JP4367213B2 - Method for producing silicon single crystal - Google Patents

Method for producing silicon single crystal Download PDF

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JP4367213B2
JP4367213B2 JP2004124979A JP2004124979A JP4367213B2 JP 4367213 B2 JP4367213 B2 JP 4367213B2 JP 2004124979 A JP2004124979 A JP 2004124979A JP 2004124979 A JP2004124979 A JP 2004124979A JP 4367213 B2 JP4367213 B2 JP 4367213B2
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義博 児玉
修二 大森
淳 岩崎
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Shin Etsu Handotai Co Ltd
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本発明は、FZ法によるシリコン単結晶の製造方法に関するものであり、より詳しくはFZ法による高抵抗率でかつ大口径のP型またはN型のシリコン単結晶を低コストで製造する方法に関する。   The present invention relates to a method for producing a silicon single crystal by the FZ method, and more particularly to a method for producing a high resistivity P-type or N-type silicon single crystal by the FZ method at a low cost.

従来、高耐圧パワーデバイスやサイリスタ等のパワーデバイス作製用にはフローティングゾーン法(FZ法)により製造された高抵抗率のシリコンウェーハが使用されてきた。また近年、半導体デバイスの性能向上とコストの低減のため、大口径のシリコンウェーハが求められ、これに伴って大口径シリコン単結晶の育成が要求されている。   Conventionally, high resistivity silicon wafers manufactured by a floating zone method (FZ method) have been used for manufacturing power devices such as high voltage power devices and thyristors. In recent years, in order to improve the performance of semiconductor devices and reduce costs, a large-diameter silicon wafer has been demanded, and accordingly, growth of a large-diameter silicon single crystal has been demanded.

さらに、特に近年、移動体通信用の半導体デバイスや、最先端のC−MOSデバイスでは、寄生容量の低減が必要とされている。信号の伝送ロスやショットキーバリヤダイオードにおける寄生容量は、高抵抗率の基板を用いることによって効果的に低減できることが報告されている。   Further, in particular, in recent years, semiconductor devices for mobile communication and state-of-the-art C-MOS devices have been required to reduce parasitic capacitance. It has been reported that signal transmission loss and parasitic capacitance in a Schottky barrier diode can be effectively reduced by using a high resistivity substrate.

また、前記半導体デバイスを更に高性能にするために、いわゆるSOI(Silicon On Insulator)ウェーハが用いられることもある。このSOIウェーハの代表的な製造方法として、ウェーハの貼り合わせ法がある。この方法は、デバイス形成層となるボンドウェーハと支持基板となるベースウェーハとを酸化膜を介して密着させ、熱処理を加えて両者を強固に結合し、その後ボンドウェーハを薄膜化してSOI層として、貼り合わせSOIウェーハを製造するというものである。   In order to further improve the performance of the semiconductor device, a so-called SOI (Silicon On Insulator) wafer may be used. As a typical manufacturing method of this SOI wafer, there is a wafer bonding method. In this method, a bond wafer to be a device forming layer and a base wafer to be a support substrate are brought into close contact with each other through an oxide film, heat treatment is performed to firmly bond both, and then the bond wafer is thinned to form an SOI layer. A bonded SOI wafer is manufactured.

このような方法で製造された貼り合わせSOIウェーハを用いて半導体デバイスを製造する場合においても、前述したウェーハの大口径化が要求され、また信号の伝送ロス等の問題を解決するために高抵抗率のウェーハをベースウェーハとして用いることが望まれていた。   Even in the case of manufacturing a semiconductor device using a bonded SOI wafer manufactured by such a method, it is required to increase the diameter of the wafer as described above, and a high resistance to solve problems such as signal transmission loss. It has been desired to use a high rate wafer as a base wafer.

そして、このような大口径化の要求が強い半導体デバイスに用いられるウェーハには、FZ法に代わり結晶の大型化に有利な、チョクラルスキー法(CZ法)によって製造されたシリコン単結晶が使われるようになってきた。CZ法によるシリコン単結晶の製造方法は、一般に良く知られているように、単結晶製造装置に配置された石英ルツボ内で多結晶シリコン原料を溶融させたシリコン融液に種結晶を浸漬し、石英ルツボと種結晶を反対方向に回転させながら融液に浸漬した種結晶を上方に静かに引上げることにより、略円柱状のシリコン単結晶を育成するというものである。   For a wafer used in such a semiconductor device which is required to have a large diameter, a silicon single crystal manufactured by the Czochralski method (CZ method), which is advantageous for increasing the size of the crystal instead of the FZ method, is used. It has come to be. As is generally well known, a method for producing a silicon single crystal by the CZ method involves immersing a seed crystal in a silicon melt obtained by melting a polycrystalline silicon raw material in a quartz crucible disposed in a single crystal production apparatus, The seed crystal immersed in the melt is gently pulled upward while rotating the quartz crucible and the seed crystal in the opposite direction, thereby growing a substantially cylindrical silicon single crystal.

このようなCZ法によるシリコン単結晶の製造方法ではシリコン融液の保持に石英ルツボを使用しているため、高温のシリコン融液とルツボ内壁の石英が反応して、シリコン融液中に酸素原子が溶け出し、この酸素が融液を通して育成中の単結晶に取り込まれる。   In such a method for producing a silicon single crystal by the CZ method, a quartz crucible is used to hold a silicon melt, so that a high-temperature silicon melt reacts with quartz on the inner wall of the crucible, and oxygen atoms are contained in the silicon melt. Dissolves and this oxygen is taken into the growing single crystal through the melt.

単結晶中に取り込まれた酸素原子は通常単独では電気的に中性であるが、単結晶に350〜500℃の低温熱処理が施されると複数個の酸素原子が集まって電子を放出して電気的に活性な酸素ドナーとなる。そのため、CZ法により得られた高抵抗率のウェーハに、デバイス製造工程、例えば酸化膜形成、不純物拡散、配線工程等で350〜500℃程度の熱処理が施されると、この酸素ドナーの形成により高抵抗率CZウェーハの抵抗率が低下してしまうという問題がある。   Oxygen atoms taken into a single crystal are normally electrically neutral by themselves, but when a single crystal is subjected to a low temperature heat treatment at 350 to 500 ° C., a plurality of oxygen atoms gather and emit electrons. It becomes an electrically active oxygen donor. Therefore, when a high-resistivity wafer obtained by the CZ method is subjected to a heat treatment of about 350 to 500 ° C. in a device manufacturing process, for example, oxide film formation, impurity diffusion, wiring process, etc., this oxygen donor is formed. There exists a problem that the resistivity of a high resistivity CZ wafer will fall.

このような酸素ドナーの形成による抵抗率の低下を防ぎ、CZ法を用いて高抵抗率のシリコンウェーハを得る方法の一つとして、結晶育成時に格子間酸素濃度が低くなるようにシリコン単結晶を製造する方法が開示されている。例えば、合成石英ルツボを用いてMCZ法(CZ法においてシリコン融液に磁場を印加する方法)で単結晶の育成を行うことにより、単結晶に溶け込む酸素量を制御して、10000Ω・cm以上の高抵抗率を有するシリコン単結晶を製造できることが開示されている(特許文献1参照)。   As one of the methods for obtaining a high resistivity silicon wafer by using the CZ method to prevent the decrease in resistivity due to the formation of such oxygen donors, a silicon single crystal is formed so that the interstitial oxygen concentration is lowered during crystal growth. A method of manufacturing is disclosed. For example, by using a synthetic quartz crucible to grow a single crystal by the MCZ method (a method in which a magnetic field is applied to a silicon melt in the CZ method), the amount of oxygen dissolved in the single crystal is controlled to be 10,000 Ω · cm or more. It is disclosed that a silicon single crystal having a high resistivity can be manufactured (see Patent Document 1).

