JP6642349B2 - Method for producing silicon single crystal, graphite sheet used therefor, and quartz crucible support container - Google Patents
Method for producing silicon single crystal, graphite sheet used therefor, and quartz crucible support container Download PDFInfo
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 title claims description 139
- 239000010453 quartz Substances 0.000 title claims description 137
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims description 96
- 229910002804 graphite Inorganic materials 0.000 title claims description 88
- 239000010439 graphite Substances 0.000 title claims description 88
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims description 76
- 229910052710 silicon Inorganic materials 0.000 title claims description 76
- 239000010703 silicon Substances 0.000 title claims description 76
- 239000013078 crystal Substances 0.000 title claims description 71
- 238000004519 manufacturing process Methods 0.000 title claims description 24
- 238000000034 method Methods 0.000 claims description 18
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 29
- 239000001301 oxygen Substances 0.000 description 29
- 229910052760 oxygen Inorganic materials 0.000 description 29
- 239000007789 gas Substances 0.000 description 10
- 229910052799 carbon Inorganic materials 0.000 description 8
- 230000001965 increasing effect Effects 0.000 description 8
- 230000007246 mechanism Effects 0.000 description 8
- 239000002131 composite material Substances 0.000 description 7
- NJPPVKZQTLUDBO-UHFFFAOYSA-N novaluron Chemical compound C1=C(Cl)C(OC(F)(F)C(OC(F)(F)F)F)=CC=C1NC(=O)NC(=O)C1=C(F)C=CC=C1F NJPPVKZQTLUDBO-UHFFFAOYSA-N 0.000 description 5
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- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- 238000010030 laminating Methods 0.000 description 2
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- 229920000049 Carbon (fiber) Polymers 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
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- 230000008859 change Effects 0.000 description 1
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- 230000002708 enhancing effect Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
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- 239000002994 raw material Substances 0.000 description 1
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Description
本発明は、チョクラルスキー法（以下、ＣＺ法という）によるシリコン単結晶の製造方法に関し、特に、シリコン融液を保持する石英ルツボとこの石英ルツボを収容する黒鉛ルツボとの間に設けられて両者の保護するための黒鉛シートを用いたシリコン単結晶の製造方法の改良に関する。また本発明は、そのようなシリコン単結晶の製造方法に用いる黒鉛シート並びに石英ルツボ支持容器に関する。 The present invention relates to a method for producing a silicon single crystal by the Czochralski method (hereinafter, referred to as CZ method), and in particular, is provided between a quartz crucible holding a silicon melt and a graphite crucible containing the quartz crucible. The present invention relates to an improvement in a method for manufacturing a silicon single crystal using a graphite sheet for protecting both. The present invention also relates to a graphite sheet and a quartz crucible support container used in such a method for producing a silicon single crystal.
半導体デバイスの基板材料となるシリコン単結晶の多くはＣＺ法により製造されている。ＣＺ法では石英ルツボ内に収容されたシリコン融液に種結晶を浸漬し、種結晶及び石英ルツボを回転させながら種結晶を徐々に上昇させることにより、種結晶の下端に単結晶を成長させる。ＣＺ法によれば大きな直径のシリコン単結晶インゴットを高い歩留りで製造することが可能である。 Many silicon single crystals used as substrate materials for semiconductor devices are manufactured by the CZ method. In the CZ method, a single crystal is grown at the lower end of the seed crystal by immersing a seed crystal in a silicon melt contained in a quartz crucible and gradually raising the seed crystal while rotating the seed crystal and the quartz crucible. According to the CZ method, a silicon single crystal ingot having a large diameter can be manufactured at a high yield.
ＣＺ法においてシリコン融液を支持するために使用されるルツボは、内側を石英ルツボとし、外側を支持ルツボとする二重構造であり、石英ルツボは支持ルツボに収容された状態で単結晶引き上げ装置内に設置されて使用される。例えば、特許文献１には、炭素繊維強化炭素複合素材（カーボンコンポジット）製の支持ルツボが記載されている。 The crucible used to support the silicon melt in the CZ method has a double structure in which the inner side is a quartz crucible and the outer side is a supporting crucible. The quartz crucible is housed in the supporting crucible and is a single crystal pulling apparatus. Installed and used inside. For example, Patent Document 1 describes a supporting crucible made of a carbon fiber reinforced carbon composite material (carbon composite).
石英ルツボはガラス製であり割れや欠けが生じやすいので、支持ルツボに収容する際の取扱いには十分な注意が必要である。また石英ルツボから発生するＳｉＯガス等がカーボン製の支持ルツボと反応して支持ルツボのＳｉＣ化や減肉等が発生するという問題もある。 Quartz crucibles are made of glass and are easily cracked or chipped. Therefore, sufficient care must be taken when handling them in a supporting crucible. Further, there is also a problem that SiO gas or the like generated from the quartz crucible reacts with the carbon supporting crucible to cause the supporting crucible to become SiC or to reduce the thickness.
このような問題に対処するため、石英ルツボと支持ルツボとの間に両者を保護するための部材として黒鉛シートを介在させることが行われている（例えば、特許文献１参照）。カーボンコンポジット製の成型体である支持ルツボは高価であるためその消耗をできるだけ抑えることが好ましいが、黒鉛シートを介在させた場合には石英ルツボとの反応による支持ルツボの消耗を抑えてその寿命を延ばすことができる。また、支持ルツボに石英ルツボを設置する際に石英ルツボに対する衝撃を緩衝することができ、また支持ルツボから石英ルツボを取り出しやすくすることもできる。 In order to cope with such a problem, a graphite sheet is interposed between the quartz crucible and the supporting crucible as a member for protecting the both (see, for example, Patent Document 1). Since the supporting crucible, which is a molded body made of carbon composite, is expensive, it is preferable to minimize its consumption.However, when a graphite sheet is interposed, the supporting crucible due to the reaction with the quartz crucible is suppressed and its life is shortened. Can be extended. In addition, when the quartz crucible is installed on the supporting crucible, the impact on the quartz crucible can be buffered, and the quartz crucible can be easily taken out from the supporting crucible.
黒鉛シートを採用した従来のシリコン単結晶の製造方法では、均一な厚さを有する１枚の黒鉛シートをカーボンコンポジット製の支持ルツボの内面全体に敷設した後に石英ルツボを収容し、石英ルツボと支持ルツボとの組み合わせからなる二重構造のルツボ（二重ルツボ）を用いてシリコン単結晶の引き上げ工程を行っていた。 In a conventional method of manufacturing a silicon single crystal using a graphite sheet, a single graphite sheet having a uniform thickness is laid on the entire inner surface of a supporting crucible made of carbon composite, and then the quartz crucible is housed and supported by the quartz crucible. The pulling process of the silicon single crystal has been performed using a double-structure crucible (double crucible) composed of a combination with a crucible.
しかしながら、従来のシリコン単結晶の製造方法では、結晶引き上げ条件を変えていないにもかかわらず、シリコン単結晶中の酸素濃度がバッチ間で大きくばらつくという問題がある。特に、結晶引き上げ工程の前半側においてその傾向が大きく、また何回も使用して消耗した支持ルツボを新品に交換したときの交換前後のバッチ間で酸素濃度のばらつきが大きくなる傾向が見られる。 However, in the conventional method for manufacturing a silicon single crystal, there is a problem that the oxygen concentration in the silicon single crystal greatly varies between batches even though the crystal pulling conditions are not changed. In particular, the tendency is large in the first half of the crystal pulling step, and the oxygen concentration tends to vary greatly between batches before and after the replacement when a used crucible used many times is replaced with a new one.
