JP2007070132A - Method for manufacturing single crystal silicon wafer, single crystal silicon wafer, and method for inspecting wafer - Google Patents
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- 238000000034 method Methods 0.000 title claims abstract description 58
- 229910021421 monocrystalline silicon Inorganic materials 0.000 title claims abstract description 39
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 36
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 174
- 239000013078 crystal Substances 0.000 claims abstract description 138
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 86
- 238000010438 heat treatment Methods 0.000 claims abstract description 39
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 30
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 30
- 239000010703 silicon Substances 0.000 claims abstract description 30
- 230000003647 oxidation Effects 0.000 claims abstract description 21
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 21
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 60
- 238000009826 distribution Methods 0.000 claims description 52
- 239000001301 oxygen Substances 0.000 claims description 34
- 229910052760 oxygen Inorganic materials 0.000 claims description 34
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 31
- 229910052786 argon Inorganic materials 0.000 claims description 30
- 239000007789 gas Substances 0.000 claims description 16
- 238000001556 precipitation Methods 0.000 claims description 10
- 238000011156 evaluation Methods 0.000 claims description 8
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 7
- 238000007689 inspection Methods 0.000 claims description 6
- 238000005247 gettering Methods 0.000 abstract description 8
- 230000002093 peripheral effect Effects 0.000 abstract description 5
- 235000012431 wafers Nutrition 0.000 description 117
- 230000000052 comparative effect Effects 0.000 description 21
- 238000000137 annealing Methods 0.000 description 15
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- 239000010410 layer Substances 0.000 description 4
- 150000002926 oxygen Chemical class 0.000 description 4
- 238000005204 segregation Methods 0.000 description 4
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- 239000006104 solid solution Substances 0.000 description 3
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 2
- 229910052581 Si3N4 Inorganic materials 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000002109 crystal growth method Methods 0.000 description 2
- 229910001882 dioxygen Inorganic materials 0.000 description 2
- 125000000896 monocarboxylic acid group Chemical group 0.000 description 2
- 150000002829 nitrogen Chemical class 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
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Abstract
Description
本発明は、半導体デバイスの製造に供される単結晶シリコンウェーハの製造方法、その単結晶シリコンウェーハ、及びそのようなウェーハを製造するためのウェーハ検査方法に関する。 The present invention relates to a method for manufacturing a single crystal silicon wafer used for manufacturing a semiconductor device, the single crystal silicon wafer, and a wafer inspection method for manufacturing such a wafer.
半導体デバイスに用いられるシリコン半導体ウェーハは、主にチョクラルスキー法（ＣＺ法）により引き上げ育成されたシリコン単結晶から製造されている。ＣＺ法は、石英ルツボ内の溶融したシリコンに種結晶を浸けて引き上げ、単結晶を成長させるものである。
ＣＺ法において、石英ルツボから溶融した酸素は結晶中に取り込まれる。この酸素は、凝固直後は十分に固溶しているが、冷却するにつれ固溶度が減少するため、通常、結晶中に過飽和な状態で存在することになる。そしてこの過飽和な酸素は、デバイスの製造工程における熱処理中に酸化物として析出してくる。この酸素析出物あるいはそれに誘起される欠陥は、ＢＭＤ(Bulk Micro Defect) と呼ばれ、デバイス活性領域に存在する場合はデバイス特性を劣化させる要因となるが、基板内部に存在する場合はデバイス製造工程で混入する金属不純物を捕獲するゲッタリング源として有効に作用する。
Silicon semiconductor wafers used for semiconductor devices are mainly manufactured from silicon single crystals that are pulled and grown by the Czochralski method (CZ method). In the CZ method, a seed crystal is immersed in molten silicon in a quartz crucible and pulled to grow a single crystal.
In the CZ method, oxygen melted from a quartz crucible is taken into the crystal. This oxygen is sufficiently dissolved immediately after solidification, but its solid solubility decreases as it cools, so it usually exists in a supersaturated state in the crystal. The supersaturated oxygen is deposited as an oxide during the heat treatment in the device manufacturing process. This oxygen precipitate or a defect induced by the oxygen precipitate is called BMD (Bulk Micro Defect), and if it exists in the device active region, it becomes a factor that degrades the device characteristics. It effectively acts as a gettering source for capturing metal impurities mixed in.