また、CZ法によって高抵抗率ウェーハを製造する別の方法として、酸素ドナーが形成される現象を逆に利用することによって、高抵抗率シリコンウェーハを製造する方法も提案されている。すなわち、低不純物濃度で低酸素濃度のP型シリコンウェーハに400〜500℃の熱処理を行って酸素ドナーを発生させる。この発生した酸素ドナーは電子を放出するN型であるから、これによりシリコンウェーハ中のP型不純物の抵抗率に対する寄与を打ち消してウェーハの導電型をN型化することによって、高抵抗率N型シリコンウェーハを製造することができる(特許文献2参照)。   As another method for producing a high resistivity wafer by the CZ method, a method for producing a high resistivity silicon wafer by utilizing the phenomenon that an oxygen donor is formed has been proposed. That is, a heat treatment at 400 to 500 ° C. is performed on a P-type silicon wafer having a low impurity concentration and a low oxygen concentration to generate an oxygen donor. Since the generated oxygen donor is an N-type that emits electrons, this cancels the contribution to the resistivity of the P-type impurity in the silicon wafer and changes the conductivity type of the wafer to the N-type, thereby increasing the resistivity N-type. A silicon wafer can be manufactured (see Patent Document 2).

CZ法により高抵抗率のウェーハを製造するさらに別の方法として、CZ法により抵抗率が100Ω・cm以上で初期格子間酸素濃度が10〜25ppmaであるシリコン単結晶棒を育成して、該シリコン単結晶棒をウェーハに加工し、その後、該ウェーハに酸素析出熱処理を行なって格子間酸素を析出させることにより、ウェーハ中の残留格子間酸素濃度を8ppma以下としてシリコンウェーハを製造する方法も提案されている(特許文献3参照)。   As yet another method for producing a high resistivity wafer by the CZ method, a silicon single crystal rod having a resistivity of 100 Ω · cm or more and an initial interstitial oxygen concentration of 10 to 25 ppma is grown by the CZ method. There has also been proposed a method of manufacturing a silicon wafer by processing a single crystal rod into a wafer and then subjecting the wafer to oxygen precipitation heat treatment to precipitate interstitial oxygen, thereby reducing the residual interstitial oxygen concentration in the wafer to 8 ppma or less. (See Patent Document 3).

また、CZ法により、抵抗率が100Ω・cmで初期格子間酸素濃度が5〜10ppmaであるシリコン単結晶棒を育成することにより、酸素ドナーの発生による抵抗率低下の影響がほとんどない高抵抗率CZシリコンウェーハを製造することができることが開示されている(特許文献4参照)。   Further, by growing a silicon single crystal rod having a resistivity of 100 Ω · cm and an initial interstitial oxygen concentration of 5 to 10 ppma by the CZ method, a high resistivity with almost no influence of resistivity reduction due to the generation of oxygen donors. It is disclosed that a CZ silicon wafer can be manufactured (see Patent Document 4).

しかし、以上のようなCZ法によって製造されたシリコンウェーハであっても、FZ法により製造されたシリコンウェーハと比較すると、デバイス製造工程、例えば酸化膜形成、不純物拡散、配線工程における熱処理を加えるとウェーハの抵抗率が低下する問題が依然として存在する。従って、デバイス製造工程で抵抗率が低下することのないFZ法により育成された高抵抗率のシリコン単結晶であって、直径が例えば200mm以上の大口径のものを製造する方法の開発が望まれていた。   However, even if the silicon wafer manufactured by the CZ method as described above is compared with the silicon wafer manufactured by the FZ method, the heat treatment in the device manufacturing process, for example, oxide film formation, impurity diffusion, wiring process is added. There still remains the problem of reducing the resistivity of the wafer. Accordingly, it is desired to develop a method for manufacturing a high resistivity silicon single crystal grown by the FZ method that does not lower the resistivity in the device manufacturing process and having a large diameter of, for example, 200 mm or more. It was.

FZ法による直径200mmのシリコン単結晶の製造方法としては、直径145mm以上の多結晶シリコンをシリコン原料棒とする方法が開示されている(特許文献5参照)。   As a method for producing a silicon single crystal having a diameter of 200 mm by the FZ method, a method using polycrystalline silicon having a diameter of 145 mm or more as a silicon raw material rod is disclosed (see Patent Document 5).

通常は出来るだけ直径の大きいシリコン原料棒からシリコン単結晶を製造する方が生産性等の点で有利であるが、直径の大きい、特に直径160mm以上の多結晶シリコンを製造するのは極めて困難である。また、多結晶シリコンは大口径になると均一な粒界組織にならないという欠点を有するものとなる。従って、例えば直径160mmの多結晶シリコン原料棒を使用してFZ法により直径200mmのシリコン単結晶を製造した場合、1回のFZ法によるゾーニングでは無転位にならず、ゾーニングを繰り返す必要があるため、製造歩留りが極めて低くなってしまうという問題がある。また、大口径の多結晶シリコンは単価が極めて高いという欠点も有する。   Usually, it is more advantageous in terms of productivity to produce a silicon single crystal from a silicon raw material rod having a diameter as large as possible. However, it is extremely difficult to produce polycrystalline silicon having a large diameter, particularly a diameter of 160 mm or more. is there. Polycrystalline silicon has a drawback that it does not have a uniform grain boundary structure when the diameter is large. Therefore, for example, when a polycrystalline silicon raw material rod having a diameter of 160 mm is used to produce a silicon single crystal having a diameter of 200 mm by the FZ method, zoning by the FZ method does not result in no dislocation and it is necessary to repeat the zoning. There is a problem that the manufacturing yield is extremely low. In addition, large-diameter polycrystalline silicon has a disadvantage that the unit price is extremely high.

なお、CZ法で製造された抵抗率が10〜15Ω・cm程度のシリコン単結晶棒に関しては、結晶成長時の冷却条件の違いにより、軸方向で酸素析出物の量等に差が生じている場合があり、それを軸方向で均一にするために、CZ法により上部から下部に向けて格子間酸素濃度を増大させたシリコン単結晶棒を引き上げ、これをFZ法を用いて再結晶化させる方法が開示されている(特許文献6参照)。   For silicon single crystal rods having a resistivity of about 10 to 15 Ω · cm manufactured by the CZ method, there is a difference in the amount of oxygen precipitates in the axial direction due to the difference in cooling conditions during crystal growth. In some cases, in order to make it uniform in the axial direction, a silicon single crystal rod having an increased interstitial oxygen concentration is pulled up from the top to the bottom by the CZ method, and this is recrystallized using the FZ method. A method is disclosed (see Patent Document 6).

特開平5−58788号公報Japanese Patent Laid-Open No. 5-58788 特公平8−10695号公報Japanese Patent Publication No. 8-10695 国際公開第00/55397号パンフレットInternational Publication No. 00/55397 Pamphlet 特開2003−68744号公報JP 2003-68744 A 特開2003−55089号公報JP 2003-55089 A 特開平5−43382号公報JP-A-5-43382

本発明は上記問題点に鑑みてなされたものであって、本発明の目的は、大口径で抵抗率1000Ω・cm以上の高抵抗率のP型またはN型の高品質なシリコン単結晶を、デバイス製造工程で抵抗率が低下することのないFZ法により低コスト且つ高歩留まりで製造する方法を提供することにある。   The present invention has been made in view of the above problems, and an object of the present invention is to provide a high-resistance P-type or N-type high-quality silicon single crystal having a large diameter and a resistivity of 1000 Ω · cm or more. An object of the present invention is to provide a low-cost and high-yield manufacturing method by the FZ method in which the resistivity does not decrease in the device manufacturing process.

上記目的達成のため、本発明は、FZ法によるシリコン単結晶の製造方法であって、CZ法により製造された抵抗率が1000Ω・cm以上のP型またはN型のシリコン結晶棒をシリコン原料棒として、該シリコン原料棒をFZ法により抵抗率が1000Ω・cm以上のP型またはN型のシリコン単結晶に再結晶化させることを特徴とするシリコン単結晶の製造方法を提供する。 In order to achieve the above object, the present invention is a method for producing a silicon single crystal by FZ method, wherein a P-type or N-type silicon crystal rod having a resistivity of 1000 Ω · cm or more produced by CZ method is used as a silicon raw material rod. as, that provides a method for manufacturing a silicon single crystal, characterized in that resistivity of the silicon raw material rod by FZ method is recrystallized in 1000 [Omega] · cm or more P-type or N-type silicon single crystal.

