JP6732595B2 - Method for measuring metal impurity concentration in polycrystalline silicon - Google Patents

Method for measuring metal impurity concentration in polycrystalline silicon Download PDF

Info

Publication number
JP6732595B2
JP6732595B2 JP2016154011A JP2016154011A JP6732595B2 JP 6732595 B2 JP6732595 B2 JP 6732595B2 JP 2016154011 A JP2016154011 A JP 2016154011A JP 2016154011 A JP2016154011 A JP 2016154011A JP 6732595 B2 JP6732595 B2 JP 6732595B2
Authority
JP
Japan
Prior art keywords
polycrystalline silicon
concentration
single crystal
metal
measuring
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
JP2016154011A
Other languages
Japanese (ja)
Other versions
JP2018021852A (en
Inventor
明 卯野
明 卯野
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tokuyama Corp
Original Assignee
Tokuyama Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tokuyama Corp filed Critical Tokuyama Corp
Priority to JP2016154011A priority Critical patent/JP6732595B2/en
Publication of JP2018021852A publication Critical patent/JP2018021852A/en
Application granted granted Critical
Publication of JP6732595B2 publication Critical patent/JP6732595B2/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Landscapes

  • Sampling And Sample Adjustment (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Description

本発明は、多結晶シリコン中に含まれる金属不純物濃度の測定方法、詳しくは、測定対象の多結晶シリコンを用いてFZ法により成長させたシリコン単結晶を分析し、該多結晶シリコンに含まれる金属不純物濃度を高感度に測定する方法に関する。 The present invention relates to a method for measuring the concentration of metal impurities contained in polycrystalline silicon, specifically, to analyze a silicon single crystal grown by the FZ method using polycrystalline silicon to be measured, and to analyze the content of the polycrystalline silicon contained in the polycrystalline silicon. The present invention relates to a method for measuring a metal impurity concentration with high sensitivity.

シリコンウェーハの大口径化、デバイスの高集積化に伴い、シリコンウェーハ中の金属不純物の低減化が求められている。このため、シリコンウェーハの原料である多結晶シリコンについても同様に金属不純物を低減化することが必要であり、それに伴って、多結晶シリコンの金属不純物濃度を評価するための分析技術を確立することが望まれている。 With the increase in diameter of silicon wafers and the higher integration of devices, it is required to reduce metal impurities in silicon wafers. Therefore, it is necessary to reduce the metal impurities also in the polycrystalline silicon that is the raw material of the silicon wafer, and along with that, establish an analytical technique for evaluating the metal impurity concentration of the polycrystalline silicon. Is desired.

従来、多結晶シリコンの不純物濃度を定量する方法として、化学分析及び放射化分析等が知られている。しかし、感度が低く、さらに外部汚染の影響も受けやすいため、不純物含有量が極端に少ない多結晶シリコンに対しては、これを十分に定量することが困難であった。 Conventionally, chemical analysis and activation analysis are known as methods for quantifying the impurity concentration of polycrystalline silicon. However, since it has low sensitivity and is easily affected by external contamination, it has been difficult to sufficiently quantify polycrystalline silicon having an extremely low impurity content.

このため、多結晶シリコンに含まれるカーボンおよびド―パント不純物濃度を高感度に分析する方法として、例えば、「高純度多結晶シリコン標準品規格」では、次のような方法が示されている。即ち、まず、多結晶シリコンロッドの直胴部から直径方向に丸棒を切り出した後、この多結晶シリコン棒をFZ(Float-Zone)法により単結晶化し、次いで、この単結晶棒の任意の直胴部から試料を切り出し、フォトルミネッセンス法により各種不純物の測定を行う。そして、得られた測定値を基に理論計算して、元の多結晶シリコンロッドに含まれる不純物量に換算する方法である。(非特許文献1参照)。一方、金属不純物の分析については、金属は偏析係数が小さいため、上記方法では、シリコン単結晶棒胴部から切り出した試料に含まれる量が微少になり、高感度の要求に対して十分に満足のいく結果は得にくい。従って、多結晶シリコンの表面部を対象として、フッ硝酸水溶液に浸漬して分析するのが常法であった。 For this reason, as a method for highly sensitively analyzing the concentration of carbon and dopant impurities contained in polycrystalline silicon, for example, the “high-purity polycrystalline silicon standard product standard” shows the following method. That is, first, a round bar is cut out in the diameter direction from the straight body part of the polycrystalline silicon rod, the polycrystalline silicon rod is made into a single crystal by the FZ (Float-Zone) method, and then any of the single crystal rods is cut. A sample is cut out from the straight body, and various impurities are measured by the photoluminescence method. Then, it is a method of theoretically calculating based on the obtained measured value and converting into the amount of impurities contained in the original polycrystalline silicon rod. (See Non-Patent Document 1). On the other hand, regarding the analysis of metal impurities, since the metal has a small segregation coefficient, the above method results in a very small amount contained in the sample cut out from the body of the silicon single crystal ingot, which is sufficiently satisfactory for high sensitivity. Reliable results are hard to obtain. Therefore, it has been the usual method to analyze the surface portion of polycrystalline silicon by immersing it in an aqueous solution of hydrofluoric nitric acid.

こうした中、測定試料として、前記FZ法により製造するシリコン単結晶棒における最終固化部(尾部)を用いることが提案されている(特許文献1及び2参照)。即ち、係る最終固化部には、測定試料に含有されていた金属不純物が高濃度に濃縮されるため、ここを採取して分析すれば、前記金属不純物の分析感度を高めることが可能というものである。この方法において、最終固化部における金属不純物濃度の分析は、これをフッ硝酸水溶液に浸漬して最終固化部を分解して金属を抽出し、この回収液を一旦蒸発乾固させた後、残滓を酸溶液に再溶解させて、誘導結合プラズマ質量分析法等により化学分析することで行われている。 Under these circumstances, it has been proposed to use a final solidified portion (tail portion) of a silicon single crystal ingot manufactured by the FZ method as a measurement sample (see Patent Documents 1 and 2). That is, since the metal impurities contained in the measurement sample are concentrated to a high concentration in the final solidification part, it is possible to enhance the analysis sensitivity of the metal impurities by collecting and analyzing the metal impurities. is there. In this method, the metal impurity concentration in the final solidification part is analyzed by immersing it in an aqueous solution of hydrofluoric nitric acid to decompose the final solidification part to extract metal, and once the recovered liquid is evaporated to dryness, the residue is removed. It is performed by redissolving it in an acid solution and performing chemical analysis by inductively coupled plasma mass spectrometry or the like.

「電子情報技術産業情報規格JEITA EM-3601A 高純度多結晶シリコン標準品規格」、社団法人電子情報技術産業協会、2004年9月"Electronic Information Technology Industrial Information Standard JEITA EM-3601A High Purity Polycrystalline Silicon Standard Product Standard", Japan Electronics and Information Technology Industries Association, September 2004

特開平5−26803号公報JP-A-5-26803 特開平11−304791号公報JP, 11-304791, A

しかしながら、上記FZ法により得たシリコン単結晶棒の最終固化部を分析対象としても、従来提案の手法では、その分析感度は今一歩十分ではなく、さらに高感度なものに改良することが求められていた。 However, even when the final solidified portion of the silicon single crystal ingot obtained by the FZ method is used as an analysis target, the analysis sensitivity of the conventional proposal is not yet sufficient, and it is required to improve the analysis sensitivity to a higher sensitivity. Was there.