この酸素析出物を有効に活用するために、従来より、ＤＺ−ＩＧ(Denuded Zone-Intrinsic Gettering)処理が行われている。この処理においては、まず、窒素ガス、酸素ガス若しくはこれらの混合ガス雰囲気で、ウェーハに１１５０℃程度で数時間の高温熱処理を施す。これによりウェーハ表層の酸素が外方拡散され、ウェーハ表層に存在する酸素の濃度が低下し、ウェーハ表層に、酸素析出物やそれに誘起される欠陥が存在しないディニューディッド層(Denuded Zone;ＤＺ層) が形成される。その後、さらに５００〜９００℃で数時間の熱処理を施すことで、ウェーハ内部に酸素析出核が形成される。そして、デバイス工程で熱処理を受けることにより酸素析出核が酸素析出物として成長し、ゲッタリング層が形成される。このような処理を行うことにより、ウェーハ表層のデバイス活性領域は無欠陥の一方で、ウェーハ内部には汚染物をデバイス活性領域から除去する吸収層が存在する高品質なウェーハの形成が可能となる。 In order to effectively use this oxygen precipitate, a DZ-IG (Denuded Zone-Intrinsic Gettering) process has been conventionally performed. In this process, first, a high temperature heat treatment is performed on the wafer at about 1150 ° C. for several hours in an atmosphere of nitrogen gas, oxygen gas or a mixed gas thereof. As a result, oxygen on the surface of the wafer is diffused outward, and the concentration of oxygen present on the surface of the wafer is lowered, and a denewed layer (DZ layer) in which oxygen precipitates and defects induced by the oxygen are not present on the surface of the wafer. ) Is formed. Thereafter, heat treatment is further performed at 500 to 900 ° C. for several hours to form oxygen precipitation nuclei inside the wafer. Then, by undergoing heat treatment in the device process, oxygen precipitation nuclei grow as oxygen precipitates, and a gettering layer is formed. By performing such a process, it is possible to form a high-quality wafer in which the device active region on the surface layer of the wafer is defect-free while the wafer has an absorption layer that removes contaminants from the device active region. .
また、ＣＺ法により製造されるシリコン単結晶には、前述した酸素析出物のような熱処理誘起欠陥とは別に、結晶育成時に形成されるＣＯＰ(Crystal Originated Particle)と呼ばれるサイズが０．１μｍ程度のGrown-in 欠陥が１０５ 〜１０６ ｃｍ−３程度存在する。この欠陥は前述した手法では除去することができず、そのままでは半導体デバイスの特性を悪化させる要因となる。
このＣＯＰの密度、サイズを低減させる方法として、水素ガスやアルゴンガス雰囲気で１２００℃程度の高温熱処理を行う方法があり、簡便にウェーハ表層のＣＯＰ密度を低減させることができる方法として知られている。この処理は、前述した酸素外方拡散処理も兼ねており、この手法により得られたシリコンウェーハは、デバイス活性領域であるウェーハ表層に酸素析出物やＣＯＰが不在な高品質ウェーハとなる。
In addition, the silicon single crystal produced by the CZ method has a size called COP (Crystal Originated Particle) formed at the time of crystal growth of about 0.1 μm separately from the heat treatment induced defects such as the oxygen precipitates described above. Grown-in defects are present in the order of 10 5 to 10 6 cm −3 . This defect cannot be removed by the above-described method, and as it is, causes a deterioration in the characteristics of the semiconductor device.
As a method of reducing the density and size of the COP, there is a method of performing a high-temperature heat treatment at about 1200 ° C. in an atmosphere of hydrogen gas or argon gas, which is known as a method that can easily reduce the COP density of the wafer surface layer. . This process also serves as the oxygen out-diffusion process described above, and the silicon wafer obtained by this method becomes a high-quality wafer in which oxygen precipitates and COP are absent on the wafer surface layer, which is a device active region.