本発明は上記課題を解決するためになされたものであり、シリコン単結晶中の酸素濃度のバッチ間のばらつきを小さくすることが可能なシリコン単結晶の製造方法及びこれに用いる黒鉛シート並びに石英ルツボ支持容器を提供することにある。 The present invention has been made in order to solve the above-mentioned problems, and a method of manufacturing a silicon single crystal capable of reducing a variation in the oxygen concentration in a silicon single crystal between batches, a graphite sheet used therefor, and a quartz crucible. It is to provide a support container.
本願発明者らは、シリコン単結晶中の酸素濃度のバッチ間のばらつきが大きくなる原因について鋭意研究を重ねた結果、結晶引き上げ工程中の石英ルツボの底部の温度を低くすることで酸素濃度の安定化が図れることを見出した。 The present inventors have conducted intensive studies on the cause of the large variation in the oxygen concentration in the silicon single crystal between batches.As a result, the oxygen concentration can be stabilized by lowering the temperature at the bottom of the quartz crucible during the crystal pulling process. Was found to be possible.
本発明はこのような技術的知見に基づくものであり、本発明によるシリコン単結晶の製造方法は、支持ルツボ内に黒鉛シートを介して石英ルツボを収容すると共に、前記石英ルツボ内のシリコン融液からシリコン単結晶を引き上げるチョクラルスキー法によるシリコン単結晶の製造方法であって、前記黒鉛シートは、前記石英ルツボの直胴部と接する第１の領域と、前記石英ルツボの底部と接する第２の領域とを有し、前記第２の領域の熱伝導率は前記第１の領域の熱伝導率よりも低いことを特徴とする。 The present invention is based on such technical knowledge, and the method for producing a silicon single crystal according to the present invention includes a method in which a quartz crucible is accommodated in a supporting crucible via a graphite sheet and a silicon melt in the quartz crucible is contained. A method of manufacturing a silicon single crystal by the Czochralski method of pulling a silicon single crystal out of a quartz crucible, wherein the graphite sheet has a first region in contact with a straight body portion of the quartz crucible and a second region in contact with a bottom portion of the quartz crucible. Wherein the thermal conductivity of the second region is lower than the thermal conductivity of the first region.
また、本発明による黒鉛シートは、チョクラルスキー法によるシリコン単結晶の製造においてシリコン融液を支持する石英ルツボと前記石英ルツボを収容する支持ルツボとの間に設けられるものであって、前記石英ルツボの直胴部と接する第１の領域の熱伝導率が前記石英ルツボの底部と接する第２の領域の熱伝導率よりも低いことを特徴とする。 Further, the graphite sheet according to the present invention is provided between a quartz crucible supporting a silicon melt and a supporting crucible accommodating the quartz crucible in the production of a silicon single crystal by the Czochralski method, The thermal conductivity of the first region in contact with the straight body of the crucible is lower than the thermal conductivity of the second region in contact with the bottom of the quartz crucible.
さらに、本発明による石英ルツボ支持容器は、チョクラルスキー法によるシリコン単結晶の製造に用いられ、シリコン融液を支持する石英ルツボを収容する支持ルツボと、前記石英ルツボと前記支持ルツボとの間に設けられる黒鉛シートとを備え、前記黒鉛シートは、前記石英ルツボの直胴部と接する第１の領域と、前記石英ルツボの底部と接する第２の領域とを有し、前記第２の領域の熱伝導率は前記第１の領域の熱伝導率よりも低いことを特徴とする。 Further, the quartz crucible supporting container according to the present invention is used for producing a silicon single crystal by the Czochralski method, and a supporting crucible for accommodating a quartz crucible for supporting a silicon melt, and a space between the quartz crucible and the supporting crucible. The quartz sheet has a first region in contact with the straight body of the quartz crucible, and a second region in contact with the bottom of the quartz crucible, and the second region Has a lower thermal conductivity than that of the first region.
本発明によれば、黒鉛シートを用いて石英ルツボ及び支持ルツボを相互に保護することができる。特に、石英ルツボの外面のほぼ全面が黒鉛シートを介して支持ルツボの内面に接するので、黒鉛シートによって石英ルツボ全体を確実に保護することができる。また長時間の使用により消耗して支持ルツボの形状（肉厚）が変化したとしても、支持ルツボをすぐに交換することなく、黒鉛シートを介して石英ルツボ及び支持ルツボとの密着性を高めることができる。さらに、石英ルツボの直胴部と接する第２の領域の熱伝導率が石英ルツボの底部と接する第１の領域の熱伝導率よりも低いので、石英ルツボの底部の高温化を抑えることができ、これによりシリコン単結晶中の酸素濃度のバッチ間のばらつきを小さくすることができる。石英ルツボの底部の高温化を抑制することでシリコン単結晶中の酸素濃度のバッチ間のばらつきが低減される理由は明らかではないが、石英ルツボの底部が高温化するとシリコン融液の自然対流が活発化して外乱の影響を受けやすく、底部の高温化を抑制した場合にはそのような外乱の影響を抑えることができるからではないかと考えられる。 ADVANTAGE OF THE INVENTION According to this invention, a quartz crucible and a supporting crucible can be mutually protected using a graphite sheet. In particular, since almost the entire outer surface of the quartz crucible is in contact with the inner surface of the supporting crucible via the graphite sheet, the entire quartz crucible can be reliably protected by the graphite sheet. Also, even if the shape (thickness) of the supporting crucible changes due to wear due to prolonged use, the adhesion between the quartz crucible and the supporting crucible can be increased via the graphite sheet without immediately replacing the supporting crucible. Can be. Further, since the thermal conductivity of the second region in contact with the straight body of the quartz crucible is lower than the thermal conductivity of the first region in contact with the bottom of the quartz crucible, it is possible to suppress a rise in the temperature of the bottom of the quartz crucible. Thus, the variation in the oxygen concentration in the silicon single crystal between batches can be reduced. It is not clear why suppressing the temperature rise at the bottom of the quartz crucible reduces the batch-to-batch variation in the oxygen concentration in the silicon single crystal.However, when the temperature at the bottom of the quartz crucible rises, the natural convection of the silicon melt is reduced. It is supposed that the influence of the disturbance can be suppressed when the base is activated and easily affected by the disturbance, and when the temperature at the bottom is suppressed.
本発明において、前記黒鉛シートの前記第２の領域の厚さは、前記黒鉛シートの前記第１の領域の厚さよりも厚いことが好ましい。これによれば、黒鉛シートの第１及び第２の領域の熱伝導率を容易に異ならせることができる。 In the present invention, it is preferable that the thickness of the second region of the graphite sheet is larger than the thickness of the first region of the graphite sheet. According to this, the thermal conductivity of the first and second regions of the graphite sheet can be easily changed.
本発明において、前記黒鉛シートは、第１及び第２のシート部材を含み、前記第１のシート部材は、前記石英ルツボの直胴部を覆っており、前記第２のシート部材は、前記石英ルツボの底部を覆っていることが好ましい。このように、黒鉛シートを複数枚のシート部材で構成することで第１及び第２の領域の熱伝導率を容易に異ならせることができる。 In the present invention, the graphite sheet includes first and second sheet members, the first sheet member covers a straight body of the quartz crucible, and the second sheet member includes the quartz member. Preferably, it covers the bottom of the crucible. In this way, by configuring the graphite sheet with a plurality of sheet members, the thermal conductivity of the first and second regions can be easily changed.
本発明において、前記第１及び第２のシート部材は、所定の厚さを有するベースシートを１枚又は２枚以上重ねてなるものであり、前記第２のシート部材を構成する前記ベースシートの枚数は、前記第１のシート部材を構成する前記ベースシートの枚数よりも多いことが好ましい。これによれば、市販の均一な厚さの黒鉛シートを加工して第１及び第２のシート部材を簡単に作製することができる。 In the present invention, the first and second sheet members are formed by laminating one or two or more base sheets having a predetermined thickness. It is preferable that the number of sheets is larger than the number of the base sheets constituting the first sheet member. According to this, the first and second sheet members can be easily manufactured by processing a commercially available graphite sheet having a uniform thickness.
