シリコン塊を収納し得る開口広さ及び容積であればよい。容器の底部広さは、次に述べる容器底部に溜まった液をマイクロピペットで採取し得る広さであることが好ましい。また容器の深さは、次に述べる混合溶液を滴下するときに滴下した混合溶液がサンプルに当たって容器外に飛散しない程度の深さを有することが好ましい。
[Containment of polycrystalline silicon mass in container]
The container for storing the polycrystalline silicon mass of the present embodiment is preferably a container with an open top and made of chemical-resistant fluororesin. Examples of the fluororesin include polytetrafluoroethylene (PTFE), polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA), and the like. The opening width and volume of this container may be any opening width and volume that can accommodate the polycrystalline silicon mass. The width of the bottom portion of the container is preferably such that the liquid accumulated at the bottom portion of the container, which will be described below, can be sampled with a micropipette. Further, the depth of the container is preferably such that when the mixed solution described below is dropped, the dropped mixed solution does not hit the sample and scatter out of the container.

〔混合溶液(V)の所定の割合(V/W)での多結晶シリコン塊への滴下〕
本実施形態の混合溶液は、硝酸とフッ化水素酸と過酸化水素水との混合溶液である。好ましくは、濃度1質量%~5質量%の硝酸と、濃度1質量%~5質量%のフッ化水素酸と、濃度1質量%~3質量%の過酸化水素水との混合溶液である。混合溶液中のフッ化水素酸は、多結晶シリコン塊の表面に存在する二酸化シリコンを分解するために使用される。混合溶液中の過酸化水素水は、塊表面上への金属堆積(plating)からCuのようなある種の金属をより容易に回収するために使用される。混合溶液中の硝酸は、過酸化水素水の酸化力を高め、塊表面における金属微粒子の溶解を助けるために使用される。上記の濃度範囲の硝酸、フッ化水素酸及び過酸化水素の溶液を用いることにより、この混合溶液をICP-MS装置に直接導入したときに、ICP-MS装置の機器の損傷が抑制される。
[Dropping of Mixed Solution (V) at Predetermined Ratio (V/W) onto Polycrystalline Silicon Block]
The mixed solution of this embodiment is a mixed solution of nitric acid, hydrofluoric acid and hydrogen peroxide solution. Preferred is a mixed solution of nitric acid with a concentration of 1% to 5% by mass, hydrofluoric acid with a concentration of 1% by mass to 5% by mass, and hydrogen peroxide solution with a concentration of 1% by mass to 3% by mass. Hydrofluoric acid in the mixed solution is used to decompose silicon dioxide present on the surface of the polycrystalline silicon mass. Aqueous hydrogen peroxide in the mixed solution is used to more easily recover certain metals such as Cu from metal plating on the bulk surface. Nitric acid in the mixed solution is used to increase the oxidizing power of the hydrogen peroxide solution and help dissolve the fine metal particles on the surface of the mass. By using the solutions of nitric acid, hydrofluoric acid and hydrogen peroxide within the above concentration range, damage to the equipment of the ICP-MS apparatus is suppressed when this mixed solution is directly introduced into the ICP-MS apparatus.

上記混合溶液中の硝酸とフッ化水素酸と過酸化水素水の配合割合は、質量%の比率で硝酸:フッ化水素酸:過酸化水素水=1.4:2:2であることが好ましい。少量の硝酸とフッ化水素酸と過酸化水素水を上記濃度と質量比で含む混合溶液を用いることにより、多結晶シリコン塊の表面から金属不純物を効率よく回収することができる。またフッ化水素酸の量を調整することにより、溶解するシリコンマトリックスの量を調整することができる。 The mixing ratio of nitric acid, hydrofluoric acid and hydrogen peroxide solution in the mixed solution is preferably nitric acid:hydrofluoric acid:hydrogen peroxide solution=1.4:2:2 in mass %. . By using a mixed solution containing a small amount of nitric acid, hydrofluoric acid, and hydrogen peroxide solution at the above concentration and mass ratio, metal impurities can be efficiently recovered from the surface of the polycrystalline silicon lump. Also, by adjusting the amount of hydrofluoric acid, the amount of dissolved silicon matrix can be adjusted.