本発明者らは上記課題に鑑み鋭意検討を続けてきた。その結果、斯様にFZ法により得たシリコン単結晶棒における最終固化部を分析試料としても、その分析感度が十分に高くならない理由は、該最終固化部からの金属の抽出が、これをフッ硝酸水溶液に浸漬することにより行われていることによる知見を得た。即ち、フッ硝酸水溶液にも金属不純物が含有されているところ、上記最終固化部を形成するシリコン単結晶を分解するためには、相当量のフッ硝酸水溶液に浸漬しなければならず、それにより金属不純物の外的汚染が発生し、前記高感度の分析を困難にしていることが主原因であった。そして、この知見をもとに、前記最終固化部からの金属不純物の抽出について、該最終固化部をシリコンの分解性蒸気に晒すことにより行えば、上記外的汚染は大幅に抑制できることを見出し、本発明を完成するに至った。 The present inventors have continued diligent studies in view of the above problems. As a result, even if the final solidified portion of the silicon single crystal ingot obtained by the FZ method is used as the analysis sample, the reason why the analysis sensitivity is not sufficiently high is that the extraction of the metal from the final solidified portion causes the We obtained the knowledge that this was done by immersing in a nitric acid aqueous solution. That is, when the hydrofluoric/nitric acid aqueous solution also contains metal impurities, in order to decompose the silicon single crystal forming the final solidified portion, it must be immersed in a considerable amount of hydrofluoric/nitric acid aqueous solution. The main cause was that external contamination of impurities occurred, making it difficult to perform the high-sensitivity analysis. Then, based on this knowledge, regarding the extraction of metal impurities from the final solidified portion, if the final solidified portion is exposed to decomposable vapor of silicon, it is found that the external contamination can be significantly suppressed, The present invention has been completed.

即ち、本発明は、多結晶シリコン中に含まれる金属不純物濃度を測定する方法であって、測定対象の多結晶シリコンを用いてFZ法により単結晶成長させ、得られたシリコン単結晶棒から最終固化部を採取し、次いで、該最終固化部をシリコンの分解性蒸気に晒して分解残渣を得た後、これを回収液に溶解させ金属量を測定し、前記測定対象の多結晶シリコンの濃度に換算する、ことを特徴とする多結晶シリコン中の金属不純物分析方法である。 That is, the present invention is a method for measuring the concentration of metal impurities contained in polycrystalline silicon, in which the polycrystalline silicon to be measured is used to grow a single crystal by the FZ method, and the final silicon single crystal rod is obtained. The solidified portion is sampled, and then the final solidified portion is exposed to decomposable vapor of silicon to obtain a decomposition residue, which is dissolved in a recovery liquid to measure the amount of metal, and the concentration of the polycrystalline silicon to be measured. The method for analyzing metal impurities in polycrystalline silicon is characterized in that

本発明によれば、多結晶シリコン中に含まれる金属不純物を、外部汚染の影響を抑制して、高感度且つ高精度で分析することが可能になる。 According to the present invention, metal impurities contained in polycrystalline silicon can be analyzed with high sensitivity and high accuracy while suppressing the influence of external contamination.

図1は、本発明において、FZ法により得たシリコン単結晶棒から採取した最終固化部を、シリコンの分解性蒸気(フッ硝酸蒸気)に晒す代表的態様を示す模式図である。FIG. 1 is a schematic diagram showing a typical embodiment in which the final solidified portion collected from a silicon single crystal ingot obtained by the FZ method is exposed to decomposable vapor of silicon (fluorine nitric acid vapor) in the present invention. 図2は、FZ法によりシリコン単結晶棒を得る方法の代表的態様を示す模式図である。FIG. 2 is a schematic view showing a typical embodiment of a method for obtaining a silicon single crystal ingot by the FZ method. 図3は、FZ法により製造したシリコン単結晶棒の状態を示す模式図である。FIG. 3 is a schematic diagram showing a state of a silicon single crystal ingot manufactured by the FZ method.

本発明において、金属不純物量を分析する多結晶シリコンは、特に制限されるものではなく、通常は、シーメンス法により製造された多結晶シリコンロッドの直胴部から、析出心を含んで直径方向に切出した多結晶シリコン棒が対象になる。即ち、この多結晶シリコン棒に含まれる金属量を分析することにより、これを切出したシーメンス法による多結晶シリコンロッドの金属不純物量を求めることができる。ここで、シーメンス法とは、トリクロロシランやモノシラン等のシラン原料ガスを、加熱されたシリコン芯線に接触させることにより、当該シリコン芯線の表面に多結晶シリコンをCVD(Chemical Vapor Deposition)法により気相成長(析出)させる方法である。 In the present invention, the polycrystalline silicon for analyzing the amount of metal impurities is not particularly limited, and is usually from the straight body portion of the polycrystalline silicon rod manufactured by the Siemens method to the diametrical direction including the precipitation core. The cut polycrystalline silicon rod is the target. That is, by analyzing the amount of metal contained in this polycrystalline silicon rod, the amount of metal impurities in the polycrystalline silicon rod obtained by cutting out this polycrystalline silicon rod can be determined. Here, the Siemens method, silane source gas such as trichlorosilane or monosilane, by contacting the heated silicon core wire, the polycrystalline silicon on the surface of the silicon core wire by CVD (Chemical Vapor Deposition) method by vapor phase This is a method of growing (precipitating).

斯様に多結晶シリコンロッドの直胴部から切出す多結晶シリコン棒の直径は、一般には15〜25mmの範囲から採択すれば良いが、「電子情報技術産業情報規格JEITA EM-3601A 高純度多結晶シリコン標準品規格」に従って、19±1mmであるのが特に好ましい。 As described above, the diameter of the polycrystalline silicon rod cut out from the straight body portion of the polycrystalline silicon rod may be generally selected from the range of 15 to 25 mm. However, "Electronic Information Technology Industrial Information Standard JEITA EM-3601A High Purity Poly According to the "Crystalline Silicon Standard Standard", 19±1 mm is particularly preferable.

また、測定対象の多結晶シリコンは、前記棒状ではなく、粒状であっても、これを筒体に充填して、これを円周方向から帯状に加熱して少なくとも一部の粒状多結晶シリコンを溶融焼結により一体化させることにより、多結晶シリコン棒を形成させることで、前記FZ法による単結晶成長に適用することができる。この手法の概略は例えば特開平11−304791号公報に記載の方法等に準じて実施すれば良い。筒体の材質は非電導性であればよいが、通常は、アルミナ、シリカ、窒化珪素等のセラミックが使用される。特に、内部が透視可能である事の理由から、透明石英ガラスが好適に使用される。 Further, even if the polycrystalline silicon to be measured is not in the rod shape but in a granular shape, the cylindrical body is filled with this and at least a part of the granular polycrystalline silicon is heated in a band shape from the circumferential direction. By forming a polycrystalline silicon rod by melting and integrating it, it can be applied to the single crystal growth by the FZ method. The outline of this method may be carried out in accordance with, for example, the method described in JP-A No. 11-304791. The material of the cylindrical body may be non-conductive, but ceramics such as alumina, silica and silicon nitride are usually used. In particular, transparent quartz glass is preferably used because the inside can be seen through.

粒状多結晶シリコンとしては、前記シーメンス法により製造された多結晶シリコンロッドの破砕物や、流動床反応により得た粒状多結晶シリコン等が挙げられる。粒状多結晶シリコンの粒径は、長径で示して0.1〜10mm、特に1〜5mmであるのが、操作性の良さから好ましい。 Examples of granular polycrystalline silicon include crushed polycrystalline silicon rods produced by the Siemens method, granular polycrystalline silicon obtained by fluidized bed reaction, and the like. The particle size of the granular polycrystalline silicon is preferably 0.1 to 10 mm, particularly 1 to 5 mm in terms of major axis, from the viewpoint of good operability.