本発明において、前記黒鉛シートは、第１及び第２のシート部材を含み、前記第１のシート部材は、前記石英ルツボの直胴部と底部の両方と接しており、前記第２のシート部材は、前記第１のシート部材を介して前記石英ルツボの底部と接していることもまた好ましい。このように、第２のシート部材が石英ルツボと直接接しない構成であっても、黒鉛シートの第１及び第２の領域の熱伝導率を容易に異ならせることができる。 In the present invention, the graphite sheet includes first and second sheet members, wherein the first sheet member is in contact with both a straight body portion and a bottom portion of the quartz crucible, and the second sheet member Is also preferably in contact with the bottom of the quartz crucible via the first sheet member. As described above, even when the second sheet member does not directly contact the quartz crucible, the thermal conductivity of the first and second regions of the graphite sheet can be easily changed.
本発明によれば、シリコン単結晶中の酸素濃度のバッチ間のばらつきを小さくすることが可能なシリコン単結晶の製造方法及びこれに用いる黒鉛シート並びに石英ルツボ支持容器を提供することができる。 ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the silicon single crystal which can reduce the dispersion | variation between batches of the oxygen concentration in a silicon single crystal, a graphite sheet used for the same, and a quartz crucible support container can be provided.
以下、添付図面を参照しながら、本発明の好ましい実施の形態について詳細に説明する。 Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
図１は、本発明の実施の形態によるシリコン単結晶の製造方法を説明するための図であって、単結晶製造装置の構成を示す略側面断面図である。 FIG. 1 is a view for explaining a method of manufacturing a silicon single crystal according to an embodiment of the present invention, and is a schematic side sectional view showing a configuration of a single crystal manufacturing apparatus.
図１に示すように、単結晶製造装置１は、水冷式のチャンバー１０と、チャンバー１０内においてシリコン融液２を保持する石英ルツボ１１と、石英ルツボ１１を支持する支持ルツボ１２と、支持ルツボ１２を支持する回転シャフト１３と、回転シャフト１３を回転及び昇降駆動するシャフト駆動機構１４と、支持ルツボ１２の周囲に配置されたヒータ１５と、ヒータ１５の外側であってチャンバー１０の内面に沿って配置された断熱材１６と、シリコン融液２の上方に配置された熱遮蔽体１７と、石英ルツボ１１の上方であって回転シャフト１３と同軸上に配置された結晶引き上げワイヤー１８と、チャンバー１０の上方に配置されたワイヤー巻き取り機構１９とを備えている。 As shown in FIG. 1, the single crystal manufacturing apparatus 1 includes a water-cooled chamber 10, a quartz crucible 11 for holding the silicon melt 2 in the chamber 10, a support crucible 12 for supporting the quartz crucible 11, and a support crucible. A rotary shaft 13 for supporting the rotary shaft 12, a shaft drive mechanism 14 for rotating and raising and lowering the rotary shaft 13, a heater 15 disposed around the support crucible 12, and an outer surface of the heater 15 along the inner surface of the chamber 10. A heat insulating material 16 disposed above the silicon melt 2, a crystal pulling wire 18 disposed above the quartz crucible 11 and coaxial with the rotating shaft 13, and a chamber. And a wire take-up mechanism 19 disposed above the apparatus 10.
チャンバー１０は、メインチャンバー１０ａと、メインチャンバー１０ａの上部開口に連結された細長い円筒状のプルチャンバー１０ｂとで構成されており、石英ルツボ１１、支持ルツボ１２、ヒータ１５及び熱遮蔽体１７はメインチャンバー１０ａ内に設けられている。プルチャンバー１０ｂにはチャンバー１０内にアルゴンガス等の不活性ガス（パージガス）やドーパントガスを導入するためのガス導入口１０ｃが設けられており、メインチャンバー１０ａの下部にはチャンバー１０内の雰囲気ガスを排気するためのガス排気口１０ｄが設けられている。また、メインチャンバー１０ａの上部には覗き窓１０ｅが設けられており、シリコン単結晶３の育成状況を覗き窓１０ｅから観察可能である。 The chamber 10 includes a main chamber 10a and an elongated cylindrical pull chamber 10b connected to an upper opening of the main chamber 10a. The quartz crucible 11, the supporting crucible 12, the heater 15, and the heat shield 17 are It is provided in the chamber 10a. The pull chamber 10b is provided with a gas inlet 10c for introducing an inert gas (purge gas) such as argon gas or a dopant gas into the chamber 10, and an atmosphere gas in the chamber 10 is provided below the main chamber 10a. A gas exhaust port 10d for exhausting gas is provided. In addition, an observation window 10e is provided on the upper portion of the main chamber 10a, and the growth state of the silicon single crystal 3 can be observed from the observation window 10e.
石英ルツボ１１は、有底円筒状の石英ガラス製の容器である。支持ルツボ１２は、有底円筒状のカーボンコンポジット製の容器であり、加熱によって軟化した石英ルツボ１１の形状が維持されるように石英ルツボ１１の外表面に密着して石英ルツボ１１を支持する。石英ルツボ１１及び支持ルツボ１２はチャンバー１０内においてシリコン融液を支持する二重構造のルツボ２０を構成している。 The quartz crucible 11 is a bottomed cylindrical quartz glass container. The supporting crucible 12 is a bottomed cylindrical carbon composite container, and supports the quartz crucible 11 in close contact with the outer surface of the quartz crucible 11 so that the shape of the quartz crucible 11 softened by heating is maintained. The quartz crucible 11 and the supporting crucible 12 constitute a double-structure crucible 20 for supporting the silicon melt in the chamber 10.
石英ルツボ１１と支持ルツボ１２との間には黒鉛シート２１が設けられている。黒鉛シート２１は、石英ルツボ１１の割れや欠けを防止すると共に支持ルツボ１２の内面との密着性を高めるための緩衝材として機能する。また、黒鉛シート２１は、支持ルツボ１２の消耗を抑える保護シートとしても機能する。石英ルツボ１１が支持ルツボ１２の内面に直接接触していると、支持ルツボ１２が石英ルツボ１１と反応して徐々に減肉していき、支持ルツボ１２の寿命が短くなるが、両者の間に黒鉛シート２１を介在させている場合には支持ルツボ１２の代わりに黒鉛シート２１が石英ルツボ１１と反応するので、支持ルツボ１２の消耗を抑えてその寿命を延ばすことができる。 A graphite sheet 21 is provided between the quartz crucible 11 and the supporting crucible 12. The graphite sheet 21 functions as a cushioning material for preventing cracking and chipping of the quartz crucible 11 and enhancing adhesion to the inner surface of the supporting crucible 12. Further, the graphite sheet 21 also functions as a protection sheet for suppressing the consumption of the supporting crucible 12. When the quartz crucible 11 is in direct contact with the inner surface of the supporting crucible 12, the supporting crucible 12 reacts with the quartz crucible 11 and gradually decreases in wall thickness, and the life of the supporting crucible 12 is shortened. When the graphite sheet 21 is interposed, the graphite sheet 21 reacts with the quartz crucible 11 instead of the supporting crucible 12, so that consumption of the supporting crucible 12 can be suppressed and the life thereof can be extended.