上記混合溶液の多結晶シリコン塊への滴下量は、多結晶シリコン塊の質量(W)に対する混合溶液の容量(V)が10%~20%、好ましくは10%の割合(V/W)になるように、決められる。V/Wが10%未満では、塊表面に滴下した液が塊表面全体を均一に行き渡らない上、完全に流下せず、結果として高精度に金属不純物を定量分析できない。また20%を超えると、分析する元素の液中濃度のレベルが低くなり、ICP-MS装置のカウントが低くなって、高感度で正確な分析をすることができない。混合溶液の滴下は、容器内の多結晶シリコン塊表面全体に混合溶液を行き渡らせるように行われる。こうした滴下により、多結晶シリコン塊表面の金属不純物を的確に分析することができる。この滴下器具としては、マイクロピペットが好ましい。上述した多結晶シリコン塊の質量が40g~80gの場合には、滴下量は4ml~8mlであることが好ましい。 The volume (V) of the mixed solution to the mass (W) of the polycrystalline silicon lump is 10% to 20%, preferably 10% (V/W). It is decided so that it becomes. If the V/W is less than 10%, the liquid dropped onto the surface of the lump cannot spread evenly over the entire surface of the lump and does not flow down completely. On the other hand, if it exceeds 20%, the concentration level of the element to be analyzed in the liquid becomes low, the count of the ICP-MS apparatus becomes low, and highly sensitive and accurate analysis cannot be performed. Dropping of the mixed solution is performed so as to spread the mixed solution over the entire surface of the polycrystalline silicon mass in the container. Such dropping allows accurate analysis of metal impurities on the surface of the polycrystalline silicon chunk. A micropipette is preferable as the dropping device. When the mass of the polycrystalline silicon mass described above is 40 g to 80 g, the dropping amount is preferably 4 ml to 8 ml.

〔滴下液の多結晶シリコン塊表面への行き渡らせ〕
上部が開口した容器の上方から容器内に収納された多結晶シリコン塊表面全体に上記混合溶液をマイクロピペットにより滴下すると、滴下して混合溶液は塊表面全体に行き渡る。そしてポリシリコン塊の表面に存在するシリコン酸化膜と混合溶液中に存在するフッ化水素酸との反応によりシリコン表面は疎水性になるので、滴下した混合溶液は多結晶シリコン塊の表面を自重で流れ落ちて容器の底部に溜まる。本実施形態の方法では、特許文献1に示すようなローラーシェイカーを必要としない。なお、容器の底部に溜まった混合溶液を短時間、例えば1~2分間程度容器とともに揺り動かして、容器内の多結晶シリコン塊表面に混合溶液を再度行き渡らせてもよい。
[Spreading the dripping liquid over the surface of the polycrystalline silicon mass]
When the above mixed solution is dropped from above the container with an open top onto the entire surface of the polycrystalline silicon block housed in the container using a micropipette, the dropped mixed solution spreads over the entire surface of the block. The silicon surface becomes hydrophobic due to the reaction between the silicon oxide film present on the surface of the polysilicon lump and the hydrofluoric acid present in the mixed solution. It runs down and collects at the bottom of the container. The method of this embodiment does not require a roller shaker as shown in Patent Document 1. The mixed solution collected at the bottom of the container may be shaken together with the container for a short period of time, for example, for about 1 to 2 minutes, so that the mixed solution spreads again over the surface of the polycrystalline silicon mass in the container.

〔多結晶シリコン塊表面から流下した液の採取〕
多結晶シリコン塊表面から流下して容器底部に溜まった液は、容器上方から容器底部に挿入したマイクロピペットのような器具により採取される。特許文献1に示すように密閉した容器を開けて回収液を採取する必要はない。
[Sampling of liquid flowing down from the surface of polycrystalline silicon mass]
The liquid that has flowed down from the surface of the polycrystalline silicon mass and accumulated at the bottom of the container is collected by an instrument such as a micropipette inserted into the bottom of the container from above. It is not necessary to open a sealed container to collect the recovered liquid as shown in Patent Document 1.

〔採取した液のICP-MS法による定量分析〕
採取した液は分析用サンプルとして、直接ICP-MS装置に導入され、そこで液に含まれる金属不純物の定量分析が行われる。従来の採取した液の濃縮、乾固は不要であり、また長い時間をかけて分析用サンプルからシリコンマトリックスを揮散分離させる作業も行う必要はない。
[Quantitative analysis of collected liquid by ICP-MS method]
The collected liquid is introduced directly into an ICP-MS apparatus as an analysis sample, where quantitative analysis of metal impurities contained in the liquid is performed. The conventional concentration and drying of the sampled liquid is not required, nor is it necessary to take a long time to volatilize and separate the silicon matrix from the sample for analysis.