本発明の分析方法では、これら多結晶シリコンをFZ法により単結晶成長させ、シリコン単結晶棒を得る。FZ法はFloat-Zone法の略であり、原料多結晶を、高周波誘導加熱コイルを用いて部分的に加熱溶融しその溶融帯域を移動させることによって単結晶成長を行う方法である。その操作は、前記「JEITA EM-3601A」やこの規格が引用する「JIS H 0615 フォトルミネッセンスによるシリコン結晶中の不純物濃度測定方法」に記載の方法に準じれば良い。図2の斜視図により、FZ法によりシリコン単結晶棒を得る代表的態様を説明する。 In the analysis method of the present invention, these polycrystalline silicons are grown as single crystals by the FZ method to obtain silicon single crystal rods. The FZ method is an abbreviation for the Float-Zone method, and is a method for growing a single crystal by partially heating and melting a raw material polycrystal using a high-frequency induction heating coil and moving the melting zone. The operation may be based on the method described in the above “JEITA EM-3601A” or “JIS H 0615 Method for measuring impurity concentration in silicon crystal by photoluminescence” cited in this standard. A typical mode for obtaining a silicon single crystal ingot by the FZ method will be described with reference to the perspective view of FIG.

図2において、前記作成した多結晶シリコン棒9をその下端が高周波誘導加熱コイル10の近傍となるようにセットする。この高周波誘導加熱コイル10に高周波をかけて多結晶シリコン棒9の下端を誘導加熱を行うのに十分な温度になるまで加熱する。高周波が多結晶シリコン棒9の下端にかかると溶融する。なお、多結晶シリコン棒9の下端の加熱は、上記高周波誘導加熱コイル10により加熱する前に、カーボンヒーターにより予備加熱してもよい。 In FIG. 2, the polycrystalline silicon rod 9 prepared above is set so that its lower end is in the vicinity of the high frequency induction heating coil 10. A high frequency is applied to the high frequency induction heating coil 10 to heat the lower end of the polycrystalline silicon rod 9 to a temperature sufficient to perform induction heating. When a high frequency wave is applied to the lower end of the polycrystalline silicon rod 9, it melts. The lower end of the polycrystalline silicon rod 9 may be preheated by a carbon heater before being heated by the high frequency induction heating coil 10.

多結晶シリコン棒9の下端の加熱が行われた後、下方より種結晶11を移動させて多結晶シリコン棒9の下端に形成された溶融液に種結晶11の上端を漬けて溶融させる。種結晶11の上端が溶融した後、多結晶シリコン棒9と種結晶11を同時に下方に所定の速度、一般に1〜5mm/分で移動させることにより、多結晶シリコン棒9は下端から順次溶融し、種結晶11の上端には順次単結晶が成長する。 After the lower end of the polycrystalline silicon rod 9 is heated, the seed crystal 11 is moved from below to dip the upper end of the seed crystal 11 in the melt formed at the lower end of the polycrystalline silicon rod 9 to melt it. After the upper end of the seed crystal 11 is melted, the polycrystalline silicon rod 9 and the seed crystal 11 are simultaneously moved downward at a predetermined speed, generally 1 to 5 mm/min, so that the polycrystalline silicon rod 9 is sequentially melted from the lower end. A single crystal grows on the upper end of the seed crystal 11 in sequence.

図3で示すように、所定の長さ、例えば100〜300mmにシリコン単結晶12が成長した後、多結晶シリコン棒9の下方への移動を止め、上部に移動させることで多結晶シリコン棒9とシリコン単結晶12との間に形成されている溶融液を切り、切れる直前に多結晶シリコン棒9と単結晶との間に形成されていた溶融液は単結晶上端に保持され、その後固化させて、いわゆる最終固化部4が得られる。切れる直前に多結晶シリコン棒9とシリコン単結晶12との間に形成されている溶融液量が所定の量、一般に直径とほぼ同じ高さの三角錐形となるように、多結晶シリコン棒9とシリコン単結晶12との間に形成されている溶融液を切る前に高周波の出力を予め調整する。 As shown in FIG. 3, after the silicon single crystal 12 has grown to a predetermined length, for example, 100 to 300 mm, the polycrystalline silicon rod 9 is stopped from moving downward and is moved upward to move the polycrystalline silicon rod 9 to the upper side. The molten liquid formed between the silicon single crystal 12 and the silicon single crystal 12 is cut, and the molten liquid formed between the polycrystalline silicon rod 9 and the single crystal immediately before the cutting is held at the upper end of the single crystal and then solidified. Thus, a so-called final solidification part 4 is obtained. The polycrystalline silicon rod 9 is formed so that the amount of the molten liquid formed between the polycrystalline silicon rod 9 and the silicon single crystal 12 immediately before the cutting becomes a predetermined amount, generally a triangular pyramid having almost the same height as the diameter. Before cutting the melt formed between the silicon single crystal 12 and the silicon single crystal 12, the high frequency output is adjusted in advance.

こうしたFZ法によるシリコン単結晶棒の製造は、清浄な不活性ガス雰囲気下で行うのが好ましく、得られたシリコン単結晶棒は、清浄な不活性ガス下か、真空状態で保管するのが好ましい。 The production of the silicon single crystal ingot by the FZ method is preferably carried out in a clean inert gas atmosphere, and the obtained silicon single crystal ingot is preferably stored under a clean inert gas or in a vacuum state. ..

上記FZ法に供するに際して、測定対象の多結晶シリコンは、表面の金属汚染を排除するため、直前に表面洗浄するのが好ましい。この表面洗浄は、例えば、フッ硝酸水溶液によるエッチング洗浄後、超純水にてリンスし、清浄ガスでブローする方法が挙げられる。また、こうした表面洗浄の別法は、前記JIS H 0615でも規定されている。表面が清浄化された多結晶シリコンは、FZ化までの待機中において、清浄な不活性ガス下か、真空状態で保管するのが好ましい。 In subjecting the polycrystalline silicon to be measured to the above-mentioned FZ method, it is preferable to clean the surface immediately before, in order to eliminate metal contamination on the surface. Examples of the surface cleaning include a method of performing etching cleaning with a hydrofluoric nitric acid aqueous solution, rinsing with ultrapure water, and blowing with a clean gas. Another method of surface cleaning is also specified in JIS H 0615. The polycrystalline silicon whose surface has been cleaned is preferably stored under a clean inert gas or in a vacuum state while waiting until FZ conversion.

FZ法は、可能な限り実施時に不純物の汚染を受けない方法で実施するのが望ましい。この観点から、前記高周波誘導加熱コイルは、銀製コイルを用いるのが好適である。即ち、FZ法において、多結晶体を環囲して設置される高周波誘導加熱コイルは、内空に挿入されるシリコン単結晶棒を汚染しやすい。この際、該高周波誘導加熱コイルが、汎用されている銅製等であると、銅は後述するように多結晶シリコンにおいて極力汚染を避けたい金属であるため望ましくない。これに対して、係る高周波誘導加熱コイルを、銀製(特に純度が99.99質量%以上の純銀製)にした場合には、こうした有害性の高い金属による外的汚染が抑制されて好ましい。高周波誘導加熱コイルを収容するFZ炉内は、清浄な不活性ガスを常時フローしておくのが好ましい。また、多結晶シリコンの溶融中は、炉の出口測定において、0.5μm以上の粒子数を、2.8L中100個以下にするのが好ましい。 It is desirable that the FZ method is carried out as much as possible without being contaminated with impurities. From this viewpoint, it is preferable to use a silver coil for the high frequency induction heating coil. That is, in the FZ method, the high-frequency induction heating coil installed around the polycrystalline body is likely to contaminate the silicon single crystal rod inserted in the inner space. At this time, if the high-frequency induction heating coil is made of commonly used copper or the like, it is not desirable because copper is a metal that is desired to avoid contamination in polycrystalline silicon as described later. On the other hand, when the high frequency induction heating coil is made of silver (particularly, pure silver having a purity of 99.99% by mass or more), external contamination by such a highly harmful metal is suppressed, which is preferable. It is preferable to constantly flow a clean inert gas in the FZ furnace that houses the high frequency induction heating coil. Further, during the melting of the polycrystalline silicon, it is preferable that the number of particles of 0.5 μm or more is 100 or less in 2.8 L in the measurement at the outlet of the furnace.