このように、本実施形態においては黒鉛シート２１もルツボ２０の構成要素の一つである。また、黒鉛シート２１は支持ルツボ１２と共に石英ルツボ１１を支持する石英ルツボ支持容器２３を構成するものである。支持ルツボ１２が繰り返し使用されるのに対し、黒鉛シート２１は毎バッチごとに交換され、石英ルツボ１１と同様に新品が使用される。たとえ石英ルツボ１１との間に黒鉛シート２１を介在させたとしても、支持ルツボ１２は長時間の使用により消耗してその内面形状は徐々に変化するが、適切な厚さの黒鉛シート２１を介して石英ルツボ１１を収容することにより、石英ルツボ１１と支持ルツボ１２との黒鉛シート２１を介した密着性を高めることができる。 Thus, in the present embodiment, the graphite sheet 21 is also one of the components of the crucible 20. The graphite sheet 21 constitutes a quartz crucible support container 23 that supports the quartz crucible 11 together with the support crucible 12. While the supporting crucible 12 is used repeatedly, the graphite sheet 21 is replaced every batch, and a new article is used like the quartz crucible 11. Even if the graphite sheet 21 is interposed between the quartz crucible 11 and the supporting crucible 12, the inner shape of the supporting crucible gradually changes due to long-term use. By accommodating the quartz crucible 11, the adhesion between the quartz crucible 11 and the support crucible 12 via the graphite sheet 21 can be enhanced.
支持ルツボ１２は回転シャフト１３の上端部に固定されており、回転シャフト１３の下端部はチャンバー１０の底部を貫通してチャンバー１０の外側に設けられたシャフト駆動機構１４に接続されている。支持ルツボ１２、回転シャフト１３及びシャフト駆動機構１４は石英ルツボ１１の回転機構及び昇降機構を構成している。 The supporting crucible 12 is fixed to the upper end of the rotating shaft 13, and the lower end of the rotating shaft 13 passes through the bottom of the chamber 10 and is connected to a shaft driving mechanism 14 provided outside the chamber 10. The supporting crucible 12, the rotating shaft 13, and the shaft driving mechanism 14 constitute a rotating mechanism and a lifting mechanism of the quartz crucible 11.
ヒータ１５は、石英ルツボ１１内に充填されたシリコン原料を融解してシリコン融液２を生成すると共に、シリコン融液２を加熱してその溶融状態を維持するために用いられる。ヒータ１５は単一の部材で構成されていてもよく、独立に出力制御が可能な複数の部材の組み合わせであってもよい。ヒータ１５は例えば抵抗加熱式ヒータであり、支持ルツボ１２内の石英ルツボ１１を取り囲むように設けられている。さらにヒータ１５の外側には断熱材１６がヒータ１５を取り囲むように設けられており、これによりチャンバー１０内の保温性が高められている。 The heater 15 is used for melting the silicon raw material filled in the quartz crucible 11 to generate the silicon melt 2 and for heating the silicon melt 2 to maintain the molten state. The heater 15 may be composed of a single member, or may be a combination of a plurality of members whose output can be independently controlled. The heater 15 is, for example, a resistance heating type heater, and is provided so as to surround the quartz crucible 11 in the support crucible 12. Further, a heat insulating material 16 is provided outside the heater 15 so as to surround the heater 15, thereby increasing the heat retention in the chamber 10.
熱遮蔽体１７は、シリコン融液２の温度変動を抑制して結晶成長界面近傍に適切なホットゾーンを形成するとともに、ヒータ１５及び石英ルツボ１１からの輻射熱によるシリコン単結晶３の加熱を防止するために設けられている。熱遮蔽体１７は略円筒状の黒鉛製の部材であり、シリコン単結晶３の引き上げ経路を除いたシリコン融液２の上方の領域を覆うように設けられている。 The heat shield 17 suppresses the temperature fluctuation of the silicon melt 2 to form an appropriate hot zone near the crystal growth interface, and also prevents the silicon single crystal 3 from being heated by radiant heat from the heater 15 and the quartz crucible 11. It is provided for. The heat shield 17 is a substantially cylindrical member made of graphite, and is provided so as to cover a region above the silicon melt 2 excluding a pulling path of the silicon single crystal 3.
熱遮蔽体１７の下端部の開口１７ａの直径はシリコン単結晶３の直径よりも大きく、これによりシリコン単結晶３の引き上げ経路が確保されている。また熱遮蔽体１７の下端部の外径は石英ルツボ１１の口径よりも小さく、熱遮蔽体１７の下端部は石英ルツボ１１の内側に位置するので、石英ルツボ１１のリム上端を熱遮蔽体１７の下端よりも上方まで上昇させても熱遮蔽体１７が石英ルツボ１１と干渉することはない。 The diameter of the opening 17a at the lower end of the heat shield 17 is larger than the diameter of the silicon single crystal 3, thereby securing a pulling path of the silicon single crystal 3. The outer diameter of the lower end of the heat shield 17 is smaller than the diameter of the quartz crucible 11, and the lower end of the heat shield 17 is located inside the quartz crucible 11. The heat shield 17 does not interfere with the quartz crucible 11 even if it is raised above the lower end of the crucible.
図２は、石英ルツボ１１、支持ルツボ１２及び黒鉛シート２１の組み合わせからなるルツボ２０を分解して示す略側面断面図である。 FIG. 2 is a schematic side sectional view showing a crucible 20 composed of a combination of a quartz crucible 11, a support crucible 12, and a graphite sheet 21 in an exploded manner.
図２に示すように、シリコン融液２を支持するルツボ２０は、石英ルツボ１１と、石英ルツボ１１が収容される支持ルツボ１２と、石英ルツボ１１と支持ルツボ１２との間に設けられた黒鉛シート２１とで構成されている。 As shown in FIG. 2, the crucible 20 supporting the silicon melt 2 includes a quartz crucible 11, a support crucible 12 in which the quartz crucible 11 is housed, and graphite provided between the quartz crucible 11 and the support crucible 12. And a seat 21.
石英ルツボ１１は、シリコン融液２を支持するための石英ガラス製の容器であって、略円筒状の直胴部１１ａと、緩やかな湾曲形状を有する底部１１ｂと、直胴部１１ａと底部１１ｂとをつなぐコーナー部１１ｃとを有している。 The quartz crucible 11 is a vessel made of quartz glass for supporting the silicon melt 2 and has a substantially cylindrical straight body 11a, a bottom 11b having a gentle curve, a straight body 11a and a bottom 11b. And a corner portion 11c connecting the two.
支持ルツボ１２は、石英ルツボ１１を支持するためのカーボンコンポジット製の容器であって、石英ルツボ１１の直胴部１１ａを支持する直胴部１２ａと、石英ルツボ１１の底部１１ｂを支持する底部１２ｂと、石英ルツボ１１のコーナー部１１ｃを支持するコーナー部１２ｃとを有している。支持ルツボ１２の内面は石英ルツボ１１の外面とほぼ同一の立体形状を有している。支持ルツボ１２のコーナー部１１ｃは消耗が激しい部位であるため、他の部位よりも肉厚であることが好ましい。支持ルツボ１２の底部１２ｂは直胴部１２ａと同じ肉厚であってもよく、直胴部１２ａより厚くてもよい。 The supporting crucible 12 is a container made of carbon composite for supporting the quartz crucible 11, and includes a straight body 12a that supports the straight body 11a of the quartz crucible 11, and a bottom 12b that supports the bottom 11b of the quartz crucible 11. And a corner portion 12c that supports the corner portion 11c of the quartz crucible 11. The inner surface of the supporting crucible 12 has substantially the same three-dimensional shape as the outer surface of the quartz crucible 11. Since the corner portion 11c of the supporting crucible 12 is a portion that is greatly consumed, it is preferable that the corner portion 11c be thicker than other portions. The bottom portion 12b of the supporting crucible 12 may have the same thickness as the straight body portion 12a, or may be thicker than the straight body portion 12a.