以上述べたように、本実施形態の方法では、定量分析用の混合溶液の量が少量で済むため、混合溶液に含まれる酸からの分析用サンプルへの汚染を低減することができる。またシリコンマトリックスの溶解量が少ないため、分析用サンプルをシリコンマトリックスを揮散分離させる必要がない。更に混合溶液の多結晶シリコン塊への滴下から流下までの時間は約1分以内であり、分析用サンプルの採取まで極めて短時間で行うことができる。 As described above, in the method of the present embodiment, the amount of the mixed solution for quantitative analysis is small, so contamination of the sample for analysis by the acid contained in the mixed solution can be reduced. In addition, since the amount of dissolution of the silicon matrix is small, it is not necessary to volatilize and separate the silicon matrix from the sample for analysis. Furthermore, the time from dropping the mixed solution onto the polycrystalline silicon mass until it flows down is about 1 minute or less, and the sample for analysis can be collected in an extremely short time.

次に本発明の実施例を比較例とともに詳しく説明する。 Next, examples of the present invention will be described in detail together with comparative examples.

<実施例1>
多結晶シリコン塊を約50g秤量し、これをポリテトラフルオロエチレン(テフロン(登録商標))製の上部が開口した容積が100mlの清浄なビーカー(容器)に収納した。濃度1.4質量%の硝酸と、濃度2質量%のフッ化水素酸と、濃度2質量%の過酸化水素水を混合した混合溶液を用意した。この混合溶液は、濃度70質量%の硝酸2mlと、濃度38質量%のフッ化水素酸6mlと、濃度35質量%の過酸化水素水6.5mlとを純水86.1mlで希釈することにより、液量が100mlになるように調製した。精密マイクロピペットで採取した混合溶液5mlを容器内に収納した多結晶シリコン塊(質量約50g)表面全体に滴下した。滴下液を多結晶シリコン塊表面全体に行き渡らせ、流下させた後、容器底部に溜まった液2mlを精密マイクロピペットで採取した。これをICP-MS装置(アジレント社製、品番7700X)に直接導入して、採取した液中の金属不純物の定量分析を行った。
<Example 1>
About 50 g of a polycrystalline silicon mass was weighed and placed in a clean beaker (container) made of polytetrafluoroethylene (Teflon (registered trademark)) having an open top and a capacity of 100 ml. A mixed solution was prepared by mixing nitric acid with a concentration of 1.4% by mass, hydrofluoric acid with a concentration of 2% by mass, and aqueous hydrogen peroxide with a concentration of 2% by mass. This mixed solution is obtained by diluting 2 ml of nitric acid with a concentration of 70% by mass, 6 ml of hydrofluoric acid with a concentration of 38% by mass, and 6.5 ml of hydrogen peroxide with a concentration of 35% by mass with 86.1 ml of pure water. , was prepared so that the liquid volume was 100 ml. 5 ml of the mixed solution collected with a precision micropipette was dropped onto the entire surface of a polycrystalline silicon mass (about 50 g in mass) housed in a container. After the dripping liquid was distributed over the entire surface of the polycrystalline silicon block and allowed to flow down, 2 ml of the liquid collected at the bottom of the container was collected with a precision micropipette. This was directly introduced into an ICP-MS apparatus (manufactured by Agilent, product number 7700X) to perform quantitative analysis of metal impurities in the sampled liquid.

<実施例2>
実施例1と同じ多結晶シリコン塊を約50g秤量した。混合溶液のマイクロピペットによる採取と滴下の量を10mlに変えた以外、実施例1と同様にして、容器底部に溜まった液を精密マイクロピペットで採取し、これを実施例1で用いたICP-MS装置に直接導入して、採取した液中の金属不純物の定量分析を行った。
<Example 2>
About 50 g of the same polycrystalline silicon mass as in Example 1 was weighed. In the same manner as in Example 1, except that the mixed solution was collected with a micropipette and the amount of dropping was changed to 10 ml, the liquid accumulated at the bottom of the container was collected with a precision micropipette, and the ICP- used in Example 1 was collected. Quantitative analysis of metal impurities in the sampled liquid was performed by directly introducing it into the MS apparatus.