また、シリコン単結晶棒の最終固化部は、最終溶融帯を単結晶側に残し、上部の多結晶はすみやかに切り離して製造するのが好適である。斯様にしてFZ法により得られたシリコン単結晶棒において、最終固化部には、金属不純物が偏析によって濃縮されている。このことから本発明では、シリコン単結晶棒から該最終固化部を分離し、ここに含有される金属量を測定することにより、測定対象の多結晶シリコンに含まれる金属不純物量を求める。 Further, it is preferable that the final solidified portion of the silicon single crystal ingot is manufactured by leaving the final molten zone on the single crystal side and immediately separating the upper polycrystal. In the silicon single crystal ingot thus obtained by the FZ method, metal impurities are concentrated in the final solidified portion by segregation. Therefore, in the present invention, the final solidified portion is separated from the silicon single crystal ingot, and the amount of metal contained therein is measured to obtain the amount of metal impurities contained in the polycrystalline silicon to be measured.

ここで、シリコン単結晶棒からの最終固化部の分離は、適宜に実施すれば良いが、例えば金属刃を用いての切断は切断面の金属汚染を引き起こす。このため、樹脂製ハンマーによる打撃で採取するのが好ましい。打撃を行う載置台も、外的汚染の低減のため、載置面がシリコン製、特に、多結晶シリコン製であるのが好ましい。これらハンマー、載置台は、適宜、エッチング洗浄してから供するのが望ましい。 Here, the separation of the final solidified portion from the silicon single crystal rod may be appropriately performed, but cutting with a metal blade, for example, causes metal contamination of the cut surface. For this reason, it is preferable to collect by hitting with a resin hammer. It is preferable that the mounting table to be hit also has a mounting surface made of silicon, particularly polycrystalline silicon, in order to reduce external contamination. It is desirable that the hammer and the mounting table are appropriately cleaned by etching before use.

最終固化部の採取量は、シリコン単結晶棒全体重量の0.1質量%〜5質量%、特に0.5質量%〜3質量%とするが好ましい。最終固化部を0.1質量%未満では、その部分が微小になるため、採取の操作性が悪くなり、5質量%以上となると、分解時の操作性が悪化するため、多結晶中の不純物量の定量には好ましくない。採取した最終固化部は、フッ酸、塩酸、過酸化水素の酸またはこれらの混酸で洗浄することにより、最表面の付着汚染のみを除去し、次工程に供するのが好ましい。 The amount of the final solidified portion collected is preferably 0.1% by mass to 5% by mass, and particularly preferably 0.5% by mass to 3% by mass of the total weight of the silicon single crystal ingot. If the final solidified portion is less than 0.1% by mass, the portion becomes minute, so that the operability of sampling is deteriorated, and if it is 5% by mass or more, the operability at the time of decomposition is deteriorated, and therefore impurities in the polycrystal are impaired. Not suitable for quantitative determination. It is preferable that the collected final solidified portion is washed with hydrofluoric acid, hydrochloric acid, an acid of hydrogen peroxide or a mixed acid thereof to remove only the attached contamination on the outermost surface and to be subjected to the next step.

斯様にして採取した最終固化部は、これを構成するシリコン単結晶を分解して金属不純物を回収し、その量を分析する。本発明は、この最終固化部からの金属不純物の回収について、該最終固化部をシリコンの分解性蒸気に晒すことでこれを行う点に最大の特徴を有する。斯様にして分解性蒸気に晒すことで、シリコン単結晶は分解して分解残渣が得られ、これを回収液に溶解させて、その金属量を測定する。 The final solidified portion thus collected decomposes the silicon single crystal that constitutes it to recover metal impurities, and analyzes the amount thereof. The present invention has the greatest feature in recovering the metal impurities from the final solidified portion by exposing the final solidified portion to a decomposable vapor of silicon. By thus exposing to decomposable vapor, the silicon single crystal is decomposed to obtain a decomposition residue, which is dissolved in the recovery liquid and the amount of the metal is measured.

即ち、前記従来技術のように最終固化部を、シリコンの分解液(代表的にはフッ硝酸水溶液)に浸漬して実施したのでは、使用する分解性液には、これが高純度品であっても相当量の金属不純物が含有されており、これが影響し、最終固化部に含有される微量金属の分析を困難にしている。これに対して、上記の如くにシリコンの分解性蒸気を使用する態様にすれば、たとえ該蒸気の発生源液には金属不純物がある程度に含有されていても、これから発生する蒸気に同伴する量は微少に抑えることができるため、最終固化部に含有される金属不純物の測定に際して、外的汚染の影響を大幅に低減できる。 That is, as in the prior art, the final solidification part was immersed in a silicon decomposing solution (typically, a hydrofluoric nitric acid solution), and the decomposing solution used was a high-purity product. Also contains a considerable amount of metal impurities, which affects the analysis of trace metals contained in the final solidified part. On the other hand, in the case where the decomposable vapor of silicon is used as described above, even if the source liquid of the vapor contains a certain amount of metal impurities, the amount that accompanies the vapor generated from the vapor Since it can be suppressed to a very small amount, the influence of external contamination can be greatly reduced when measuring the metal impurities contained in the final solidified portion.

ここで、シリコンの分解性蒸気としては、具体的には、フッ硝酸、フッ化水素酸、フッ化アンモニウム、王水等の酸溶液の蒸気が挙げられ、特に、好ましくはフッ硝酸蒸気である。フッ硝酸蒸気としては、フッ酸が15〜25質量%、硝酸が30〜40質量%となる混合液を沸点以下60〜90℃に加熱して発生させるのがよく、より好ましくは電子工業用以上の純度があるものを、フッ酸18〜22質量%、硝酸34〜38質量%に混合した液を、ホットプレートなどの加熱媒体上で加熱して得られる蒸気が、シリコンの分解性に特に優れるため好ましい。また蒸気割合として、フッ酸及び硝酸の合計質量に対し、フッ酸が50〜70質量%となるのが好ましい。 Specific examples of the decomposable vapor of silicon include vapors of acid solutions such as hydrofluoric nitric acid, hydrofluoric acid, ammonium fluoride, and aqua regia, and hydrofluoric nitric acid vapor is particularly preferable. The hydrofluoric/nitric acid vapor is preferably generated by heating a mixed solution containing 15 to 25% by mass of hydrofluoric acid and 30 to 40% by mass of nitric acid at a boiling point of 60 to 90°C, more preferably for the electronic industry or more. Which has a purity of 18 to 22% by mass of hydrofluoric acid and 34 to 38% by mass of nitric acid is heated on a heating medium such as a hot plate to obtain a vapor, which is particularly excellent in decomposability of silicon. Therefore, it is preferable. Further, the vapor ratio is preferably 50 to 70 mass% with respect to the total mass of hydrofluoric acid and nitric acid.