本実施形態において、支持ルツボ１２の底部には円形の開口１２ｈが設けられており、この開口１２ｈが回転シャフト１３の台座１３ｂの凸部１３ａと組み合わされることにより、支持ルツボ１２を台座１３ｂ上の定位置に容易に設置することができ、回転シャフト１３の中心軸に対する正確な位置決めが可能となる。台座１３ｂは黒鉛性であり、カーボンコンポジットに比べて密度が高く、熱伝導率も高いことから、台座１３ｂの凸部１３ａを通じて石英ルツボ１１の底部１１ｂが特に高温化しやすい。しかし、本実施形態においては、支持ルツボ１２の底部１２ｂに敷かれる黒鉛シート２１の厚さを直胴部１２ａに敷かれる黒鉛シート２１の厚さよりも厚くしているので、石英ルツボ１１の底部１１ｂの高温化を抑えることができる。 In the present embodiment, a circular opening 12h is provided at the bottom of the supporting crucible 12, and the opening 12h is combined with the convex portion 13a of the pedestal 13b of the rotating shaft 13, so that the supporting crucible 12 is placed on the pedestal 13b. It can be easily installed at a fixed position, and accurate positioning with respect to the center axis of the rotating shaft 13 is possible. Since the pedestal 13b is graphitic, has a higher density and a higher thermal conductivity than the carbon composite, the bottom 11b of the quartz crucible 11 is particularly easily heated to a high temperature through the projection 13a of the pedestal 13b. However, in the present embodiment, the thickness of the graphite sheet 21 laid on the bottom 12b of the supporting crucible 12 is greater than the thickness of the graphite sheet 21 laid on the straight body 12a. Temperature can be suppressed.
本実施形態において、黒鉛シート２１は膨張黒鉛シートであり、支持ルツボ１２の直胴部１２ａの内面に敷設されて石英ルツボ１１の直胴部１１ａの外面を覆う第１のシート部材２１ａと、支持ルツボ１２の底部１２ｂからコーナー部１２ｃまでの内面に敷設されて石英ルツボ１１の底部１１ｂからコーナー部１１ｃまでの外面を覆う第２のシート部材２１ｂとの組み合わせからなる。すなわち、石英ルツボ１１の直胴部１１ａと接する黒鉛シート２１の第１の領域Ｓ１は第１のシート部材２１ａからなり、石英ルツボ１１の底部１１ｂと接する黒鉛シート２１の第２の領域Ｓ２は第２のシート部材２１ｂからなる。 In the present embodiment, the graphite sheet 21 is an expanded graphite sheet, a first sheet member 21 a laid on the inner surface of the straight body 12 a of the support crucible 12 and covering the outer surface of the straight body 11 a of the quartz crucible 11, It is a combination with a second sheet member 21b laid on the inner surface from the bottom 12b to the corner 12c of the crucible 12 and covering the outer surface from the bottom 11b to the corner 11c of the quartz crucible 11. That is, the first region S1 of the graphite sheet 21 that is in contact with the straight body 11a of the quartz crucible 11 is made of the first sheet member 21a, and the second region S2 of the graphite sheet 21 that is in contact with the bottom 11b of the quartz crucible 11 is the second region S2. And two sheet members 21b.
第１のシート部材２１ａは、支持ルツボ１２の直胴部１２ａの高さとほぼ同じ幅を有する１枚の帯状のシートを直胴部１２ａの内周面に沿って敷設したものである。第２のシート部材２１ｂは、支持ルツボ１２の底部１２ｂに仕込んだときに底部１２ｂ及びコーナー部１２ｃの湾曲形状とほぼ同一の立体形状となるように複数の切り込みが設けられたものである。したがって、第２のシート部材２１ｂに皺を発生させることなく支持ルツボ１２の底部１２ｂ及びコーナー部１２ｃのほぼ全面を覆うことができる。 The first sheet member 21a is formed by laying a band-shaped sheet having a width substantially equal to the height of the straight body portion 12a of the support crucible 12 along the inner peripheral surface of the straight body portion 12a. The second sheet member 21b is provided with a plurality of cuts so that when the second sheet member 21b is charged into the bottom portion 12b of the support crucible 12, it has the same three-dimensional shape as the curved shape of the bottom portion 12b and the corner portion 12c. Therefore, almost the entire bottom 12b and corner 12c of the supporting crucible 12 can be covered without wrinkling of the second sheet member 21b.
本実施形態において、第２のシート部材２１ｂの厚さＴ２は第１のシート部材２１ａの厚さＴ１よりも厚く、これにより第２のシート部材２１ｂの断熱性は第１のシート部材２１ａの断熱性よりも高くなっている。したがって、石英ルツボ１１の底部１１ｂの高温化を抑えることができる。 In the present embodiment, the thickness T2 of the second sheet member 21b is greater than the thickness T1 of the first sheet member 21a, so that the heat insulation of the second sheet member 21b is reduced by the heat insulation of the first sheet member 21a. Higher than sex. Therefore, it is possible to suppress a rise in the temperature of the bottom portion 11b of the quartz crucible 11.
図３（ａ）及び（ｂ）は、黒鉛シート２１の構成の一例を示す略断面図である。 3A and 3B are schematic cross-sectional views illustrating an example of the configuration of the graphite sheet 21. FIG.
図３（ａ）及び（ｂ）に示すように、黒鉛シート２１を構成する第１及び第２のシート部材２１ａ，２１ｂは共に１枚のベースシートを用いて構成されており、第２のシート部材２１ｂを構成するベースシート２２ｂ（第２のベースシート）の厚さＴ２は、第１のシート部材２１ａを構成するベースシート２２ａ（第１のベースシート）の厚さＴ１よりも厚い。 As shown in FIGS. 3A and 3B, the first and second sheet members 21a and 21b constituting the graphite sheet 21 are both formed using one base sheet, and the second sheet is formed. The thickness T2 of the base sheet 22b (second base sheet) forming the member 21b is greater than the thickness T1 of the base sheet 22a (first base sheet) forming the first sheet member 21a.
図４（ａ）及び（ｂ）は、黒鉛シート２１の構成の他の例を示す略断面図である。 4A and 4B are schematic cross-sectional views illustrating another example of the configuration of the graphite sheet 21. FIG.
図４（ａ）及び（ｂ）に示すように、黒鉛シート２１を構成する第１及び第２のシート部材２１ａ，２１ｂは、ベースシートを積層することによって互いの厚さが異なるように構成されたものである。具体的には、第１のシート部材２１ａは、厚さＴ１のベースシート２２ａを１枚だけ用いて構成されており、第２のシート部材２１ｂは、厚さＴ１のベースシート２２ａを３枚重ねて構成されている。 As shown in FIGS. 4A and 4B, the first and second sheet members 21a and 21b constituting the graphite sheet 21 are configured such that the thicknesses thereof are different from each other by laminating a base sheet. It is a thing. Specifically, the first sheet member 21a is configured using only one base sheet 22a having a thickness T1, and the second sheet member 21b is formed by stacking three base sheets 22a having a thickness T1. It is configured.
このように、第１及び第２のシート部材２１ａ，２１ｂは、１枚のシートの厚さを変えたものであってもよく、同じ厚さのシートを重ねることによって互いの厚さを変えるようにしたものであってもよい。 As described above, the first and second sheet members 21a and 21b may be formed by changing the thickness of one sheet. The first and second sheet members 21a and 21b change the thickness of each other by overlapping the sheets having the same thickness. It may be one that has been made.