<比較例1>
多結晶シリコン塊のサンプルとこのサンプルが十分浸漬するだけの硝酸とフッ化水素酸の混酸による従来法により、サンプルに含まれる金属不純物の定量分析を行った。即ち、実施例1と同じ多結晶シリコン塊を約50g秤量し、実施例1と同じビーカーに収納した。濃度70質量%の硝酸40mlと、濃度38質量%のフッ化水素酸10mlとを混合した液量が50mlの混合溶液を用意し、ビーカーに注入し、多結晶シリコン塊を混合溶液に埋没させた。多結晶シリコン塊の質量(W)に対する混合溶液の容量(V)の割合(V/W)は約100%であった。この状態で多結晶シリコン塊を混合溶液に6分間浸漬させた。その後、ビーカー内の混合溶液25mlを精密マイクロピペットで採取し、テフロン(登録商標)製の清浄な100mlのビーカー内に滴下し、この滴下液の入ったビーカーを230℃に維持されたホットプレート上に置き、滴下液を蒸発させた。蒸発により濃縮乾固した残渣に濃度1.4質量%の硝酸5ml加えて分析用サンプルを作製した。この分析用サンプルを精密マイクロピペットで採取して、実施例1と同じICP-MS装置に直接導入して、採取した液中の金属不純物の定量分析を行った。
<Comparative Example 1>
Quantitative analysis of metal impurities contained in a sample was performed by a conventional method using a sample of polycrystalline silicon mass and a mixed acid of nitric acid and hydrofluoric acid sufficient to immerse the sample. That is, about 50 g of the same polycrystalline silicon mass as in Example 1 was weighed and placed in the same beaker as in Example 1. A mixed solution with a liquid volume of 50 ml was prepared by mixing 40 ml of nitric acid with a concentration of 70% by mass and 10 ml of hydrofluoric acid with a concentration of 38% by mass, and poured into a beaker to bury the polycrystalline silicon mass in the mixed solution. . The ratio (V/W) of the volume (V) of the mixed solution to the mass (W) of the polycrystalline silicon mass was about 100%. In this state, the polycrystalline silicon mass was immersed in the mixed solution for 6 minutes. After that, 25 ml of the mixed solution in the beaker was collected with a precision micropipette, dropped into a clean 100 ml beaker made of Teflon (registered trademark), and the beaker containing the dropped liquid was placed on a hot plate maintained at 230 ° C. and allowed to evaporate. A sample for analysis was prepared by adding 5 ml of nitric acid having a concentration of 1.4% by mass to the residue concentrated to dryness by evaporation. This sample for analysis was collected with a precision micropipette and directly introduced into the same ICP-MS apparatus as in Example 1 to perform quantitative analysis of metal impurities in the sampled liquid.

実施例1、2及び比較例1の各分析用サンプルの定量分析結果を次の表1に示す。表1には、多結晶シリコン塊の質量(W)に対する混合溶液の容量(V)の割合(V/W)が10%と20%のときの本発明の分析法の機器の検出限界も元素別に示す。また従来の分析法の機器の検出限界も元素別に示す。 The results of quantitative analysis of each analysis sample of Examples 1 and 2 and Comparative Example 1 are shown in Table 1 below. Table 1 also shows the detection limit of the instrument for the analysis method of the present invention when the ratio (V/W) of the volume (V) of the mixed solution to the mass (W) of the polycrystalline silicon lump is 10% and 20%. shown separately. In addition, the detection limit of conventional analytical instruments is also shown for each element.

Figure 0007303662000001
Figure 0007303662000001

表1から明らかなように、本発明の分析法に基づいた実施例1(V/W10%)の分析結果は、V/Wが10%の機器の検出限界より約10倍優れていた。また同じく本発明の分析法に基づいた実施例2(V/W20%)の分析結果は、V/Wが20%の機器の検出限界より約5倍優れていた。これらの機器の検出限界は、比較のために示した従来の分析法の機器の検出限界より遙かに優れていた。
従来の分析法の機器の検出限界が高い原因は、ホットプレート等に起因したクリーンルーム環境からの汚染やオペレーターがサンプルに接触したときの汚染や加熱したビーカーや高濃度の酸からの汚染等であったと考えられる。
As can be seen from Table 1, the analytical results of Example 1 (10% V/W) based on the analytical method of the present invention were about 10 times better than the detection limit of the 10% V/W instrument. The analytical results of Example 2 (20% V/W), also based on the analytical method of the present invention, were about 5 times better than the detection limit of the 20% V/W instrument. The detection limits of these instruments were far superior to those of the conventional analytical methods shown for comparison.
The high detection limits of instruments for conventional analytical methods are due to contamination from the clean room environment caused by hot plates, contamination when the operator comes into contact with the sample, contamination from heated beakers and high concentrations of acid. It is thought that