このように、CZ法により製造された抵抗率が1000Ω・cm以上のP型またはN型のシリコン結晶棒をシリコン原料棒とすれば、大口径のシリコン原料棒であっても多結晶シリコンのものよりも結晶品質がはるかに高く且つ安価に製造できるものなので、これをFZ法により抵抗率が1000Ω・cm以上のP型またはN型のシリコン単結晶に再結晶化させれば、高抵抗率で且つデバイス製造工程でも抵抗率が低下することのない高品質な大口径シリコン単結晶を、低コストで且つ高歩留まりで製造することができる。   As described above, if a P-type or N-type silicon crystal rod having a resistivity of 1000 Ω · cm or more manufactured by the CZ method is used as a silicon raw material rod, even a large-diameter silicon raw material rod is made of polycrystalline silicon. The crystal quality is much higher than that of the above and can be manufactured at low cost. If this is recrystallized into a P-type or N-type silicon single crystal having a resistivity of 1000 Ω · cm or more by the FZ method, the resistivity is high. In addition, a high-quality large-diameter silicon single crystal whose resistivity does not decrease even in the device manufacturing process can be manufactured at a low cost and with a high yield.

この場合、前記再結晶化を行なう際に、前記シリコン原料棒の導電型とは反対の導電型の不純物をガスドープすることにより、前記シリコン原料棒を抵抗率が3000Ω・cm以上のP型またはN型のシリコン単結晶に再結晶化させることが好ましい。
このように、再結晶化を行なう際に、シリコン原料棒の導電型とは反対の導電型の不純物(ドーパント)をガスドープすれば、元々シリコン原料棒にドープされていたドーパントの抵抗率に対する寄与を減少させるまたは打ち消すことができるので、これによって抵抗率が3000Ω・cm以上の高抵抗率のP型またはN型のシリコン単結晶を極めて容易に製造することができる。
In this case, when the recrystallization is performed, the silicon raw material rod is doped with an impurity having a conductivity type opposite to the conductivity type of the silicon raw material rod, so that the silicon raw material rod has a resistivity of 3000 Ω · cm or more. it is not preferable to recrystallize the type of the silicon single crystal.
Thus, when performing recrystallization, if the impurity (dopant) of the conductivity type opposite to the conductivity type of the silicon raw material rod is gas-doped, the contribution to the resistivity of the dopant originally doped in the silicon raw material rod can be achieved. Since this can be reduced or canceled out, a high resistivity P-type or N-type silicon single crystal having a resistivity of 3000 Ω · cm or more can be produced very easily.

また、前記再結晶化させるシリコン単結晶の直径を200mm以上とすることができる。
このように、本発明ではCZ法により製造された大口径であっても結晶品質が高く且つ安価なシリコン原料棒を使用するので、最終的に製造する高品質シリコン単結晶の直径を低コスト且つ高歩留まりで容易に200mm以上とすることができ、これによって高性能半導体デバイスを低コストで製造するのに適する大口径で高抵抗率のFZシリコンウェーハを提供できる。
Further, the diameter of the silicon single crystal to the recrystallization Ru can be at least 200 mm.
As described above, in the present invention, since a silicon raw material rod having a high crystal quality and a low price even with a large diameter manufactured by the CZ method is used, the diameter of a high-quality silicon single crystal to be finally manufactured can be reduced at a low cost. A high yield and a high resistivity FZ silicon wafer suitable for manufacturing a high-performance semiconductor device at low cost can be provided.

この場合、前記シリコン原料棒の直径を150mm以上とすることが好ましい。
このように、CZ法で製造したシリコン原料棒の直径を150mm以上とすれば、直径200mm以上の大口径の高品質FZシリコン単結晶を高歩留まりで且つ容易に製造できる。なお、例えば最終的に製造するシリコン単結晶の直径を200mmとする場合には、シリコン原料棒の直径を210mm以下とするのが好ましい。直径が210mmより大きい場合は、そのような太い原料棒を溶融するためにそれだけ高電力が必要となるので、200mm用の誘導加熱コイルではコイルから放電が生じるおそれがあり、またゾーニングの際の溶融帯に対する原料の供給スピードが遅くなりすぎ、溶融状態が悪化してネック部が切れる問題が生じるおそれがあるので好ましくない。
In this case, it is not preferable that the diameter of the silicon raw material rod and more than 150 mm.
Thus, if the diameter of the silicon raw material rod manufactured by the CZ method is 150 mm or more, a high-quality FZ silicon single crystal having a large diameter of 200 mm or more can be easily manufactured with a high yield. For example, when the diameter of the finally produced silicon single crystal is 200 mm, the diameter of the silicon raw material rod is preferably 210 mm or less. If the diameter is larger than 210 mm, high electric power is required to melt such a thick raw material rod. Therefore, an induction heating coil for 200 mm may cause discharge from the coil, and also melt during zoning. Since the supply speed of the raw material with respect to a belt | band | zone becomes too late, there exists a possibility that the molten state may deteriorate and the neck part may be cut off, it is not preferable.

また、前記シリコン単結晶に含まれる酸素濃度を1ppma(JEIDA)以下とすることが好ましい。
このように、FZ法により再結晶化させることにより、シリコン単結晶に含まれる酸素濃度を1ppma以下とすることが容易にできるので、この単結晶に350〜500℃程度の熱処理を施しても酸素ドナーの形成は確実に防止される。従って、デバイス製造工程において抵抗率が低下することが確実にない高抵抗率のFZウェーハを作製可能なシリコン単結晶を製造できる。
Moreover, it is not preferable that the oxygen concentration in the silicon single crystal 1 ppma (JEIDA) or less.
Thus, by recrystallizing by the FZ method, the oxygen concentration contained in the silicon single crystal can be easily reduced to 1 ppma or less. Therefore, even if the single crystal is subjected to heat treatment at about 350 to 500 ° C. Donor formation is reliably prevented. Accordingly, it is possible to manufacture a silicon single crystal capable of manufacturing a high-resistivity FZ wafer in which the resistivity is not reliably lowered in the device manufacturing process.

また、前記再結晶化を行なう際に、成長炉のチャンバー内雰囲気の窒素濃度を0.2〜0.5%とすることが好ましい。
このように、再結晶化を行なう際に、成長炉のチャンバー内雰囲気の窒素濃度を0.2〜0.5%とすれば、再結晶化したシリコン単結晶には適量の窒素がドープされ、シリコン原料棒内に存在するFPD(Flow Pattern Defect)やスワール欠陥を消滅させることができるので、より高品質なシリコン単結晶が製造できる。
Further, when performing the recrystallization, it has preferred to make the nitrogen concentration of the growth furnace chamber atmosphere 0.2 to 0.5%.
Thus, when performing recrystallization, if the nitrogen concentration of the atmosphere in the chamber of the growth furnace is 0.2 to 0.5%, the recrystallized silicon single crystal is doped with an appropriate amount of nitrogen, Since FPD (Flow Pattern Defect) and swirl defects existing in the silicon raw material rod can be eliminated, a higher quality silicon single crystal can be manufactured.

また、前記再結晶化を行なう際に、前記シリコン原料棒の低抵抗側から高抵抗側に向かってゾーニングすることにより、前記シリコン原料棒を再結晶化させることが好ましい。
このように、FZ法による再結晶化を行なう際に、シリコン原料棒の低抵抗側から高抵抗側に向かってゾーニングすることによりシリコン原料棒を再結晶化させれば、低抵抗側から高抵抗側にドーパントが偏析するので、再結晶化したシリコン単結晶棒の軸方向の抵抗率分布を、元々のシリコン原料棒の軸方向の抵抗率分布よりも均一にすることができる。
Further, the in performing the recrystallization, the by zoning toward the high-resistance from a low resistance side of the silicon feed rod, have preferably be recrystallized said silicon raw material rod.
Thus, when performing recrystallization by the FZ method, if the silicon raw material rod is recrystallized by zoning from the low resistance side to the high resistance side of the silicon raw material rod, the high resistance from the low resistance side. Since the dopant segregates on the side, the resistivity distribution in the axial direction of the recrystallized silicon single crystal rod can be made more uniform than the resistivity distribution in the axial direction of the original silicon raw material rod.