支持ルツボ１２は高温下での繰り返しの使用によって徐々に消耗して減肉するため、断熱性も徐々に低下し、これにより石英ルツボ１１の底部１１ｂの高温化も徐々に進行する。石英ルツボ１１の底部１１ｂが高温化するとシリコン融液２の対流が活発化し、石英ルツボ１１から溶け出す酸素の量が増加してシリコン融液２中の酸素濃度が増加し、シリコン単結晶３に多くの酸素が取り込まれることでシリコン単結晶３中の酸素濃度が増加する。また、シリコン融液の対流が活発化すると外乱の影響を受けやすくなり、シリコン単結晶３中の酸素濃度のバッチ間のばらつきが生じやすくなる。特に、長時間の使用により減肉された支持ルツボ１２を新品に交換すると、交換前後のバッチ間でシリコン単結晶３中の酸素濃度のばらつきが大きくなる傾向がある。 Since the supporting crucible 12 is gradually consumed and reduced in thickness due to repeated use at a high temperature, the heat insulating property is also gradually reduced, whereby the temperature of the bottom 11b of the quartz crucible 11 is gradually increased. When the temperature of the bottom 11b of the quartz crucible 11 rises, the convection of the silicon melt 2 increases, the amount of oxygen dissolved from the quartz crucible 11 increases, and the oxygen concentration in the silicon melt 2 increases. By taking in a large amount of oxygen, the oxygen concentration in the silicon single crystal 3 increases. In addition, when the convection of the silicon melt is activated, it is easily affected by disturbance, and the oxygen concentration in the silicon single crystal 3 tends to vary from batch to batch. In particular, when the support crucible 12 whose wall thickness has been reduced by using for a long time is replaced with a new one, the variation in the oxygen concentration in the silicon single crystal 3 between the batches before and after the replacement tends to increase.
しかし、本実施形態においては黒鉛シート２１を高さ方向に２分割し、石英ルツボ１１の底部１１ｂを覆うように底部１１ｂと接する黒鉛シート２１の下部領域（第２の領域）Ｓ２の厚さを、石英ルツボ１１の直胴部１１ａを覆うように直胴部１１ａと接する黒鉛シート２１の上部領域（第１の領域）Ｓ１の厚さよりも厚くしているので、石英ルツボ１１の底部１１ｂの高温化を抑えることができ、シリコン単結晶３中の酸素濃度のバッチ間のばらつきを抑えることができる。 However, in the present embodiment, the graphite sheet 21 is divided into two in the height direction, and the thickness of the lower region (second region) S2 of the graphite sheet 21 that is in contact with the bottom 11b so as to cover the bottom 11b of the quartz crucible 11 is reduced. Since the thickness of the upper region (first region) S1 of the graphite sheet 21 which is in contact with the straight body portion 11a so as to cover the straight body portion 11a of the quartz crucible 11, the bottom portion 11b of the quartz crucible 11 has a high temperature. And the variation in the oxygen concentration in the silicon single crystal 3 between batches can be suppressed.
図５（ａ）及び（ｂ）は、黒鉛シート２１の構成のさらに他の例を示す略断面図である。 FIGS. 5A and 5B are schematic sectional views showing still another example of the configuration of the graphite sheet 21. FIG.
図５（ａ）及び（ｂ）に示すように、この黒鉛シート２１は、第１のシート部材２１ａが石英ルツボ１１の底部１１ｂから直胴部１１ａまでのほぼ全面を覆うように成形及び配置されており、第２のシート部材２１ｂが石英ルツボ１１の底部１１ｂ及びコーナー部１１ｃの少なくとも一部を覆うように成形及び配置されたものである。特に、図５（ａ）に示す黒鉛シート２１では、第２のシート部材２１ｂが第１のシート部材２１ａの内側に位置しており、図５（ｂ）に示す黒鉛シート２１では、第２のシート部材２１ｂが第１のシート部材２１ａの外側に位置している。そのため、図５（ｂ）に示す黒鉛シート２１では、第１のシート部材２１ａが石英ルツボ１１の直胴部１１ａと底部１１ｂの両方と接しており、第２のシート部材２１ｂが第１のシート部材２１ａを介して石英ルツボ１１の底部１１ｂと接している。 As shown in FIGS. 5A and 5B, the graphite sheet 21 is formed and arranged so that the first sheet member 21a covers almost the entire surface from the bottom 11b of the quartz crucible 11 to the straight body 11a. The second sheet member 21b is formed and arranged so as to cover at least a part of the bottom 11b and the corner 11c of the quartz crucible 11. In particular, in the graphite sheet 21 shown in FIG. 5A, the second sheet member 21b is located inside the first sheet member 21a, and in the graphite sheet 21 shown in FIG. The sheet member 21b is located outside the first sheet member 21a. Therefore, in the graphite sheet 21 shown in FIG. 5B, the first sheet member 21a is in contact with both the straight body portion 11a and the bottom portion 11b of the quartz crucible 11, and the second sheet member 21b is the first sheet member. It is in contact with the bottom 11b of the quartz crucible 11 via the member 21a.
このように、本実施形態による黒鉛シート２１は、第１及び第２のシート部材２１ａ，２１ｂの組み合わせにより、石英ルツボ１１の底部１１ｂと接する黒鉛シート２１の下部領域（第２の領域Ｓ２）の厚さを、石英ルツボ１１の直胴部１１ａと接する黒鉛シート２１の上部領域（第１の領域Ｓ１）の厚さよりも厚くしているので、石英ルツボ１１の底部１１ｂの高温化を抑えることができ、シリコン単結晶３中の酸素濃度のバッチ間のばらつきを抑えることができる。 As described above, the graphite sheet 21 according to the present embodiment has a lower area (second area S2) of the graphite sheet 21 that is in contact with the bottom 11b of the quartz crucible 11 due to the combination of the first and second sheet members 21a and 21b. Since the thickness is larger than the thickness of the upper region (first region S1) of the graphite sheet 21 which is in contact with the straight body portion 11a of the quartz crucible 11, it is possible to suppress the temperature rise of the bottom portion 11b of the quartz crucible 11. As a result, the variation in the oxygen concentration in the silicon single crystal 3 between batches can be suppressed.
以上、本発明の好ましい実施形態について説明したが、本発明は、上記の実施形態に限定されることなく、本発明の主旨を逸脱しない範囲で種々の変更が可能であり、それらも本発明の範囲内に包含されるものであることはいうまでもない。 As described above, the preferred embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention. It goes without saying that they are included in the range.
例えば、上記実施形態においては、黒鉛シート２１を高さ方向に２分割し、第１のシート部材２１ａと第２のシート部材２１ｂとの組み合わせからなる場合を例に挙げたが、本発明はこのような場合に限定されず、例えば黒鉛シート２１を高さ方向に３分割したものであってもよく、分割数や分割方法は特に限定されない。また本発明においては黒鉛シート２１を高さ方向に分割することなく単一のシートで構成し、石英ルツボ１１の底部１１ｂを覆う下部領域（第２の領域）の厚さが直胴部１１ａを覆う上部領域（第１の領域）の厚さよりも厚くなるように構成することも可能である。 For example, in the above-described embodiment, the case where the graphite sheet 21 is divided into two in the height direction and a combination of the first sheet member 21a and the second sheet member 21b is taken as an example, but the present invention is not limited to this. The invention is not limited to such a case. For example, the graphite sheet 21 may be divided into three in the height direction, and the number of divisions and the division method are not particularly limited. In the present invention, the graphite sheet 21 is formed of a single sheet without being divided in the height direction, and the thickness of the lower region (second region) covering the bottom portion 11b of the quartz crucible 11 is the same as that of the straight body portion 11a. It is also possible to configure so as to be thicker than the thickness of the upper region (first region) to be covered.