また、混合溶液のマイクロピペットによる採取と滴下の量を5mlと10mlとした実施例1と実施例2の各分析結果はほぼ同じであった。ただし、採取と滴下の量を5mlにした方が、採取と滴下の量を10mlにするよりも、より正確な分析結果が得られることが分かった。これはサンプルを作製するときに使用される10mlの液の希釈係数が5mlの液の希釈係数よりも大きいためと考えられる。従来の分析法の機器の検出限界は、実際のサンプルの濃度に非常に近いため、ICP-MS装置では、高精度の分析は困難である。これに対して実施例1及び2の分析法で定量分析した値は、本発明の分析法の機器の検出限界よりも高いため、高精度の分析が可能であることが分かった。 Further, the analysis results of Examples 1 and 2, in which the mixed solution was sampled with a micropipette and dropped in amounts of 5 ml and 10 ml, were almost the same. However, it was found that the collection and dropping amount of 5 ml yielded more accurate analysis results than the collection and dropping amount of 10 ml. It is considered that this is because the dilution factor of 10 ml of liquid used for sample preparation is greater than that of 5 ml of liquid. Since the detection limit of instruments for conventional analytical methods is very close to the concentration of the actual sample, it is difficult for ICP-MS instruments to perform high-precision analysis. On the other hand, the values obtained by quantitative analysis by the analytical methods of Examples 1 and 2 are higher than the detection limit of the instrument for the analytical method of the present invention, so it was found that highly accurate analysis is possible.

<実施例3~5>
異なる多結晶シリコンメーカーにおいて、シーメンス法によりそれぞれ製造された棒状の多結晶シリコンを粉砕した後、フッ化水素酸と硝酸の混酸でエッチング処理した多結晶シリコン塊A(実施例3)、多結晶シリコン塊B(実施例4)、多結晶シリコン塊C(実施例5)を用意した。これらの多結晶シリコン塊A、B、Cの各表面の金属不純物から得られた3種の分析用サンプルを実施例1で用いたICP-MS装置により定量分析した。3種の分析用サンプルは実施例1と同様にして作製した。それらの結果を次の表2に示す。表2は、それぞれの多結晶シリコンメーカーのサンプルによって、汚染のレベルが異なることを示している。表2の結果から明らかなように、本発明の分析法では、酸の量や環境の汚染のレベルをコントロールし、サンプル回収液の高い濃縮率によって、各多結晶シリコンメーカーの微量な汚染レベルを識別し、低レベルでの分析を高精度で行うことが可能であることが分かった。
<Examples 3 to 5>
Polycrystalline silicon mass A (Example 3) obtained by pulverizing rod-shaped polycrystalline silicon manufactured by the Siemens method at different polycrystalline silicon manufacturers and then etching with a mixed acid of hydrofluoric acid and nitric acid (Example 3), polycrystalline silicon A mass B (Example 4) and a polycrystalline silicon mass C (Example 5) were prepared. Three types of analysis samples obtained from metal impurities on the surfaces of these polycrystalline silicon chunks A, B, and C were quantitatively analyzed by the ICP-MS apparatus used in Example 1. Three samples for analysis were prepared in the same manner as in Example 1. The results are shown in Table 2 below. Table 2 shows that the samples from each polysilicon manufacturer have different levels of contamination. As is clear from the results in Table 2, in the analysis method of the present invention, the amount of acid and the level of environmental contamination are controlled, and the high concentration rate of the sample recovery solution enables the trace contamination level of each polycrystalline silicon manufacturer to be detected. It turns out that it is possible to discriminate and perform low-level analysis with high accuracy.