本発明に従い、CZ法により製造された抵抗率が1000Ω・cm以上のP型またはN型のシリコン結晶棒をシリコン原料棒として、これをFZ法により抵抗率が1000Ω・cm以上のP型またはN型のシリコン単結晶に再結晶化させれば、高抵抗率で且つデバイス製造工程でも抵抗率が低下することのない高品質な大口径シリコン単結晶を、低コスト且つ高歩留まりで製造することができる。これによって、高性能半導体デバイスを低コストで製造するのに適する大口径で高抵抗率のFZシリコンウェーハを提供できる。   According to the present invention, a P-type or N-type silicon crystal rod having a resistivity of 1000 Ω · cm or more manufactured by the CZ method is used as a silicon raw material rod, and this is used as a P-type or N-type having a resistivity of 1000 Ω · cm or more by the FZ method. Recrystallization into a single-crystal silicon type enables high-quality, large-diameter silicon single crystals that do not decrease in resistivity even in the device manufacturing process to be manufactured at low cost and with high yield. it can. As a result, it is possible to provide a large-diameter, high-resistivity FZ silicon wafer suitable for manufacturing high-performance semiconductor devices at low cost.

以下、本発明について詳述する。
前述のように、近年大口径化の要求が強い高抵抗率のシリコンウェーハの材料として、CZ法により製造されたシリコン単結晶が使われるようになってきたが、デバイス製造工程での酸素ドナーの形成によるウェーハの抵抗率の低下の問題が依然として存在していた。特に、高抵抗率のウェーハの場合は、酸素ドナーの形成がわずかであってもその抵抗率に与える影響は大きいので、このような酸素ドナーの形成を防止する必要性が高い。
一方、FZ法により製造されたシリコン単結晶は酸素濃度が極めて低いものとなるので、このような抵抗率の変化は発生しないが、従来FZ法においてシリコン原料棒として用いられていた多結晶シリコン棒は大口径のものを高品質で安価に製造するのが困難であり、1回のゾーニングでの無転位化の成功率が低く、このことはFZシリコン単結晶の製造歩留まりの低下と高コスト化とを招いていた。
Hereinafter, the present invention will be described in detail.
As described above, a silicon single crystal manufactured by the CZ method has been used as a material for a high resistivity silicon wafer which has recently been required to have a large diameter, but the oxygen donor in the device manufacturing process has been used. The problem of wafer resistivity reduction due to formation still existed. In particular, in the case of a high resistivity wafer, even if the formation of oxygen donor is slight, the influence on the resistivity is great, and thus it is highly necessary to prevent the formation of such oxygen donor.
On the other hand, since the silicon single crystal manufactured by the FZ method has a very low oxygen concentration, such a change in resistivity does not occur, but a polycrystalline silicon rod that has been conventionally used as a silicon raw material rod in the FZ method. Is difficult to manufacture high-quality products with large diameter at low cost, and the success rate of dislocation-free in one zoning is low, which means that the production yield and cost of FZ silicon single crystals are reduced. Was invited.

本発明者らは、抵抗率が1000Ω・cm以上のFZシリコン単結晶を製造する際に、CZ法により製造された抵抗率が1000Ω・cm以上のP型またはN型のシリコン結晶棒をシリコン原料棒として、該シリコン原料棒をFZ法により再結晶化させれば、CZ法により製造された酸素濃度の高いシリコン結晶を原料棒として用いたとしても、FZ中に、原料棒中の酸素を飛散させることができるので、デバイス製造工程で酸素ドナーの発生しないウェーハを作製できるシリコン単結晶とすることができることに想到した。さらに、CZ法で製造された大口径のシリコン結晶の原料棒は多結晶シリコンのものよりもはるかに高品質であるから、これを用いればゾーニングの回数の減少及びゾーニングによる無転位化の成功率の向上が達成できるし、しかも同じ大口径の多結晶棒よりもむしろ安価であるから、結果として高品質のシリコン単結晶を低コスト且つ高歩留まりで製造することができることに想到し、本発明を完成させた。   When the present inventors produce an FZ silicon single crystal having a resistivity of 1000 Ω · cm or more, a P-type or N-type silicon crystal rod produced by the CZ method and having a resistivity of 1000 Ω · cm or more is used as a silicon raw material. If the silicon raw material rod is recrystallized by the FZ method as a rod, the oxygen in the raw material rod is scattered in the FZ even if a silicon crystal with a high oxygen concentration produced by the CZ method is used as the raw material rod. As a result, it was conceived that a silicon single crystal capable of producing a wafer that does not generate an oxygen donor in the device manufacturing process can be obtained. Furthermore, since the raw material rod of large-diameter silicon crystal manufactured by the CZ method is much higher quality than that of polycrystalline silicon, if this is used, the number of times of zoning is reduced and the success rate of dislocation-free by zoning In addition, it is cheaper than the same large-diameter polycrystalline rod, and as a result, it is conceived that a high-quality silicon single crystal can be produced at a low cost and with a high yield. Completed.

以下では、本発明の実施の形態について図面を用いて説明するが、本発明はこれに限定されるものではない。   Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

図1は、本発明に係るシリコン単結晶の製造に用いるFZ単結晶製造装置の一例を示す模式的部分断面図である。
まず、FZ法によるシリコン単結晶の製造に用いるシリコン原料棒となるシリコン結晶棒をCZ法により育成する。例えば導電型がP型、直径200mmのシリコン結晶棒を育成する場合、例えば口径24インチ(600mm)の石英ルツボに150kgのシリコン多結晶を充填し、抵抗率が1000Ω・cm以上の所望の抵抗率となるようにドーパントとして所定量のボロンやガリウム等のP型のドーパントを石英ルツボ内に投入する。ドーパントとしては、例えばボロンを高濃度にドープしたシリコン片を用いることができる。なお、導電型をN型とする場合には、リン、ヒ素、アンチモン等のN型のドーパントを投入すればよい。
FIG. 1 is a schematic partial sectional view showing an example of an FZ single crystal manufacturing apparatus used for manufacturing a silicon single crystal according to the present invention.
First, a silicon crystal rod used as a silicon raw material rod used for manufacturing a silicon single crystal by the FZ method is grown by the CZ method. For example, when a silicon crystal rod having a conductivity type of P type and a diameter of 200 mm is grown, for example, a quartz crucible having a diameter of 24 inches (600 mm) is filled with 150 kg of silicon polycrystal, and the resistivity is 1000 Ω · cm or more. As a dopant, a predetermined amount of P-type dopant such as boron or gallium is introduced into the quartz crucible. As the dopant, for example, a silicon piece doped with boron at a high concentration can be used. Note that when the conductivity type is N-type, an N-type dopant such as phosphorus, arsenic, or antimony may be added.

そして、その後、ヒータによりシリコン多結晶を加熱溶融した原料融液に種結晶を浸し、種結晶とルツボを反対方向に回転させながら所定の成長速度で例えば直径205mm、直胴長さ150cmのシリコン結晶を成長させる。このとき、シリコン結晶は抵抗率が目標とする1000Ω・cm以上の抵抗率に制御されたものであればよく、その他の製造条件や特性、例えば酸素濃度、COP(Crystal Originated Particle)密度、FPD密度は特に限定されない。なお、結晶方位としては、最終的に製造するFZシリコン単結晶と同じとすることが好ましい。また、育成したシリコン結晶中のボロンやリン等のドーパント濃度は、例えば1×1013atoms/cm以下である。 Then, a seed crystal is immersed in a raw material melt obtained by heating and melting silicon polycrystal with a heater, and a silicon crystal having a diameter of, for example, 205 mm and a straight body length of 150 cm is rotated at a predetermined growth rate while rotating the seed crystal and the crucible in opposite directions. Grow. At this time, the silicon crystal only needs to have a resistivity controlled to a target resistivity of 1000 Ω · cm or more, and other manufacturing conditions and characteristics such as oxygen concentration, COP (Crystal Originated Particle) density, FPD density. Is not particularly limited. The crystal orientation is preferably the same as that of the finally produced FZ silicon single crystal. The concentration of dopants such as boron and phosphorus in the grown silicon crystal is, for example, 1 × 10 13 atoms / cm 3 or less.