この方法によりウェーハ表層域のＣＯＰ密度を効率良く低減するために、結晶育成時に冷却速度を速くすること、又は、結晶育成時に窒素を添加することが提案されている（特許文献１参照）。これによれば、結晶育成中の１１００℃〜８５０℃の温度範囲での冷却中の単結晶の保持時間を８０分未満にすること、あるいは、窒素を少なくとも１×１０１４ atoms／ｃｍ３ 添加することにより、結晶育成時に形成されるＣＯＰの密度は増大するがＣＯＰのサイズを小さくすることができ、熱処理により欠陥が消滅し易くすることができる。 In order to efficiently reduce the COP density in the wafer surface layer region by this method, it has been proposed to increase the cooling rate during crystal growth or to add nitrogen during crystal growth (see Patent Document 1). According to this, the holding time of the single crystal during cooling in the temperature range of 1100 ° C. to 850 ° C. during crystal growth is set to less than 80 minutes, or nitrogen is added at least 1 × 10 14 atoms / cm 3 . As a result, the density of COP formed during crystal growth increases, but the size of COP can be reduced, and defects can be easily eliminated by heat treatment.
ところで、このように結晶育成時に窒素を添加することの利点及び欠点として、高温熱処理でも成長し得る酸素析出核の形成、及び、酸化誘起積層欠陥（Oxidation induced stacking fault;以下、ＯＳＦ）の発生等が報告されている(非特許文献１参照）。酸素析出物のウェーハ面内分布については記載されていないが、ＯＳＦの発生は窒素濃度に強く依存しており、直径２００ｍｍの結晶に対して、窒素を５×１０１４ atoms／ｃｍ３ 添加した場合はＯＳＦの発生領域は外周〜５０ｍｍ程度の範囲までなのに対して、窒素を３×１０１５ atoms／ｃｍ３ 添加した場合はウェーハのほぼ全面にＯＳＦが発生しており、窒素濃度によってウェーハ面内の均一性が異なることを示している。 By the way, the advantages and disadvantages of adding nitrogen at the time of crystal growth as described above include formation of oxygen precipitation nuclei that can grow even at high temperature heat treatment, generation of oxidation induced stacking faults (hereinafter referred to as OSF), and the like. Has been reported (see Non-Patent Document 1). Although there is no description about the distribution of oxygen precipitates in the wafer plane, the generation of OSF strongly depends on the nitrogen concentration, and when nitrogen is added at 5 × 10 14 atoms / cm 3 to a crystal having a diameter of 200 mm. In contrast, the OSF generation region extends from the outer periphery to the range of about 50 mm, but when nitrogen is added at 3 × 10 15 atoms / cm 3 , OSF is generated on almost the entire surface of the wafer, and the nitrogen concentration in the wafer surface increases. It shows that the uniformity is different.
このＯＳＦの発生核は高温でも安定で、エピタキシャルウェーハの酸素析出を促進させる手段として用いることも提案されている（特許文献２参照）。エピタキシャル成長後も安定な酸素析出核は、当然、水素ガス又はアルゴンガスを含む雰囲気で１２００℃程度の熱処理を行っても存在し得ることが十分に考えられる。従って、ＯＳＦをウェーハ全面に発生させることが可能であれば、ウェーハ全面にわたって安定な酸素析出物を形成させることが可能となるが、その際の窒素濃度は３×１０１５ atoms／ｃｍ３ 程度必要とされる（非特許文献１参照）。 It has been proposed that the OSF nuclei are stable even at high temperatures and used as a means for promoting oxygen precipitation in the epitaxial wafer (see Patent Document 2). It is sufficiently conceivable that stable oxygen precipitation nuclei even after epitaxial growth can exist even if heat treatment at about 1200 ° C. is performed in an atmosphere containing hydrogen gas or argon gas. Therefore, if OSF can be generated on the entire surface of the wafer, stable oxygen precipitates can be formed on the entire surface of the wafer, but the nitrogen concentration at that time needs to be about 3 × 10 15 atoms / cm 3. (See Non-Patent Document 1).