黒鉛シート２１の第１及び第２のシート部材２１ａ，２１ｂの厚さが石英ルツボ１１の底部中心の温度に与える影響を考察するため伝熱解析を行った。黒鉛シート２１のサンプルを表１に示す。 A heat transfer analysis was performed to consider the effect of the thickness of the first and second sheet members 21 a and 21 b of the graphite sheet 21 on the temperature at the center of the bottom of the quartz crucible 11. Table 1 shows a sample of the graphite sheet 21.
サンプル１（Ｎｏ．１）では、支持ルツボ１２の底部１２ｂからコーナー部１２ｃまでの領域に１枚のベースシートからなる第２のシート部材２１ｂを敷設し、支持ルツボ１２の直胴部１２ａに１枚のベースシートからなる第１のシート部材２１ａを敷設した。第１のシート部材のベースシートと第２のシート部材のベースシートは、材質と厚み（０．５ｍｍ）が同じであり、平面形状だけが異なる。
In sample 1 (No. 1), a second sheet member 21 b made of one base sheet is laid in the region from the bottom 12 b to the corner 12 c of the supporting crucible 12, A first sheet member 21a composed of two base sheets was laid. The base sheet of the first sheet member and the base sheet of the second sheet member have the same material and thickness (0.5 mm), and differ only in the planar shape.
サンプル２（Ｎｏ．２）では第１及び第２のシート部材２１ａ、２１ｂを構成するベースシートの枚数をそれぞれ１枚及び２枚とし、サンプル３（Ｎｏ．３）では１枚及び３枚とし、サンプル４（Ｎｏ．４）では２枚ずつとした。ベースシートの厚さは、０．５ｍｍとした。このような黒鉛シート２１を介して支持ルツボ１２内に収容された石英ルツボ１１の底部中心の温度を計算により求めた。 In Sample 2 (No. 2), the number of base sheets constituting the first and second sheet members 21a and 21b was 1 and 2, respectively. In Sample 3 (No. 3), 1 and 3 sheets. In sample 4 (No. 4), two sheets were used. The thickness of the base sheet was 0.5 mm. The temperature at the center of the bottom of the quartz crucible 11 housed in the supporting crucible 12 via the graphite sheet 21 was obtained by calculation.
図６は、黒鉛シートのサンプル１〜４の伝熱解析結果を示す棒グラフであって、縦軸はサンプル１（Ｎｏ．１）の温度を基準（１００）としたときの石英ルツボ１１の底部中心の温度の相対値（温度比率）を示している。 FIG. 6 is a bar graph showing the results of heat transfer analysis of samples 1 to 4 of the graphite sheet, where the vertical axis represents the center of the bottom of quartz crucible 11 when the temperature of sample 1 (No. 1) is set as a reference (100). Shows the relative value (temperature ratio) of the temperature.
図６から明らかなように、サンプル２（Ｎｏ．２）では第２のシート部材２１ｂを構成するベースシートの枚数を２枚に増やしたことにより底部中心の温度がサンプル１（Ｎｏ．１）よりも低下し、サンプル３（Ｎｏ．３）ではベースシートの枚数をさらに３枚に増やしたことにより底部中心の温度がサンプル２（Ｎｏ．２）よりもさらに低下した。サンプル４（Ｎｏ．４）では、サンプル１（Ｎｏ．１）よりも底部中心の温度が低下したが、サンプル２よりも高くなった。これは、第２のシート部材２１ｂのみならず第１のシート部材２１ａを構成するベースシートの枚数も２枚としたことで、直胴部の熱伝導率が低下し、直胴部側での熱不足を補うためヒータ１５のパワーを大きくしたことが原因である。 As is clear from FIG. 6, in sample 2 (No. 2), the number of base sheets constituting the second sheet member 21b is increased to two, so that the temperature at the bottom center is lower than that in sample 1 (No. 1). In the sample 3 (No. 3), the number of base sheets was further increased to three sheets, so that the temperature at the bottom center was further lowered than that in the sample 2 (No. 2). In sample 4 (No. 4), the temperature at the bottom center was lower than that in sample 1 (No. 1), but higher than in sample 2. This is because the number of base sheets constituting not only the second sheet member 21b but also the first sheet member 21a is set to two, so that the thermal conductivity of the straight body part is reduced and the straight body part side has This is because the power of the heater 15 is increased to compensate for the heat shortage.
次に、シリコン単結晶３中の酸素濃度のバッチ間のばらつきについて考察するため、黒鉛シート２１の条件が異なる点以外は同一の引き上げ条件下で製造された７本分のシリコン単結晶を用意した。黒鉛シート２１の条件としては上記サンプル１〜３（Ｎｏ．１〜３）を採用した。 Next, in order to consider the variation of the oxygen concentration in the silicon single crystal 3 between batches, seven silicon single crystals manufactured under the same pulling conditions except that the conditions of the graphite sheet 21 were different were prepared. . Samples 1 to 3 (Nos. 1 to 3) were used as conditions for the graphite sheet 21.
次に、サンプル１〜３の各々において７本のシリコン単結晶の酸素濃度を測定し、その標準偏差を算出した。シリコン単結晶中の酸素濃度は、結晶トップ側で高く、結晶ボトム側に向かって徐々に低くなる傾向があるため、複数本のシリコン単結晶インゴット間の酸素濃度を比較する場合には、結晶成長方向における酸素濃度の測定位置をバッチ間で揃える必要がある。この評価試験では、結晶トップから５００ｍｍの位置で酸素濃度の測定を行った。なお酸素濃度は、ＡＳＴＭ Ｆ−１２１（１９７９）に規格されたフーリエ変換赤外分光光度法（ＦＴ−ＩＲ）による測定値である。 Next, in each of Samples 1 to 3, the oxygen concentration of seven silicon single crystals was measured, and the standard deviation was calculated. Since the oxygen concentration in a silicon single crystal tends to be higher at the top of the crystal and gradually lower toward the bottom of the crystal, when comparing the oxygen concentration between a plurality of silicon single crystal ingots, the crystal growth The measurement position of the oxygen concentration in the direction needs to be aligned between batches. In this evaluation test, the oxygen concentration was measured at a position 500 mm from the crystal top. The oxygen concentration is a value measured by Fourier transform infrared spectrophotometry (FT-IR) standardized by ASTM F-121 (1979).
図７は、黒鉛シートのサンプル１〜３を使用した場合におけるシリコン単結晶中の酸素濃度Ｏｉの標準偏差を示す棒グラフである。 FIG. 7 is a bar graph showing the standard deviation of the oxygen concentration Oi in the silicon single crystal when the graphite sheet samples 1 to 3 are used.
図７から明らかなように、サンプル１（Ｎｏ．１）では酸素濃度Ｏｉの標準偏差が約０．５８×１０１７（ａｔｏｍｓ／ｃｍ３）であるのに対し、サンプル２（Ｎｏ．２）では約０．２９×１０１７（ａｔｏｍｓ／ｃｍ３）となり、サンプル３（Ｎｏ．３）では約０．２７×１０１７（ａｔｏｍｓ／ｃｍ３）となり、石英ルツボ１１の底部中心の温度の低下に合わせて酸素濃度Ｏｉの標準偏差も低下する結果となった。 As is clear from FIG. 7, the standard deviation of the oxygen concentration Oi is about 0.58 × 10 17 (atoms / cm 3 ) in the sample 1 (No. 1), whereas in the sample 2 (No. 2). It was about 0.29 × 10 17 (atoms / cm 3 ), and about 0.27 × 10 17 (atoms / cm 3 ) for Sample 3 (No. 3), which was adjusted to the lowering of the temperature at the bottom center of the quartz crucible 11. As a result, the standard deviation of the oxygen concentration Oi also decreased.