なお、本発明ではCZ法により製造された大口径であっても結晶品質が高く且つ安価なシリコン原料棒を使用するので、上記のように最終的に製造する高品質FZシリコン単結晶の直径を200mm以上とする場合でも、低コスト且つ高歩留まりで容易に製造を行なうことができるので好ましい。
その場合、CZ法で製造したシリコン原料棒の直径を150mm以上とすれば、直径200mm以上の大口径の高品質FZシリコン単結晶を高歩留まりで且つ容易に製造できるので好ましい。なお、例えば最終的に製造するシリコン単結晶の直径を200mmとする場合には、シリコン原料棒の直径を210mm以下とするのが好ましい。直径が210mmより大きい場合は、そのような太い原料棒を溶融するためにそれだけ高電力が必要となるので、200mm用の誘導加熱コイルではコイルから放電が生じるおそれがあり、またゾーニングの際の上軸下降速度(溶融帯に対する原料の供給スピード)が遅くなりすぎ、溶融状態が悪化してネック部が切れる問題が生じるおそれがあるので好ましくない。但し、原料棒の直径の好ましい上限値は、製造するFZシリコン単結晶の直径に応じて定めることができる。
In the present invention, since a silicon raw material rod having a high crystal quality and a low cost is used even with a large diameter manufactured by the CZ method, the diameter of the high-quality FZ silicon single crystal finally manufactured as described above is set. Even when it is 200 mm or more, it is preferable because it can be easily produced at a low cost and with a high yield.
In that case, it is preferable that the diameter of the silicon raw material rod produced by the CZ method is 150 mm or more because a high-quality FZ silicon single crystal having a large diameter of 200 mm or more can be easily produced with a high yield. For example, when the diameter of the finally produced silicon single crystal is 200 mm, the diameter of the silicon raw material rod is preferably 210 mm or less. If the diameter is larger than 210 mm, high electric power is required to melt such a thick raw material rod. Therefore, the induction heating coil for 200 mm may cause discharge from the coil. This is not preferable because the shaft lowering speed (feeding speed of the raw material to the molten zone) becomes too slow and there is a possibility that the molten state deteriorates and the neck portion is cut. However, the preferable upper limit of the diameter of the raw material rod can be determined according to the diameter of the FZ silicon single crystal to be manufactured.

次に、こうしてCZ法で育成したシリコン結晶の抵抗率、酸素濃度、ライフタイムを測定し、またスリップ転位の有無を確認する。スリップ転位が存在していると、シリコン結晶棒をFZのシリコン原料棒としてFZ単結晶製造装置にセットする時やFZ法でシリコン単結晶を再結晶化中に原料棒落下の原因となり得るので、スリップ転位がある場合は、スリップ転位の部分を予め取り除く必要がある。なお、このようなスリップ転位以外の結晶欠陥は存在していても特に問題はなく、シリコン結晶棒が完全に高品質な単結晶となっているものでなくともよい。すなわち、このようにCZ法で製造されたシリコン結晶棒であれば、従来FZ法のシリコン原料棒として用いられていたシリコン多結晶原料棒と比較して結晶性がはるかに高いので、FZ法により再結晶化して得られるシリコン単結晶は従来のものより高品質とできるし、例えば所望の品質のシリコン単結晶を得るために従来ではゾーニングを複数回行なう必要がある場合であっても、本発明では1回のゾーニングで所望の品質が得られる確率がはるかに高いものとなる。   Next, the resistivity, oxygen concentration, and lifetime of the silicon crystal thus grown by the CZ method are measured, and the presence or absence of slip dislocation is confirmed. If slip dislocations exist, it may cause the raw material rod to fall when the silicon crystal rod is set as an FZ silicon raw material rod in an FZ single crystal manufacturing apparatus or during recrystallization of a silicon single crystal by the FZ method. If there is slip dislocation, it is necessary to remove the slip dislocation in advance. It should be noted that there is no particular problem even if such crystal defects other than slip dislocations exist, and the silicon crystal rod does not have to be a completely high-quality single crystal. That is, the silicon crystal rod manufactured by the CZ method in this way has a crystallinity much higher than that of the silicon polycrystalline material rod conventionally used as the silicon raw material rod of the FZ method. The silicon single crystal obtained by recrystallization can be of higher quality than the conventional one. For example, even in the case where it is conventionally necessary to perform zoning a plurality of times in order to obtain a silicon single crystal of desired quality, the present invention Then, the probability that a desired quality can be obtained by one zoning is much higher.

次に、こうしてCZ法により得られたシリコン結晶棒を円筒研削後、FZ法で溶融を開始する部分をコーン形状に加工し、その後、加工歪みを除去するために表面のエッチングを行なう。このシリコン結晶棒は、例えばボロンをドープした場合には、シリコン結晶が成長するに従ってドープされるボロン濃度が高くなるので、抵抗率は低くなる。その結果、シリコン結晶棒には軸方向に抵抗率分布が生じている。従って、シリコン結晶棒の一端をコーン形状に加工してコーン部を形成する際に、シリコン結晶棒の低抵抗側から高抵抗側に向かってゾーニングするときはシリコン結晶棒の低抵抗側をコーン形状に加工し、シリコン結晶棒の高抵抗側から低抵抗側に向かってゾーニングするときは、シリコン結晶棒の高抵抗側をコーン形状に加工する。   Next, after cylindrical grinding of the silicon crystal rod thus obtained by the CZ method, the portion where melting starts by the FZ method is processed into a cone shape, and then the surface is etched to remove the processing strain. For example, when the silicon crystal rod is doped with boron, the concentration of boron to be doped increases as the silicon crystal grows, so that the resistivity decreases. As a result, the silicon crystal rod has a resistivity distribution in the axial direction. Therefore, when processing one end of a silicon crystal rod into a cone shape to form a cone part, when zoning from the low resistance side of the silicon crystal rod to the high resistance side, the low resistance side of the silicon crystal rod is cone shaped When zoning from the high resistance side of the silicon crystal rod toward the low resistance side, the high resistance side of the silicon crystal rod is processed into a cone shape.

そして、このようにCZ法により製造された抵抗率が1000Ω・cm以上のP型またはN型のシリコン結晶棒を、FZ成長炉のチャンバー内に設置された図1に示すFZ単結晶製造装置1の上軸4の上部保持冶具6にネジ等で固定してシリコン原料棒2とし、下軸8の下部保持冶具10には種結晶12を取り付ける。   Then, an FZ single crystal manufacturing apparatus 1 shown in FIG. 1 in which a P-type or N-type silicon crystal rod having a resistivity of 1000 Ω · cm or more manufactured in this way is installed in a chamber of an FZ growth reactor. A silicon raw material rod 2 is fixed to the upper holding jig 6 of the upper shaft 4 with screws or the like, and a seed crystal 12 is attached to the lower holding jig 10 of the lower shaft 8.

次に、シリコン原料棒2のコーン部の下端をカーボンリング(不図示)で予備加熱する。その後、チャンバー下部より窒素ガスを含んだArガスを供給しチャンバー上部より排気して、例えば炉内圧力を0.20MPa、Arガスの流量を50l/min、チャンバー内窒素濃度を0.5%とする。そして、シリコン原料棒2を誘導加熱コイル(高周波コイル)14で加熱溶融した後、コーン部先端を種結晶12に融着させ、絞り16により無転位化し、上軸4と下軸8を回転させながらシリコン原料棒2を例えば2.3mm/minの成長速度で下降させることで溶融帯(メルト)18をシリコン原料棒上端まで移動させてゾーニングし、シリコン原料棒2を再結晶化してシリコン単結晶3を成長させる。このとき、シリコン原料棒2を育成する際に回転中心となる軸4と、再結晶化の際に単結晶の回転中心となる軸8とをずらして(偏芯させて)単結晶を育成することが好ましい。このように両中心をずらすことにより再結晶化の際に溶融状態を攪拌させ、製造する単結晶の面内抵抗率分布等の品質を均一化することができる。偏芯量は例えば単結晶の直径に応じて設定すればよい。   Next, the lower end of the cone portion of the silicon raw material rod 2 is preheated with a carbon ring (not shown). Thereafter, Ar gas containing nitrogen gas is supplied from the bottom of the chamber and exhausted from the top of the chamber. For example, the furnace pressure is 0.20 MPa, the Ar gas flow rate is 50 l / min, and the nitrogen concentration in the chamber is 0.5%. To do. After the silicon raw material rod 2 is heated and melted by the induction heating coil (high frequency coil) 14, the tip of the cone portion is fused to the seed crystal 12, the dislocation is made free by the diaphragm 16, and the upper shaft 4 and the lower shaft 8 are rotated. However, the silicon raw material rod 2 is lowered at a growth rate of, for example, 2.3 mm / min to move the melting zone (melt) 18 to the upper end of the silicon raw material rod and perform zoning, and the silicon raw material rod 2 is recrystallized to form a silicon single crystal. Grow 3 At this time, a single crystal is grown by shifting (eccentrically) the axis 4 serving as the center of rotation when growing the silicon raw material rod 2 and the axis 8 serving as the center of rotation of the single crystal during recrystallization. It is preferable. By shifting both centers in this way, the molten state can be stirred during recrystallization, and the quality of the in-plane resistivity distribution and the like of the single crystal to be produced can be made uniform. What is necessary is just to set eccentricity according to the diameter of a single crystal, for example.