外気からの汚染の少なさを勘案すれば、最終固化部はその分解用の密閉容器中に納め、上記分解性蒸気も、係る密閉容器中で発生させて最終固化部に作用させるのが好ましい。こうした密閉容器を用いて、最終固化部をシリコンの分解性蒸気に晒す代表的態様を図1により説明する。この態様においてシリコンの分解性蒸気は、フッ硝酸蒸気が使用される。 Considering the small amount of pollution from the outside air, it is preferable that the final solidification part is placed in a closed container for its decomposition, and the decomposable vapor is also generated in the closed container to act on the final solidification part. A typical mode of exposing the final solidified portion to a decomposable vapor of silicon using such a closed container will be described with reference to FIG. In this embodiment, hydrofluoric nitric acid vapor is used as the decomposable vapor of silicon.

図1において、最終固化部分解用密閉容器1は、上部が開口する容器本体2と、この開口部に被せる密閉用蓋3とからなり、容器本体2の中央に、ビーカー載置台8が設けられ、その上に最終固化部4が納められたビーカー5が載置されている。そして、容器本体2の底部には、フッ硝酸水溶液6がビーカー5より低い位置に収容されている。また、密閉用蓋3の天井は、付着した分解性蒸気の凝縮滴のビーカー5内への落滴を防止するために、傘状(円錐状)に傾斜しているのが好ましい。この密閉容器1をホットプレート7上に置き、前記フッ硝酸蒸気を発生させる好適温度に加熱することにより、密閉容器1内にフッ硝酸蒸気を充満させ、ビーカー5内に納められた最終固化部4におけるシリコンの分解を行えば良い。 1, a closed container 1 for decomposing the final solidified portion is composed of a container body 2 having an opening at the top and a lid 3 for covering the opening, and a beaker mounting table 8 is provided at the center of the container body 2. , A beaker 5 in which the final solidification part 4 is housed is placed on it. Then, the hydrofluoric nitric acid aqueous solution 6 is accommodated at a position lower than the beaker 5 at the bottom of the container body 2. Further, the ceiling of the lid 3 for sealing is preferably inclined in an umbrella shape (conical shape) in order to prevent condensed droplets of the attached decomposable vapor from dropping into the beaker 5. The closed container 1 is placed on a hot plate 7 and heated to a suitable temperature for generating the hydrofluoric nitric acid vapor, so that the closed container 1 is filled with the hydrofluoric nitric acid vapor, and the final solidification section 4 stored in the beaker 5 is filled. It suffices to disassemble the silicon in.

密閉容器の材質は耐酸性で、かつ耐圧性を有する物が好ましく、四フッ化エチレン樹脂(PTFE)や四フッ化エチレンとパーフルオロアルコキシエチレンとの共重合樹脂(PFA)等のフッ素樹脂製が好ましい。分解性蒸気に最終固化部を晒す時間は、該最終固化部を構成するシリコン単結晶を十分に分解するだけの時間が求められ、一般には10〜50時間から採択される。 The material of the closed container is preferably acid resistant and pressure resistant, and is made of fluororesin such as tetrafluoroethylene resin (PTFE) or a copolymer resin of tetrafluoroethylene and perfluoroalkoxyethylene (PFA). preferable. The time for exposing the final solidified portion to the decomposable vapor is required to sufficiently decompose the silicon single crystal forming the final solidified portion, and is generally selected from 10 to 50 hours.

斯様にして最終固化部を構成するシリコン単結晶を分解することにより、ビーカー5内には、最終固化部に含有されていた金属不純物が濃縮された分解残渣が生ずる。得られた分解残滓は、加熱乾固してから、回収液への溶解に供するのが好ましい。なお、分解残滓に白色固体が含有される場合があるが、この際には、分解前あるいは後に、硫酸や王水を添加して乾固することで抑制し、測定装置への回収液の導入量変動を防止でき好ましい。 By decomposing the silicon single crystal forming the final solidified portion in this manner, a decomposition residue in which the metal impurities contained in the final solidified portion are concentrated is generated in the beaker 5. The obtained decomposition residue is preferably heated to dryness and then subjected to dissolution in the recovered liquid. White solids may be contained in the decomposition residue, but in this case, before or after decomposition, it is suppressed by adding sulfuric acid or aqua regia to dryness, and the collected liquid is introduced into the measuring device. It is preferable because it can prevent fluctuation in the amount.

分解残滓を溶解する回収液としては、硝酸、塩酸、王水、硫酸等が挙げられ、特に、高純度品が入手できる硫酸が好適である。酸の濃度は、分解残滓を溶解する良好さから0.05〜0.3質量%であるのが好ましい。溶解は、分解残滓の放冷後に行い、ピペット等で精確に回収液量を量り取る。回収液量は、金属の測定に必要量で十分で、一般には、
100〜500μlが好ましい。
Examples of the recovery liquid for dissolving the decomposition residue include nitric acid, hydrochloric acid, aqua regia, sulfuric acid, and the like, and sulfuric acid, which is a highly purified product, is particularly preferable. The concentration of the acid is preferably 0.05 to 0.3 mass% from the viewpoint of good dissolution of the decomposition residue. Dissolution is performed after the decomposition residue is allowed to cool, and the amount of the recovered liquid is accurately measured using a pipette or the like. The amount of recovered liquid is sufficient for the measurement of metals, and in general,
100 to 500 μl is preferable.

金属量の分析法は、特に制限されるものではないが、通常、原子吸光法または誘導結合プラズマ質量分析法が適用される。これらの分析法における具体的な測定操作は、それぞれ常法に従えばよい。得られた測定値をもとに、測定対象の多結晶シリコンの金属不純物濃度を計算する。その方法は、
濃度(pptw)=(最終固化部からの測定値−操作ブランク)(pg/ml)×回収液(ml)÷ シリコン単結晶棒の全体重量(g)
によれば良い。ここで、上記操作ブランクは、最終固化部の分解残滓を溶解させない回収液を用いて、金属量を測定した対照試験の測定値である。
The metal content analysis method is not particularly limited, but an atomic absorption method or an inductively coupled plasma mass spectrometry method is usually applied. Specific measuring operations in these analytical methods may be carried out according to ordinary methods. The metal impurity concentration of the polycrystalline silicon to be measured is calculated based on the obtained measured values. The method is
Concentration (pptw) = (measured value from final solidification part-operation blank) (pg/ml) x recovery liquid (ml) / total weight of silicon single crystal rod (g)
According to Here, the above-mentioned operation blank is a measured value of a control test in which the amount of metal was measured using a recovery liquid which did not dissolve the decomposition residue of the final solidified portion.

多結晶シリコンにおいて、測定する金属不純物は、偏析係数が小さいほど好ましく、例えば偏析係数が1より小さい元素であれば特に好ましい。これらの元素としては、Li,Cu,Ag,Au,Zn,Cd,Cr,Al,Ga,In,Th,Sn,As,Bi,
Mg,Fe,Co,Ni,Ta,Ti等が挙げられ、特に、電気的特性への影響の理由から、Cu、Ni、Feから選ばれる少なくとも1種であるのが好ましい。このうちCuは、シリコンにおいて拡散が非常に速い理由から、その低減化が強く要求される元素であり、本発明の測定方法での高感度化の効果も顕著であり、特に好ましい。
In polycrystalline silicon, the smaller the segregation coefficient of the metal impurities to be measured, the more preferable. For example, the element having the segregation coefficient of less than 1 is particularly preferable. These elements include Li, Cu, Ag, Au, Zn, Cd, Cr, Al, Ga, In, Th, Sn, As, Bi,
Examples thereof include Mg, Fe, Co, Ni, Ta, and Ti, and in particular, at least one selected from Cu, Ni, and Fe is preferable for the reason of affecting the electrical characteristics. Of these, Cu is an element that is strongly required to be reduced because it diffuses very rapidly in silicon, and the effect of increasing the sensitivity in the measuring method of the present invention is remarkable, and is particularly preferable.