Figure 0007303662000002
Figure 0007303662000002

<比較例2>
多結晶シリコン塊のサンプルとこのサンプルが十分浸漬するだけの硝酸とフッ化水素酸の混酸による従来法により、サンプルに含まれる金属不純物の定量分析を行った。即ち、実施例3と同じ多結晶シリコン塊を約50g秤量し、実施例1と同じビーカーに収納した。濃度70質量%の硝酸40mlと、濃度38質量%のフッ化水素酸10mlとを混合した液量が50mlの混合溶液を用意し、ビーカーに注入し、多結晶シリコン塊を混合溶液に埋没させた。多結晶シリコン塊の質量(W)に対する混合溶液の容量(V)の割合(V/W)は約100%であった。この状態で多結晶シリコン塊を混合溶液に6分間浸漬させた。その後、ビーカー内の混合溶液25mlを精密マイクロピペットで採取し、テフロン(登録商標)製の清浄な100mlのビーカー内に滴下し、この滴下液の入ったビーカーを230℃に維持されたホットプレート上に置き、滴下液を蒸発させた。蒸発により濃縮乾固した残渣に濃度1.4質量%の硝酸5ml加えて分析用サンプルを作製した。この分析用サンプルを精密マイクロピペットで採取して、実施例1と同じICP-MS装置に直接導入して、採取した液中の金属不純物の定量分析を行った。実施例3の分析用サンプルによる定量分析とこの比較例2の分析用サンプルによる定量分析の結果を次の表3に示す。比較例2の分析用サンプルの作製時間は120分であって長時間であったのに対して、実施例3の分析用サンプルの作製時間は1~2分であり、極めて短時間であった。
<Comparative Example 2>
Quantitative analysis of metal impurities contained in a sample was performed by a conventional method using a sample of polycrystalline silicon mass and a mixed acid of nitric acid and hydrofluoric acid sufficient to immerse the sample. That is, about 50 g of the same polycrystalline silicon mass as in Example 3 was weighed and placed in the same beaker as in Example 1. A mixed solution with a liquid volume of 50 ml was prepared by mixing 40 ml of nitric acid with a concentration of 70% by mass and 10 ml of hydrofluoric acid with a concentration of 38% by mass, and poured into a beaker to bury the polycrystalline silicon mass in the mixed solution. . The ratio (V/W) of the volume (V) of the mixed solution to the mass (W) of the polycrystalline silicon mass was about 100%. In this state, the polycrystalline silicon mass was immersed in the mixed solution for 6 minutes. After that, 25 ml of the mixed solution in the beaker was collected with a precision micropipette, dropped into a clean 100 ml beaker made of Teflon (registered trademark), and the beaker containing the dropped liquid was placed on a hot plate maintained at 230 ° C. and allowed to evaporate. A sample for analysis was prepared by adding 5 ml of nitric acid having a concentration of 1.4% by mass to the residue concentrated to dryness by evaporation. This sample for analysis was collected with a precision micropipette and directly introduced into the same ICP-MS apparatus as in Example 1 to perform quantitative analysis of metal impurities in the sampled liquid. The quantitative analysis results of the analysis sample of Example 3 and the analysis sample of Comparative Example 2 are shown in Table 3 below. The preparation time for the sample for analysis in Comparative Example 2 was 120 minutes, which was a long time, whereas the preparation time for the sample for analysis in Example 3 was 1 to 2 minutes, which was extremely short. .

Figure 0007303662000003
Figure 0007303662000003

表3から明らかなように、比較例2のICP-MS法による定量分析結果では、ほとんどの元素は分析が可能であったが、BとPの元素の分析値は、大きな差が見られた。この理由は比較例2のサンプルの処理時間が長いため、環境の汚染の影響でコンタミネーション(汚染物)がかなり高いレベルで検出されたことによると考えられる。実施例3のICP-MS法による定量分析結果では、分析カウントが高く、環境や酸等の影響がほとんどないため、高精度で分析することが可能であることが分かった。 As is clear from Table 3, in the quantitative analysis results by the ICP-MS method of Comparative Example 2, most of the elements could be analyzed, but there was a large difference in the analysis values of the elements B and P. . The reason for this is considered to be that the sample of Comparative Example 2 was treated for a long time, so that a considerably high level of contamination was detected due to the influence of environmental contamination. The results of the quantitative analysis by the ICP-MS method in Example 3 showed that the analysis count was high and that the influence of the environment, acid, etc. was negligible, so that the analysis could be performed with high precision.