こうして、CZ法により製造されたシリコン原料棒中に不可避的に含まれる酸素を溶融帯中に飛散させることができるので、FZ単結晶中の酸素濃度を極めて低いものとできる、その結果350〜500℃の熱処理が施されても酸素ドナーが発生しないだけでなく、COPに代表される酸素起因欠陥が極めて低密度なシリコン単結晶とできる。   In this way, oxygen inevitably contained in the silicon raw material rod produced by the CZ method can be scattered in the melting zone, so that the oxygen concentration in the FZ single crystal can be made extremely low. As a result, 350-500 Even if heat treatment at 0 ° C. is performed, not only oxygen donors are generated, but also a silicon single crystal with extremely low density of oxygen-induced defects typified by COP.

なお、上記のようにチャンバー内を窒素を含む雰囲気にすれば、シリコン単結晶中に窒素がドープされ、シリコン原料棒2の内部に存在したFPDやスワール欠陥が消滅するのでより高品質のシリコン単結晶を成長させることができるので好ましい。この場合、雰囲気中の窒素濃度は上記の0.5%に限らず、0.2〜0.5%とすれば、上記の欠陥を消滅させるのに適当な濃度の窒素がドープされるので好ましい。また、窒素ガスの代わりにアンモニア、ヒドラジン、三フッ化窒素等の窒素を含む化合物ガスを用いてもよい。このときシリコン単結晶にドープされる窒素濃度は、例えば3×1014atoms/cm程度である。 If the atmosphere in the chamber is nitrogen-containing as described above, the silicon single crystal is doped with nitrogen, and the FPD and swirl defects existing inside the silicon raw material rod 2 disappear, so that a higher quality silicon single crystal can be obtained. This is preferable because crystals can be grown. In this case, the nitrogen concentration in the atmosphere is not limited to the above 0.5%, and if it is 0.2 to 0.5%, it is preferable because nitrogen is doped at an appropriate concentration to eliminate the above defects. . Further, instead of nitrogen gas, a compound gas containing nitrogen such as ammonia, hydrazine, or nitrogen trifluoride may be used. At this time, the concentration of nitrogen doped in the silicon single crystal is, for example, about 3 × 10 14 atoms / cm 3 .

また、再結晶化の際に、シリコン原料棒2の低抵抗側をコーン部として低抵抗側から高抵抗側に向かってゾーニングすれば、シリコン単結晶3の軸方向の抵抗率分布をシリコン原料棒2の軸方向の抵抗率分布よりも均一にすることができるので、ここからシリコンウェーハを作製すれば、それらはウェーハ間で抵抗率のバラツキがないものとできるので好ましい。また逆に、シリコン原料棒2の高抵抗側をコーン部として高抵抗側から低抵抗側に向かってゾーニングすれば、シリコン単結晶3の軸方向の抵抗率分布を、シリコン原料棒2の軸方向の抵抗率分布よりも大きな傾きをもつ抵抗率分布とすることもでき、これによってウェーハ間で抵抗率がより大きく異なる複数のシリコンウェーハを製造することもできる。これにより種々の抵抗率規格に対応することができる。   Further, when recrystallizing, if the zoning is performed from the low resistance side to the high resistance side with the low resistance side of the silicon raw material rod 2 as the cone portion, the resistivity distribution in the axial direction of the silicon single crystal 3 is obtained. Since it can be made more uniform than the resistivity distribution in the axial direction of 2, it is preferable to produce silicon wafers from here because they can be made to have no variation in resistivity between the wafers. Conversely, if the zoning is performed from the high resistance side to the low resistance side with the high resistance side of the silicon raw material rod 2 as the cone portion, the resistivity distribution in the axial direction of the silicon single crystal 3 is changed to the axial direction of the silicon raw material rod 2. It is also possible to obtain a resistivity distribution having a larger slope than the resistivity distribution, thereby making it possible to manufacture a plurality of silicon wafers having a resistivity that differs greatly between the wafers. Thereby, it can respond to various resistivity standards.

さらに、再結晶化を行なう際に、シリコン原料棒の導電型とは反対の導電型の不純物(ドーパント)をガスドープすれば、元々シリコン原料棒にドープされていたドーパントの抵抗率に対する寄与を減少させるまたは打ち消すことができるので、これによって抵抗率が3000Ω・cm以上の高抵抗率のP型またはN型のシリコン単結晶を極めて容易に製造することができる。この場合、ドープ量の調整により、シリコン単結晶の導電型を原料棒の導電型と同じものにも反対のものにもできる。   Furthermore, when performing recrystallization, if the impurity (dopant) having a conductivity type opposite to that of the silicon raw material rod is gas-doped, the contribution to the resistivity of the dopant originally doped in the silicon raw material rod is reduced. Alternatively, since it can be canceled out, a high resistivity P-type or N-type silicon single crystal having a resistivity of 3000 Ω · cm or more can be manufactured very easily. In this case, the conductivity type of the silicon single crystal can be made the same as or opposite to the conductivity type of the raw material rod by adjusting the doping amount.

ガスドープは、公知の方法に従いドープガスノズル22から反対導電型のドーパントガスを極微量含むドープガスを所定の流量で溶融帯に吹きつけることにより行なうことができる。例えば、シリコン原料棒がN型であれば、ドーパントガスとしてジボラン(B)をArガス等に極微量だけ含ませたドープガスを用いることができるし、P型であればホスフィン(PH)を用いることができる。 The gas doping can be performed by spraying a dope gas containing a very small amount of a dopant gas of the opposite conductivity type from the dope gas nozzle 22 to the melting zone at a predetermined flow rate according to a known method. For example, if the silicon raw material rod is N-type, a doping gas in which diborane (B 2 H 6 ) is contained in Ar gas or the like as a dopant gas in a trace amount can be used, and if it is P-type, phosphine (PH 3 ) Can be used.

そして、上記のようにFZ法により再結晶化を行なうことにより、シリコン単結晶に含まれる酸素濃度を1ppma以下とすることが容易にできる。このような極めて低い酸素濃度であれば、この単結晶に350〜500℃程度の熱処理を施しても酸素ドナーの形成は確実に防止される。従って、このように製造されたシリコン単結晶は、デバイス製造工程において抵抗率が低下することが確実にない高抵抗率のFZウェーハを作製可能なものとなる。   Then, by performing recrystallization by the FZ method as described above, the oxygen concentration contained in the silicon single crystal can be easily reduced to 1 ppma or less. With such an extremely low oxygen concentration, even if the single crystal is subjected to a heat treatment at about 350 to 500 ° C., the formation of oxygen donors is reliably prevented. Therefore, the silicon single crystal manufactured in this way can produce an FZ wafer having a high resistivity in which the resistivity is not surely lowered in the device manufacturing process.

以下に本発明の実施例をあげてさらに具体的に説明するが、本発明はこれらに限定されるものではない。
(実施例1)
一般的なCZ法の製造方法により、肩部の抵抗率が1500Ω・cmになるようにボロンのドーパントを添加して、導電型P型、直径150mm、直胴長さ150cmのシリコン単結晶を20本製造し、抵抗率、酸素濃度、ライフタイムを測定した。その結果、抵抗率は1000〜1500Ω・cm、酸素濃度は17〜18ppma(JEIDA)、ライフタイムは3000μsecであった。また、全長にわたってスリップ転位がないことを確認した。
Examples of the present invention will be described in more detail below, but the present invention is not limited thereto.
(Example 1)
Boron dopant is added so that the shoulder has a resistivity of 1500 Ω · cm by a general CZ method, and a silicon single crystal having a conductivity type P type, a diameter of 150 mm, and a straight body length of 150 cm is obtained. This was manufactured, and resistivity, oxygen concentration, and lifetime were measured. As a result, the resistivity was 1000-1500 Ω · cm, the oxygen concentration was 17-18 ppma (JEIDA), and the lifetime was 3000 μsec. It was also confirmed that there was no slip dislocation over the entire length.