多結晶シリコンの定量限界は一般的には、Fe,Ni,Cuであれば10ppbw以下であり、細心の注意をはらって行う場合には100pptwも可能である。 The limit of quantification of polycrystalline silicon is generally 10 ppbw or less for Fe, Ni, and Cu, and 100 pptw is possible if it is performed with great care.

本発明を更に具体的に説明するため以下の実施例を挙げて説明するが本発明はこれらの実施例に限定されるものではない。 The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

実施例1
トリクロロシランを原料ガスにシーメンス法により製造した多結晶シリコンロッドの直胴部の長さ方向の任意の位置から、内径19±1mmのコアードリルによって,析出心を含む直径方向にFZ用の多結晶シリコン棒を切り出した。切り出した、長さ120mmの多結晶シリコン棒の表面を、各電子工業用の、50質量%のフッ酸10ml、61質量%硝酸40mlを混合したフッ硝酸水溶液でエッチングした後、金属不純物が1pptw以下の超純水でリンスした。多結晶シリコン棒上の水滴をArガスによってブロー後、真空デシケータ内で吸引させ、FZ法によるシリコン単結晶棒の製造の直前まで保管した。
Example 1
Polycrystalline silicon for FZ in a diameter direction including a deposition core by a core drill having an inner diameter of 19±1 mm from an arbitrary position in the length direction of the straight body portion of the polycrystalline silicon rod manufactured by the Siemens method using trichlorosilane as a raw material gas. I cut out a stick. The surface of the cut out polycrystalline silicon rod having a length of 120 mm was etched with a hydrofluoric nitric acid aqueous solution for each electronics industry containing 10 ml of hydrofluoric acid of 50% by mass and 40 ml of 61% by mass of nitric acid, and then metal impurities were 1 pptw or less. Rinse with ultrapure water. The water droplets on the polycrystalline silicon rod were blown with Ar gas, sucked in a vacuum desiccator, and stored until just before the production of the silicon single crystal rod by the FZ method.

FZ法によるシリコン単結晶棒の製造装置として、高周波誘導加熱コイルが純銀製のものを使用した。この製造装置を用いて、前記多結晶シリコンロッドから切り出した多結晶シリコン棒を原料に、FZ法によるシリコン単結晶棒の製造を実施した。具体的には、まず、多結晶シリコン棒をその下端が高周波誘導加熱コイルの面内に入る様にセットした。加熱の初期においては、高周波誘導加熱コイルでカーボン板を7.5KWの出力(周波数は2MHz)で加熱し、カーボン板からの放射熱により棒状シリコンが誘導加熱を行うのに充分な温度になるまで多結晶シリコン棒を放射加熱した。高周波が多結晶シリコン棒にかかったことを確認した後、カーボン板を取り去り、同時に高周波出力を7KWから4KWに下げ、多結晶シリコン棒の下端10mmが溶融状態になるようにした。下方より長さ75mm、一辺が3.5mm角の種単結晶を移動させて、その上端を多結晶シリコン棒の下端に形成された溶融液に漬けて溶融させ、多結晶シリコン棒と種単結晶が溶融液を介して結合状態になるようにした。 A high-frequency induction heating coil made of pure silver was used as an apparatus for manufacturing a silicon single crystal ingot by the FZ method. Using this manufacturing apparatus, a polycrystalline silicon rod cut out from the polycrystalline silicon rod was used as a raw material to fabricate a silicon single crystal rod by the FZ method. Specifically, first, a polycrystalline silicon rod was set so that its lower end was in the plane of the high frequency induction heating coil. In the initial stage of heating, the carbon plate is heated with a high-frequency induction heating coil at an output of 7.5 KW (frequency is 2 MHz), and the radiant heat from the carbon plate heats the rod-shaped silicon to a temperature sufficient for induction heating. The polycrystalline silicon rod was radiantly heated. After confirming that the high frequency was applied to the polycrystalline silicon rod, the carbon plate was removed, and at the same time, the high frequency output was lowered from 7 KW to 4 KW so that the lower end 10 mm of the polycrystalline silicon rod was in a molten state. A seed single crystal having a length of 75 mm and a side of 3.5 mm square is moved from below, and the upper end of the seed single crystal is immersed in a melt formed at the lower end of the polycrystalline silicon rod to be melted. Was allowed to be bound via the melt.

上記の状態を作った後、多結晶シリコン棒と種結晶をそれぞれ2mm/分、5mm/分の速度で同時に下方に移動させ、加熱域を相対的に上昇させた。加熱域の移動中は、溶融液量が変化しないように高周波出力を4.5KWに維持した。多結晶シリコン棒の溶融中、FZ炉内は清浄なアルゴンガスを20L/minで常時フローし、炉の出口測定において、0.5μm以上の粒子数が、2.8L中50個以下に維持した。こうして種結晶の上方に長さが100mmの単結晶を成長された後、高周波出力を4KWから2.5KWに下げ、溶融液量を減少させた後、シリコン単結晶棒の下方への移動を止め、シリコン単結晶棒と単結晶との間に形成されている溶融液を切り、切れる直前にシリコン単結晶棒と単結晶との間に形成されていた溶融液を単結晶上端に保持させ、その後固化させて、いわゆる最終固化部を作製後、炉内で放冷し、直径12mm、長さ220mm、50.2gのシリコン単結晶棒を作製した。 After the above state was created, the polycrystalline silicon rod and the seed crystal were simultaneously moved downward at a speed of 2 mm/min and 5 mm/min, respectively, to relatively raise the heating area. During the movement of the heating zone, the high frequency output was maintained at 4.5 kW so that the amount of the melt did not change. During the melting of the polycrystalline silicon rod, a clean argon gas was constantly flowed at 20 L/min in the FZ furnace, and the number of particles of 0.5 μm or more was maintained at 50 or less in 2.8 L in the measurement of the outlet of the furnace. .. After growing a single crystal with a length of 100 mm above the seed crystal in this way, the high-frequency output was reduced from 4 KW to 2.5 KW to reduce the melt volume, and then the downward movement of the silicon single crystal rod was stopped. , Cutting the molten liquid formed between the silicon single crystal rod and the single crystal, and holding the molten liquid formed between the silicon single crystal rod and the single crystal immediately before the cutting, at the upper end of the single crystal, After solidifying and producing a so-called final solidified portion, it was allowed to cool in a furnace to produce a silicon single crystal ingot having a diameter of 12 mm, a length of 220 mm and 50.2 g.

次いで、このシリコン単結晶棒について、その最終固化部0.5gを、多結晶シリコン台上で、テフロン(登録商標)製ハンマーで打撃して分離し採取した。この最終固化部の表面を、5質量%フッ酸、5質量%塩酸、5質量%過酸化水素の混合溶液で洗浄し、金属不純物が1pptw以下の超純水でリンスした後、前述の図1に示しした最終固化部分解用の密閉容器1のビーカー5内に納めた。さらに、容器本体2の底部には、各電子工業用の、50質量%フッ酸50ml、61質量%硝酸70mlを入れた後、容器本体2の上面開口部を密閉用蓋3により遮蔽し、密閉容器1を140℃に設定したホットプレート上に載置した。 Next, 0.5 g of the final solidified portion of this silicon single crystal ingot was hit by a hammer made of Teflon (registered trademark) on a polycrystalline silicon table, separated and collected. The surface of this final solidified portion was washed with a mixed solution of 5% by mass hydrofluoric acid, 5% by mass hydrochloric acid, and 5% by mass hydrogen peroxide, and rinsed with ultrapure water having metal impurities of 1 pptw or less, and then the above-mentioned FIG. It was placed in the beaker 5 of the closed container 1 for decomposing the final solidified portion shown in FIG. Further, after putting 50 ml of hydrofluoric acid 50 ml and 61 wt% nitric acid 70 ml for each electronics industry into the bottom of the container body 2, the top opening of the container body 2 is shielded by the lid 3 for sealing. The container 1 was placed on a hot plate set at 140°C.