本発明の多結晶シリコン塊表面の金属不純物分析方法は、高性能のシリコン系半導体デバイスに用いられるシリコンチップ素子を製造する材料である多結晶シリコン塊を評価するための金属不純物の汚染レベルを正確にかつ高精度に分析することができる。 The method for analyzing metal impurities on the surface of polycrystalline silicon masses according to the present invention accurately determines the contamination level of metal impurities for evaluating polycrystalline silicon masses, which are materials for manufacturing silicon chip elements used in high-performance silicon-based semiconductor devices. It is possible to analyze with high precision.

Claims (4)

多結晶シリコン塊の質量(W)(単位:g)を測定し、前記多結晶シリコン塊を上部が開口した容器に収納し、硝酸とフッ化水素酸と過酸化水素水との混合溶液を、前記多結晶シリコン塊の質量(W)に対する前記混合溶液の容量(V)(単位:ml)の割合(V/W)(単位:g/ml)が10%~20%になるように、前記容器内の多結晶シリコン塊の上からマイクロピペットにより滴下して前記多結晶シリコン塊の表面に前記混合溶液の自重で前記混合溶液を行き渡らせた後、前記多結晶シリコン塊の表面から前記混合溶液の自重で流下して前記容器底部に溜まった液を前記容器の上方から前記容器底部に挿入したマイクロピペットにより採取して、採取した液を分析用サンプルとして、誘導結合プラズマ質量分析装置に直接導入することにより、前記採取液に含まれるP、B、As及びP、B、As以外の金属からなる群より選ばれた1種又は2種以上の金属不純物を誘導結合プラズマ質量分析法により定量分析することを特徴とする多結晶シリコン塊表面の金属不純物分析方法。 The mass (W) (unit: g) of the polycrystalline silicon mass was measured, and the polycrystalline silicon mass was placed in a container with an open top. The above- described After the mixed solution is spread over the surface of the polycrystalline silicon lump by its own weight , the mixed solution is dropped from above the polycrystalline silicon lump in the container from the surface of the polycrystalline silicon lump. The liquid accumulated at the bottom of the container by its own weight is collected by a micropipette inserted from above the container into the bottom of the container , and the collected liquid is used as an analysis sample and introduced directly into the inductively coupled plasma mass spectrometer. By doing so, one or more metal impurities selected from the group consisting of P, B, As and metals other than P, B, As contained in the sampled liquid are quantitatively analyzed by inductively coupled plasma mass spectrometry. A method for analyzing metal impurities on the surface of a polycrystalline silicon lump, characterized by: 前記混合溶液は、濃度1質量%~5質量%の硝酸と、濃度1質量%~5質量%のフッ化水素酸と、濃度1質量%~3質量%の過酸化水素水との混合溶液である請求項1記載の多結晶シリコン塊表面の金属不純物分析方法。 The mixed solution is a mixed solution of nitric acid with a concentration of 1% by mass to 5% by mass, hydrofluoric acid with a concentration of 1% by mass to 5% by mass, and hydrogen peroxide solution with a concentration of 1% by mass to 3% by mass. A method for analyzing metal impurities on the surface of a polycrystalline silicon lump according to claim 1. 前記容器に収納する多結晶シリコン塊の質量(W)が40g~80gである請求項1又は2記載の多結晶シリコン塊表面の金属不純物分析方法。 3. The method for analyzing metal impurities on the surface of a polycrystalline silicon lump according to claim 1, wherein the mass (W) of the polycrystalline silicon lump contained in the container is 40 g to 80 g. 前記P、B、As以外の金属が、Li、Na、Mg、Al、K、Ca、Cr、Mn、Fe、Ni、Co、Cu、Zn、Sr、Mo、Cd、Ba及びPbからなる群より選ばれた1種又は2種以上の金属である請求項1ないし3いずれか1項に記載の多結晶シリコン塊表面の金属不純物分析方法。

The metal other than P, B and As is from the group consisting of Li, Na, Mg, Al, K, Ca, Cr, Mn, Fe, Ni, Co, Cu, Zn, Sr, Mo, Cd, Ba and Pb 4. The method for analyzing metal impurities on the surface of a polycrystalline silicon lump according to any one of claims 1 to 3, wherein the selected metal is one or more metals.

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