このCZシリコン単結晶をシリコン原料棒として、FZ法により低抵抗側から高抵抗側へゾーニングを行い、直径205mm、直胴長さ40cmのシリコン単結晶を製造した。
なお、この単結晶の製造の際には、誘導加熱コイルは内側の第一加熱コイルの外径を170mm、外側の第二加熱コイルの外径を280mmのパラレルコイルとし、炉内圧を0.18MPa、Arガス流量を30l/min、窒素ガス濃度を0.3%、成長速度を2.1mm/min、原料回転中心と製品単結晶回転中心のずれ量(偏芯量)を12mmとした。
Using this CZ silicon single crystal as a silicon raw material rod, zoning was performed from the low resistance side to the high resistance side by the FZ method to produce a silicon single crystal having a diameter of 205 mm and a straight body length of 40 cm.
In the production of this single crystal, the induction heating coil is a parallel coil having an inner first heating coil having an outer diameter of 170 mm, an outer second heating coil having an outer diameter of 280 mm, and an in-furnace pressure of 0.18 MPa. The Ar gas flow rate was 30 l / min, the nitrogen gas concentration was 0.3%, the growth rate was 2.1 mm / min, and the amount of deviation (eccentricity) between the material rotation center and the product single crystal rotation center was 12 mm.

そして、このように製造したシリコン単結晶の抵抗率、酸素濃度、ライフタイムを測定した結果、抵抗率は1500〜2000Ω・cm、酸素濃度は0.3ppma(JEIDA)、ライフタイムは5000μsecであった。また、この場合の1パス成功率は60%であった。なお、ここでの1パス成功率とは、上記のように製造したシリコン単結晶のうち、1回のゾーニングで無転位化したものの割合を示すものである。   As a result of measuring the resistivity, oxygen concentration, and lifetime of the silicon single crystal thus manufactured, the resistivity was 1500 to 2000 Ω · cm, the oxygen concentration was 0.3 ppma (JEIDA), and the lifetime was 5000 μsec. . In this case, the one-pass success rate was 60%. Here, the one-pass success rate indicates the proportion of silicon single crystals manufactured as described above that have been dislocation-free by one zoning.

(実施例2)
実施例1と同様に、CZ法により、肩部の抵抗率が1500Ω・cmになるようにボロンのドーパントを添加して、導電型P型、直径200mm、直胴長さ150cmのシリコン単結晶を20本製造し、抵抗率、酸素濃度、ライフタイムを測定した。その結果、抵抗率は1000〜1500Ω・cm、酸素濃度は17〜18ppma、ライフタイムは2000μsecであった。また、全長にわたってスリップ転位がないことを確認した。
(Example 2)
In the same manner as in Example 1, boron dopant was added by the CZ method so that the shoulder resistivity was 1500 Ω · cm, and a silicon single crystal having a conductivity type P type, a diameter of 200 mm, and a straight body length of 150 cm was obtained. Twenty pieces were manufactured, and resistivity, oxygen concentration, and lifetime were measured. As a result, the resistivity was 1000-1500 Ω · cm, the oxygen concentration was 17-18 ppma, and the lifetime was 2000 μsec. It was also confirmed that there was no slip dislocation over the entire length.

このCZシリコン単結晶をシリコン原料棒として、FZ法により低抵抗側から高抵抗側へゾーニングを行い、直径205mm、直胴長さ90cmのシリコン単結晶を製造した。
なお、この単結晶の製造の際には、誘導加熱コイルは内側の第一加熱コイルの外径を220mm、外側の第二加熱コイルの外径を300mmのパラレルコイルとし、炉内圧を0.20MPa、Arガス流量を50l/min、窒素ガス濃度を0.5%、成長速度を2.3mm/min、偏芯量を12mmとした。
Using this CZ silicon single crystal as a silicon raw material rod, zoning was performed from the low resistance side to the high resistance side by the FZ method to produce a silicon single crystal having a diameter of 205 mm and a straight body length of 90 cm.
In the production of this single crystal, the induction heating coil is a parallel coil having an outer diameter of the inner first heating coil of 220 mm, an outer second heating coil of 300 mm, and a furnace pressure of 0.20 MPa. The Ar gas flow rate was 50 l / min, the nitrogen gas concentration was 0.5%, the growth rate was 2.3 mm / min, and the eccentricity was 12 mm.

そして、このように製造したシリコン単結晶の抵抗率、酸素濃度、ライフタイムを測定した結果、抵抗率は1000〜1500Ω・cm、酸素濃度は0.2ppma、ライフタイムは5000μsecであった。また、この場合の1パス成功率は50%であった。   As a result of measuring the resistivity, oxygen concentration, and lifetime of the silicon single crystal thus produced, the resistivity was 1000 to 1500 Ω · cm, the oxygen concentration was 0.2 ppma, and the lifetime was 5000 μsec. In this case, the one-pass success rate was 50%.

(実施例3)
実施例1と同様に、CZ法により、肩部の抵抗率が1500Ω・cmになるようにリンのドーパントを添加して、導電型N型、直径200mm、直胴長さ150cmのシリコン単結晶を20本製造し、抵抗率、酸素濃度、ライフタイムを測定した。その結果、抵抗率は1000〜1500Ω・cm、酸素濃度は17〜18ppma、ライフタイムは2000μsecであった。また、全長にわたってスリップ転位がないことを確認した。
(Example 3)
Similarly to Example 1, a dopant of phosphorus is added by the CZ method so that the shoulder has a resistivity of 1500 Ω · cm, and a silicon single crystal having a conductivity type N type, a diameter of 200 mm, and a straight body length of 150 cm is obtained. Twenty pieces were manufactured, and resistivity, oxygen concentration, and lifetime were measured. As a result, the resistivity was 1000-1500 Ω · cm, the oxygen concentration was 17-18 ppma, and the lifetime was 2000 μsec. It was also confirmed that there was no slip dislocation over the entire length.

このCZシリコン単結晶をシリコン原料棒として、FZ法により低抵抗側から高抵抗側へゾーニングを行い、直径205mm、直胴長さ90cmのシリコン単結晶を製造した。
なお、この単結晶の製造の際には、誘導加熱コイルは内側の第一加熱コイルの外径を220mm、外側の第二加熱コイルの外径を300mmのパラレルコイルとし、炉内圧を0.20MPa、Arガス流量を50l/min、窒素ガス濃度を0.5%、成長速度を2.3mm/min、偏芯量を12mmとし、さらにP型のドーパントガスであるジボラン(B)を濃度0.01ppmaで含有させたArガスをドープガスノズルから流量5cc/minで溶融帯に吹きつけることにより極微量のガスドープを行なった。
Using this CZ silicon single crystal as a silicon raw material rod, zoning was performed from the low resistance side to the high resistance side by the FZ method to produce a silicon single crystal having a diameter of 205 mm and a straight body length of 90 cm.
In the production of this single crystal, the induction heating coil is a parallel coil having an outer diameter of the inner first heating coil of 220 mm, an outer second heating coil of 300 mm, and a furnace pressure of 0.20 MPa. The Ar gas flow rate is 50 l / min, the nitrogen gas concentration is 0.5%, the growth rate is 2.3 mm / min, the eccentricity is 12 mm, and diborane (B 2 H 6 ), which is a P-type dopant gas, is used. Ar gas contained at a concentration of 0.01 ppma was sprayed from the dope gas nozzle to the melting zone at a flow rate of 5 cc / min to carry out a very small amount of gas dope.

そして、このように製造したシリコン単結晶の抵抗率、酸素濃度、ライフタイムを測定した結果、抵抗率は5000〜10000Ω・cmと元のシリコン原料棒の抵抗率の5倍以上となり、また酸素濃度は0.3ppma、ライフタイムは4000μsecであった。また、この場合の1パス成功率は50%であった。   As a result of measuring the resistivity, oxygen concentration, and lifetime of the silicon single crystal thus produced, the resistivity was 5000 to 10,000 Ω · cm, which is more than five times the resistivity of the original silicon raw material rod, and the oxygen concentration Was 0.3 ppma and the lifetime was 4000 μsec. In this case, the one-pass success rate was 50%.