これにより、密閉容器1内はフッ硝酸蒸気が充満し、ビーカー5内の最終固化部は該フッ硝酸蒸気に晒され、分解が進行した。この分解操作を24時間継続し、容器本体2の底部に分解残渣を得た。ビーカー5をさらにホットプレート上で加熱、乾固した後放冷した。 As a result, the closed container 1 was filled with hydrofluoric nitric acid vapor, and the final solidified portion in the beaker 5 was exposed to the hydrofluoric nitric acid vapor, and the decomposition proceeded. This decomposition operation was continued for 24 hours, and a decomposition residue was obtained at the bottom of the container body 2. The beaker 5 was further heated on a hot plate to dryness and then left to cool.

放冷後、ビーカー5底の分解残渣を、0.1質量%硫酸からなる回収液0.5mlに溶解させ回収した。この回収液中の、Cu、Ni、及びFeの各金属元素の濃度を、誘導結合プラズマ質量分析計によって測定した。なお、併せて、密閉容器1のビーカー5内に何も収容しないで同様に実施して、Cu、Ni、及びFeの各金属元素の濃度を測定するブランク測定も5回実施し、得られる測定値の10σから、それぞれの金属元素での定量下限値を求めた。 After cooling, the decomposition residue at the bottom of the beaker 5 was dissolved in 0.5 ml of a recovery liquid containing 0.1% by mass sulfuric acid and recovered. The concentration of each metal element of Cu, Ni, and Fe in this recovered liquid was measured by an inductively coupled plasma mass spectrometer. In addition, in addition, a blank measurement for measuring the concentration of each metal element of Cu, Ni, and Fe was also performed 5 times by performing the same without containing anything in the beaker 5 of the closed container 1, and the obtained measurement The lower limit of quantification for each metal element was determined from the value of 10σ.

以上の分析結果から、下記計算
濃度(pptw)=(最終固化部からの測定値−操作ブランク)(pg/ml)×回収液(ml)÷ シリコン単結晶棒の全体重量(g)
により、多結晶シリコンロッドから切り出した多結晶シリコン棒に含まれる金属不純物の濃度を求めた。結果を表1に示した。
From the above analysis results, the following calculated concentration (pptw)=(measured value from final solidification part−operation blank) (pg/ml)×recovered liquid (ml)÷total weight of silicon single crystal rod (g)
Thus, the concentration of metal impurities contained in the polycrystalline silicon rod cut out from the polycrystalline silicon rod was obtained. The results are shown in Table 1.

比較例1
実施例1において、最終固化部分解用密閉容器1として、容器本体2の底部中央にビーカー保持台8が設けられておらず、ビーカー5も設置されていないものを用い、FZ法シリコン単結晶棒から採取した最終固化部を、容器本体2の底部に直接収容し、容器本体2の底部に入れたフッ硝酸水溶液(各電子工業用の50質量%フッ酸50ml、61質量%硝酸70mlの混酸)に浸漬し、該最終固化部の分解を行う以外、上記実施例1と同様に実施して、多結晶シリコンロッドから切り出した多結晶シリコン棒に含まれる金属不純物の濃度を求めた。結果を表1に併せて示した。
Comparative Example 1
In Example 1, as the closed container 1 for decomposing the final solidified portion, one in which the beaker holding table 8 was not provided in the center of the bottom of the container body 2 and the beaker 5 was not installed was used. The final solidified part collected from was directly contained in the bottom of the container body 2, and the hydrofluoric nitric acid aqueous solution was put in the bottom of the container body 2 (50 mass% hydrofluoric acid 50 ml for each electronics industry, 61 mass% nitric acid 70 ml mixed acid) Was carried out in the same manner as in Example 1 except that the final solidified part was decomposed to determine the concentration of metal impurities contained in the polycrystalline silicon rod cut out from the polycrystalline silicon rod. The results are also shown in Table 1.

比較例2
実施例1において、多結晶シリコンロッドから切り出した多結晶シリコン棒のうち、析出心部を採取し、フッ硝酸で表面エッチングした0.5gを、ビーカー5の底部に直接収容し、上記実施例1と同様に密閉容器内で分解を実施する以外、実施例1と同様に操作した。得られた結果から、下記計算
濃度(pptw)=(多結晶シリコンの測定値−操作ブランク)(pg/ml)×回収液(ml)÷ 0.5(g)
により、多結晶シリコンロッドから切り出した多結晶シリコン棒に含まれる金属不純物の濃度を求めた。結果を表1に併せて示した。
Comparative example 2
In Example 1, out of the polycrystalline silicon rods cut out from the polycrystalline silicon rods, the precipitated core was sampled and 0.5 g surface-etched with hydrofluoric nitric acid was directly stored in the bottom of the beaker 5, and the above-mentioned Example 1 was used. The same operation as in Example 1 was carried out except that the decomposition was carried out in a closed container in the same manner as in. From the obtained results, the following calculated concentration (pptw)=(measured value of polycrystalline silicon−operation blank) (pg/ml)×recovered liquid (ml)÷0.5 (g)
Thus, the concentration of metal impurities contained in the polycrystalline silicon rod cut out from the polycrystalline silicon rod was obtained. The results are also shown in Table 1.

Figure 0006732595
Figure 0006732595

実施例2
金属不純物濃度を測定する多結晶シリコンロッドとして、夫々異なるロットA〜Cの3本を準備し、これらから切り出した多結晶シリコン棒に含まれるCu濃度を、実施例1と同様の方法により求めた。結果を表2に示した。
Example 2
As the polycrystalline silicon rods for measuring the concentration of metal impurities, three different lots A to C were prepared, and the Cu concentration contained in the polycrystalline silicon rods cut out from these rods was determined by the same method as in Example 1. .. The results are shown in Table 2.

Figure 0006732595
Figure 0006732595

1;最終固化部分解用密閉容器
2;容器本体
3;密閉用蓋
4;最終固化部
5;ビーカー
6;フッ硝酸水溶液
7;ホットプレート
8;ビーカー載置台
9;多結晶シリコン棒
10;高周波誘導加熱コイル
11;種結晶
12;シリコン単結晶
1; closed container for decomposing the final solidified part 2; container body 3; sealing lid 4; final solidified part 5; beaker 6; hydrofluoric nitric acid aqueous solution 7; hot plate 8; beaker mounting table 9; polycrystalline silicon rod 10; high frequency induction Heating coil 11; seed crystal 12; silicon single crystal

Claims (8)