以上の結果から、石英ルツボ１１の底部１１ｂをカバーする黒鉛シート２１の第２のシート部材２１ｂの厚さが直胴部１１ａをカバーする第１のシート部材２１ａの厚さよりも厚い場合には、シリコン単結晶中の酸素濃度のバッチ間のばらつきを低減できることが分かった。また第２のシート部材２１ｂのベースシート枚数を１枚から２枚に増やした場合には酸素濃度のバッチ間のばらつきの抑制効果が非常に大きいが、２枚から３枚に増やしても２枚に増やした場合ほど大きな効果は見られなかった。 From the above results, when the thickness of the second sheet member 21b of the graphite sheet 21 covering the bottom 11b of the quartz crucible 11 is larger than the thickness of the first sheet member 21a covering the straight body 11a, It has been found that the batch-to-batch variation of the oxygen concentration in the silicon single crystal can be reduced. Further, when the number of base sheets of the second sheet member 21b is increased from one to two, the effect of suppressing the variation in the oxygen concentration between batches is very large. The effect was not so great as when the number was increased.
１ 単結晶製造装置
２ シリコン融液
３ シリコン単結晶
１０ チャンバー
１０ａ メインチャンバー
１０ｂ プルチャンバー
１０ｃ ガス導入口
１０ｄ ガス排気口
１０ｅ 覗き窓
１１ 石英ルツボ
１１ａ 石英ルツボの直胴部
１１ｂ 石英ルツボの底部
１１ｃ 石英ルツボのコーナー部
１２ 支持ルツボ
１２ａ 支持ルツボの直胴部
１２ｂ 支持ルツボの底部
１２ｃ 支持ルツボのコーナー部
１２ｈ 支持ルツボの開口
１３ 回転シャフト
１３ａ 回転シャフトの凸部
１３ｂ 回転シャフトの台座
１４ シャフト駆動機構
１５ ヒータ
１６ 断熱材
１７ 熱遮蔽体
１７ａ 熱遮蔽体の開口
１８ 引き上げワイヤー
１９ ワイヤー巻き取り機構
２１ 黒鉛シート
２１ａ 第１のシート部材
２１ｂ 第２のシート部材
２２ａ ベースシート
２２ｂ ベースシート
２３ 石英ルツボ支持容器
DESCRIPTION OF SYMBOLS 1 Single crystal manufacturing apparatus 2 Silicon melt 3 Silicon single crystal 10 Chamber 10a Main chamber 10b Pull chamber 10c Gas inlet 10d Gas exhaust port 10e Viewing window 11 Quartz crucible 11a Straight crucible body 11b Quartz crucible bottom 11c Quartz crucible Corner portion 12 of supporting crucible 12a Straight body portion of supporting crucible 12b Bottom portion of supporting crucible 12c Corner portion of supporting crucible 12h Opening of supporting crucible 13 Rotating shaft 13a Convex portion 13b of rotating shaft Pedestal of rotating shaft 14 Shaft driving mechanism 15 Heater 16 Heat insulating material 17 Heat shield 17a Opening of heat shield 18 Pull-up wire 19 Wire winding mechanism 21 Graphite sheet 21a First sheet member 21b Second sheet member 22a Base sheet 22b Base sheet 23 Quartz crucible support container
Claims (7)
前記石英ルツボは、略円筒状の直胴部と、湾曲した底部と、直胴部と底部とをつなぐコーナー部とを有し、
前記黒鉛シートは、前記石英ルツボの直胴部とその周方向の全域で接する第１の領域と、前記石英ルツボの底部と接する第２の領域とを有し、前記第２の領域の熱伝導率は前記第１の領域の熱伝導率よりも低いことを特徴とするシリコン単結晶の製造方法。 A method for producing a silicon single crystal by a Czochralski method of accommodating a quartz crucible in a supporting crucible via a graphite sheet and pulling up a silicon single crystal from a silicon melt in the quartz crucible,
The quartz crucible has a substantially cylindrical straight body, a curved bottom, and a corner connecting the straight body and the bottom,
The graphite sheet has a first region in contact with the straight body portion of the quartz crucible in the entire circumferential area thereof, and a second region in contact with the bottom portion of the quartz crucible. A method for producing a silicon single crystal, wherein the rate is lower than the thermal conductivity of the first region.
前記第１のシート部材は、前記石英ルツボの直胴部と接し、
前記第２のシート部材は、前記石英ルツボの底部と接している、請求項１又は２に記載のシリコン単結晶の製造方法。 The graphite sheet includes first and second sheet members,
The first sheet member is in contact with a straight body of the quartz crucible,
The method for producing a silicon single crystal according to claim 1, wherein the second sheet member is in contact with a bottom of the quartz crucible.
前記第２のシート部材を構成する前記ベースシートの枚数は、前記第１のシート部材を構成する前記ベースシートの枚数よりも多い、請求項３に記載のシリコン単結晶の製造方法。 The first and second sheet members are formed by stacking one or two or more base sheets having a predetermined thickness,
The method of manufacturing a silicon single crystal according to claim 3, wherein the number of the base sheets constituting the second sheet member is larger than the number of the base sheets constituting the first sheet member.
前記第１のシート部材は、前記石英ルツボの直胴部と底部の両方と接しており、
前記第２のシート部材は、前記第１のシート部材を介して前記石英ルツボの底部と接している、請求項１又は２に記載のシリコン単結晶の製造方法。 The graphite sheet includes first and second sheet members,
The first sheet member is in contact with both the straight body and the bottom of the quartz crucible,
The method for producing a silicon single crystal according to claim 1, wherein the second sheet member is in contact with a bottom of the quartz crucible via the first sheet member.
前記石英ルツボは、略円筒状の直胴部と、湾曲した底部と、直胴部と底部とをつなぐコーナー部とを有し、
前記黒鉛シートは、前記石英ルツボの直胴部とその周方向の全域で接する第１の領域と、前記石英ルツボの底部と接する第２の領域とを有し、
前記第２の領域の熱伝導率は前記第１の領域の熱伝導率よりも低いことを特徴とする黒鉛シート。 A graphite sheet provided between a quartz crucible supporting a silicon melt and a supporting crucible containing the quartz crucible in the production of a silicon single crystal by the Czochralski method,
The quartz crucible has a substantially cylindrical straight body, a curved bottom, and a corner connecting the straight body and the bottom,
The graphite sheet has a first region in contact with a straight body portion of the quartz crucible and an entire region in a circumferential direction thereof, and a second region in contact with a bottom portion of the quartz crucible,
The graphite sheet, wherein a thermal conductivity of the second region is lower than a thermal conductivity of the first region .
前記石英ルツボと前記支持ルツボとの間に設けられる黒鉛シートとを備え、
前記支持ルツボは、前記石英ルツボの略円筒状の直胴部を支持する直胴部と、前記石英ルツボの湾曲した底部を支持する底部と、前記石英ルツボの直胴部と底部とをつなぐコーナー部を支持するコーナー部とを有し、
前記黒鉛シートは、前記石英ルツボの直胴部とその周方向の全域で接する第１の領域と、前記石英ルツボの底部と接する第２の領域とを有し、前記第２の領域の熱伝導率は前記第１の領域の熱伝導率よりも低いことを特徴とする石英ルツボ支持容器。 A supporting crucible that is used for producing a silicon single crystal by the Czochralski method and contains a quartz crucible that supports a silicon melt,
A graphite sheet provided between the quartz crucible and the supporting crucible,
The supporting crucible includes a straight body that supports a substantially cylindrical straight body of the quartz crucible, a bottom that supports a curved bottom of the quartz crucible, and a corner that connects the straight body and the bottom of the quartz crucible. And a corner part supporting the part,
The graphite sheet has a first region in contact with the straight body portion of the quartz crucible in the entire circumferential area thereof, and a second region in contact with the bottom portion of the quartz crucible. The quartz crucible supporting container, wherein a rate is lower than a thermal conductivity of the first region.
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