(比較例1)
直径150mmのシリコン多結晶をシリコン原料棒として、FZ法によりゾーニングを行い、直径205mm、直胴長さ40cmのシリコン単結晶を製造した。
なお、この単結晶の製造の際には、誘導加熱コイルは内側の第一加熱コイルの外径を170mm、外側の第二加熱コイルの外径を280mmのパラレルコイルとし、炉内圧を0.18MPa、Arガス流量を30l/min、窒素ガス濃度を0.3%、成長速度を2.1mm/min、偏芯量を12mmとした。
(Comparative Example 1)
Zoning was performed by FZ method using a silicon polycrystal having a diameter of 150 mm as a silicon raw material rod to produce a silicon single crystal having a diameter of 205 mm and a straight body length of 40 cm.
In the production of the single crystal, the induction heating coil is a parallel coil having an inner first heating coil having an outer diameter of 170 mm and an outer second heating coil having an outer diameter of 280 mm, and the furnace pressure is 0.18 MPa. The Ar gas flow rate was 30 l / min, the nitrogen gas concentration was 0.3%, the growth rate was 2.1 mm / min, and the eccentricity was 12 mm.

そして、このようにシリコン多結晶から製造したシリコン単結晶の抵抗率、酸素濃度、ライフタイムを測定した結果、抵抗率は3000〜8000Ω・cm、酸素濃度は0.3ppma、ライフタイムは6000μsecであった。このときの抵抗率はガスドープをしていないので、シリコン原料棒の抵抗率とほぼ等しいものであった。また、この場合の1パス成功率は10%と低かった。   As a result of measuring the resistivity, oxygen concentration, and lifetime of the silicon single crystal manufactured from the silicon polycrystal in this way, the resistivity was 3000 to 8000 Ω · cm, the oxygen concentration was 0.3 ppma, and the lifetime was 6000 μsec. It was. Since the resistivity at this time was not gas-doped, it was almost equal to the resistivity of the silicon raw material rod. In this case, the one-pass success rate was as low as 10%.

すなわち、実施例のように、本発明に従い抵抗率1000Ω・cm以上のCZシリコン単結晶をシリコン原料棒として、これをFZ法によりゾーニングを行って再結晶化させてシリコン単結晶を製造すれば、直径200mmのような大口径のものでも多結晶シリコンを原料棒とした場合よりも1パス成功率が3倍近く高くなり、本発明の効果が確認された。しかも、原料棒に多結晶を用いる場合、FZ法の原料として使えるような緻密で割れの生じないものは製造が困難であるため、きわめて高価であった。   That is, according to the present invention, a CZ silicon single crystal having a resistivity of 1000 Ω · cm or more is used as a silicon raw material rod according to the present invention, and zoning is performed by the FZ method to recrystallize the silicon single crystal. Even with a large diameter such as 200 mm in diameter, the one-pass success rate was nearly three times higher than when polycrystalline silicon was used as the raw material rod, confirming the effect of the present invention. In addition, when a polycrystalline material is used for the raw material rod, a dense and crack-free material that can be used as a raw material for the FZ method is very expensive because it is difficult to manufacture.

なお、本発明は、上記実施形態に限定されるものではない。上記実施形態は単なる例示であり、本発明の特許請求の範囲に記載された技術的思想と実質的に同一な構成を有し、同様な作用効果を奏するものは、いかなるものであっても本発明の技術的範囲に包含される。   The present invention is not limited to the above embodiment. The above embodiment is merely an example, and the present invention has the same configuration as that of the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

例えば、実施例では直径200mmのシリコン単結晶を製造したが、それ以上の直径のシリコン単結晶を製造する場合は、そのような大口径のシリコン単結晶の製造に適する大口径の多結晶シリコンを高品質で製造するのはより困難かつ高コストであるから、本発明の効果はますます顕著なものとなる。   For example, in the examples, a silicon single crystal having a diameter of 200 mm was manufactured. However, when manufacturing a silicon single crystal having a diameter larger than that, a large-diameter polycrystalline silicon suitable for manufacturing such a large-diameter silicon single crystal was used. The effect of the present invention becomes more pronounced because it is more difficult and expensive to manufacture with high quality.

本発明に係るFZ単結晶製造装置の一例を示す模式的部分断面図である。It is a typical fragmentary sectional view showing an example of the FZ single crystal manufacturing device concerning the present invention.

符号の説明Explanation of symbols

1…FZ単結晶製造装置、 2…シリコン原料棒、 3…シリコン単結晶、
4…上軸、 6…上部保持治具、 8…下軸、 10…下部保持治具、
12…種結晶、 14…誘導加熱コイル、 16…絞り、 18…溶融帯(メルト)、
22…ドープガスノズル。
DESCRIPTION OF SYMBOLS 1 ... FZ single crystal manufacturing apparatus, 2 ... Silicon raw material stick, 3 ... Silicon single crystal,
4 ... Upper shaft, 6 ... Upper holding jig, 8 ... Lower shaft, 10 ... Lower holding jig,
12 ... Seed crystal, 14 ... Induction heating coil, 16 ... Drawing, 18 ... Melt zone,
22 ... Dope gas nozzle.

Claims (5)

FZ法によるシリコン単結晶の製造方法であって、CZ法により製造された、直径が150mm以上であり、抵抗率が1000Ω・cm以上のP型またはN型のシリコン結晶棒をシリコン原料棒として、該シリコン原料棒をFZ法により、直径が200mm以上であり、抵抗率が1000Ω・cm以上のP型またはN型のシリコン単結晶に再結晶化させることを特徴とするシリコン単結晶の製造方法。 A silicon single crystal manufacturing method by the FZ method, wherein a P-type or N-type silicon crystal rod manufactured by the CZ method and having a diameter of 150 mm or more and a resistivity of 1000 Ω · cm or more is used as a silicon raw material rod, A method for producing a silicon single crystal, comprising recrystallizing the silicon raw material rod into a P-type or N-type silicon single crystal having a diameter of 200 mm or more and a resistivity of 1000 Ω · cm or more by an FZ method. 請求項1に記載のシリコン単結晶の製造方法であって、前記再結晶化を行なう際に、前記シリコン原料棒の導電型とは反対の導電型の不純物をガスドープすることにより、前記シリコン原料棒を抵抗率が3000Ω・cm以上のP型またはN型のシリコン単結晶に再結晶化させることを特徴とするシリコン単結晶の製造方法。   2. The method for producing a silicon single crystal according to claim 1, wherein the silicon raw material rod is doped with an impurity having a conductivity type opposite to that of the silicon raw material rod when the recrystallization is performed. Is recrystallized into a P-type or N-type silicon single crystal having a resistivity of 3000 Ω · cm or more. 請求項1または請求項2に記載のシリコン単結晶の製造方法であって、前記シリコン単結晶に含まれる酸素濃度を1ppma(JEIDA)以下とすることを特徴とするシリコン単結晶の製造方法。 3. The method for producing a silicon single crystal according to claim 1 , wherein the concentration of oxygen contained in the silicon single crystal is 1 ppma (JEIDA) or less. 4. 請求項1乃至請求項のいずれか1項に記載のシリコン単結晶の製造方法であって、前記再結晶化を行なう際に、成長炉のチャンバー内雰囲気の窒素濃度を0.2〜0.5%とすることを特徴とするシリコン単結晶の製造方法。 A method for manufacturing a silicon single crystal according to any one of claims 1 to 3, when performing the recrystallization, the nitrogen concentration in the chamber atmosphere in the growth furnace from 0.2 to 0. A method for producing a silicon single crystal, characterized by comprising 5%. 請求項1乃至請求項のいずれか1項に記載のシリコン単結晶の製造方法であって、前記再結晶化を行なう際に、前記シリコン原料棒の低抵抗側から高抵抗側に向かってゾーニングすることにより、前記シリコン原料棒を再結晶化させることを特徴とするシリコン単結晶の製造方法。 A method for manufacturing a silicon single crystal according to any one of claims 1 to 4, when performing the recrystallization, zoning toward the low resistance side of the silicon raw material rod in the high-resistance A method for producing a silicon single crystal, wherein the silicon raw material rod is recrystallized.
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