多結晶シリコン中に含まれる金属不純物濃度を測定する方法であって、
測定対象の多結晶シリコンを用いてFZ法により単結晶成長させ、得られたシリコン単結晶棒から最終固化部を採取し、次いで、該最終固化部をシリコンの分解性蒸気に晒して分解残渣を得た後、これを回収液に溶解させ金属量を測定し、前記測定対象の多結晶シリコンの濃度に換算することを特徴とする多結晶シリコン中の金属不純物濃度測定方法。
A method for measuring the concentration of metal impurities contained in polycrystalline silicon,
A single crystal is grown by FZ method using polycrystalline silicon to be measured, a final solidified portion is collected from the obtained silicon single crystal rod, and then the final solidified portion is exposed to decomposable vapor of silicon to remove a decomposition residue. A method for measuring the concentration of metal impurities in polycrystalline silicon, which is characterized in that after obtaining it, it is dissolved in a recovery liquid to measure the amount of metal and converted into the concentration of the polycrystalline silicon to be measured.
シリコンの分解性蒸気が、フッ硝酸蒸気である、請求項1記載の多結晶シリコン中の金属不純物濃度測定方法。 The method for measuring the concentration of metal impurities in polycrystalline silicon according to claim 1, wherein the decomposable vapor of silicon is hydrofluoric nitric acid vapor. 測定対象の多結晶シリコンが、エッチング洗浄後超純水にてリンスされたものである、請求項1または請求項2記載の多結晶シリコン中の金属不純物濃度測定方法。 The method for measuring the concentration of metal impurities in polycrystalline silicon according to claim 1 or 2, wherein the polycrystalline silicon to be measured is rinsed with ultrapure water after etching and cleaning. エッチング洗浄に用いたエッチング液がフッ硝酸水溶液である、請求項3記載の結晶シリコン中の金属不純物濃度測定方法。 The method for measuring the concentration of metal impurities in crystalline silicon according to claim 3, wherein the etching solution used for etching cleaning is a hydrofluoric nitric acid aqueous solution. 分解残滓を溶解させた回収液中の金属量の測定が、原子吸光法または誘導結合プラズマ質量分析法による、請求項1〜4のいずれか一項に記載の多結晶シリコン中の金属不純物濃度測定方法。 The measurement of the amount of metal in the recovered liquid in which the decomposition residue is dissolved is performed by atomic absorption method or inductively coupled plasma mass spectrometry, and the measurement of the metal impurity concentration in the polycrystalline silicon according to any one of claims 1 to 4. Method. 測定される金属不純物が、Cu、Ni、Feから選ばれる少なくとも1種である、請求項1〜5のいずれか一項に記載の多結晶シリコン中の金属不純物濃度測定方法。 The method for measuring the concentration of metal impurities in polycrystalline silicon according to claim 1, wherein the metal impurities to be measured are at least one selected from Cu, Ni and Fe. 測定される金属不純物がCuである、請求6記載の多結晶シリコン中の金属不純物濃度測定方法。 The method for measuring a metal impurity concentration in polycrystalline silicon according to claim 6, wherein the metal impurity measured is Cu. FZ法による単結晶成長が、多結晶シリコンの高周波誘導加熱コイルとして銀製コイルを用いて行われてなる、請求項7記載の多結晶シリコン中の金属不純物濃度測定方法。 8. The method for measuring the concentration of metal impurities in polycrystalline silicon according to claim 7, wherein the single crystal growth by the FZ method is performed using a silver coil as a high frequency induction heating coil for polycrystalline silicon.
JP2016154011A 2016-08-04 2016-08-04 Method for measuring metal impurity concentration in polycrystalline silicon Active JP6732595B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2016154011A JP6732595B2 (en) 2016-08-04 2016-08-04 Method for measuring metal impurity concentration in polycrystalline silicon

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2016154011A JP6732595B2 (en) 2016-08-04 2016-08-04 Method for measuring metal impurity concentration in polycrystalline silicon

Publications (2)

Publication Number Publication Date
JP2018021852A JP2018021852A (en) 2018-02-08
JP6732595B2 true JP6732595B2 (en) 2020-07-29

Family

ID=61165627

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2016154011A Active JP6732595B2 (en) 2016-08-04 2016-08-04 Method for measuring metal impurity concentration in polycrystalline silicon

Country Status (1)

Country Link
JP (1) JP6732595B2 (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20220089341A1 (en) * 2019-01-25 2022-03-24 Tokuyama Corporation Polycrystalline Silicon Lump, Packaging Body Thereof, and Method for Producing Same
KR20220052915A (en) * 2019-08-23 2022-04-28 가부시키가이샤 도쿠야마 Polycrystalline silicon rod and manufacturing method thereof
CN113899600A (en) * 2020-06-19 2022-01-07 新疆新特新能材料检测中心有限公司 Preparation method and detection method of polycrystalline silicon surface metal detection sample
KR20220066147A (en) * 2020-07-21 2022-05-23 와커 헤미 아게 How to Measure Trace Metals in Silicon

Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4912528A (en) * 1988-07-01 1990-03-27 Hemlock Semiconductor Corporation Trace metals analysis in semiconductor material
US5436164A (en) * 1990-11-15 1995-07-25 Hemlock Semi-Conductor Corporation Analytical method for particulate silicon
JP2604924B2 (en) * 1991-07-23 1997-04-30 信越半導体株式会社 Method for analyzing impurities in silicon crystal
JPH0666695A (en) * 1992-08-20 1994-03-11 Matsushita Electron Corp Preparation of sample
JP3414976B2 (en) * 1997-03-07 2003-06-09 東芝セラミックス株式会社 Impurity analysis sample container and sample storage member used therein
JP3286215B2 (en) * 1997-07-17 2002-05-27 東芝セラミックス株式会社 Surface analysis method for silicon wafer
JPH11183342A (en) * 1997-12-25 1999-07-09 Toshiba Ceramics Co Ltd Sample processing method for high-accuracy impurity analysis of silicon material and processing unit used for it
JPH11304791A (en) * 1998-04-24 1999-11-05 Tokuyama Corp Method for analyzing impurity of polycrystal silicon
JP3473699B2 (en) * 2001-10-24 2003-12-08 三菱住友シリコン株式会社 Silicon wafer etching method and apparatus and impurity analysis method
JP2011153968A (en) * 2010-01-28 2011-08-11 Mitsubishi Materials Corp Decomposition apparatus for analysis of polycrystalline silicon
JP5459053B2 (en) * 2010-05-11 2014-04-02 信越半導体株式会社 Impurity evaluation method of silicon single crystal
WO2012114375A1 (en) * 2011-02-23 2012-08-30 信越半導体株式会社 Method for manufacturing n-type silicon single crystal, and phosphorus-doped n-type silicon single crystal

Also Published As

Publication number Publication date
JP2018021852A (en) 2018-02-08

Similar Documents

Publication Publication Date Title
JP6732595B2 (en) Method for measuring metal impurity concentration in polycrystalline silicon
US11440804B2 (en) Process for producing polycrystalline silicon mass
US5436164A (en) Analytical method for particulate silicon
JPH1095696A (en) Recovery of metal surface contaminant from silicon
TW201527731A (en) Method for determining a concentration of metal impurities contaminating a silicon product
JP2811582B2 (en) Analytical methods for trace metals in semiconductor materials.
US10077192B2 (en) Method for producing polycrystalline silicon
JPH11304791A (en) Method for analyzing impurity of polycrystal silicon
WO2021039569A1 (en) Polycrystalline silicon rod and method for manufacturing same
Grishechkin et al. Deep tellurium purification for the production of electronic and photonic materials
KR102208311B1 (en) Polycrystalline silicon cleaning method, manufacturing method and cleaning device
JPH0848512A (en) Polycrystalline silicon particle
JP2604924B2 (en) Method for analyzing impurities in silicon crystal
JP6459903B2 (en) Impurity analysis method and silicon single crystal manufacturing method
CN114599972B (en) Method for determining trace metals in silicon
JP6547614B2 (en) Method of analyzing metal impurities of silicon crystal and evaluation method
JPH0867511A (en) Production of polycrystal silicon
JP5413242B2 (en) Polycrystalline silicon impurity concentration measurement method
JP2000095534A (en) Purification of raw quartz powder
KR20190084300A (en) A method of decomposing quartz samples, a method of analyzing metal contamination of quartz samples, and a method of manufacturing quartz members
Pahlke Determination of Oxygen in Semiconductor Silicon by Gas Fusion Analysis GFA-Historical and Future Trends

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20190604

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20200313

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20200317

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20200609

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20200708

R150 Certificate of patent or registration of utility model

Ref document number: 6732595

Country of ref document: JP

Free format text: JAPANESE INTERMEDIATE CODE: R150