また、ＯＳＦをウェーハ全面に発生させる結晶育成方法も提案されている（特許文献３参照）。この方法は、育成された結晶の最大外径をＤmax 、最小外径をＤmin とした時、（Ｄmax −Ｄmin ）／Ｄmin ×１００〔％〕で表される結晶変形率が１．５〜２．０％となる速度を最大引き上げ速度とし、この最大引き上げ速度の０．４〜０．８倍の引き上げ速度で育成する方法である。この方法によれば、窒素濃度が１×１０１２ atoms／ｃｍ３ でＯＳＦ発生領域の拡張が現れてきて、１×１０１４ atoms/ｃｍ３ 以上で望ましいとされている
しかしながら、前述したＯＳＦをウェーハ全面に発生させる結晶育成方法においては、実際にウェーハ全面にＯＳＦが発生した窒素濃度については明記されておらず、通常の引き上げ速度と比較して窒素濃度の低減化が図られたに過ぎず、非特許文献１に開示されている方法と比較して窒素濃度が低減したか否かについては定かでない。
また、この方法では、結晶成長速度を故意に低下させているために、窒素を添加せずに結晶成長を行った場合、ＯＳＦリング領域が結晶面内に出現してしまい、このＯＳＦリング領域を境に内外領域で結晶欠陥の種類が異なることになる。このことは、酸素析出物形成挙動がウェーハ面内で異なることを意味する。
However, in the crystal growth method for generating the OSF on the entire surface of the wafer, the nitrogen concentration at which the OSF is actually generated on the entire surface of the wafer is not specified, and the nitrogen concentration can be reduced as compared with the normal pulling rate. It is only shown and it is not certain whether the nitrogen concentration has been reduced as compared with the method disclosed in
In this method, since the crystal growth rate is intentionally reduced, when crystal growth is performed without adding nitrogen, the OSF ring region appears in the crystal plane, and this OSF ring region is The types of crystal defects are different between the inner and outer regions. This means that the oxygen precipitate formation behavior is different within the wafer plane.
また、前述した窒素を添加する方法においても、十分な析出均一性を得るのに必要な、ＯＳＦ面内均一性・窒素濃度・結晶面内温度分布などが開示されていない。
従って、前述したような方法により高温で安定なＢＭＤ形成に有効なＯＳＦ発生核をウェーハ全面に形成させるには、窒素濃度を３×１０１５ atoms／ｃｍ３ 程度に設定する必要がある。
In addition, the above-described method of adding nitrogen does not disclose OSF in-plane uniformity, nitrogen concentration, crystal in-plane temperature distribution, etc. necessary for obtaining sufficient precipitation uniformity.
Therefore, in order to form OSF generation nuclei effective for high-temperature stable BMD formation on the entire surface of the wafer by the method as described above, it is necessary to set the nitrogen concentration to about 3 × 10 15 atoms / cm 3 .
また、シリコン融液から窒素を添加する場合、偏析現象によって結晶の長さ方向で窒素濃度が変化してしまい、結晶全域にわたり、同じ窒素濃度で結晶育成を行うことはできない。また、シリコン中の窒素の固溶限界は５×１０１５ atoms／ｃｍ３ 程度であり、結晶トップ部で窒素濃度を３×１０１５ atoms/ｃｍ３ に設定し結晶育成を行うと、窒素を添加しない場合と比較し、育成可能な結晶長が極端に短くなり、生産性が大幅に低下する。 In addition, when nitrogen is added from the silicon melt, the nitrogen concentration changes in the length direction of the crystal due to the segregation phenomenon, and the crystal growth cannot be performed at the same nitrogen concentration over the entire crystal region. Further, the solid solution limit of nitrogen in silicon is about 5 × 10 15 atoms / cm 3 , and when crystal growth is performed with the nitrogen concentration set to 3 × 10 15 atoms / cm 3 at the crystal top, nitrogen is added. Compared with the case where it does not, the crystal length which can be grown becomes extremely short, and productivity falls significantly.
結晶育成時の結晶成長軸方向の温度勾配を制御することにより窒素無添加でも全面ＯＳＦ領域が得られ、この領域を用いればＢＭＤの面内均一化が容易であることも開示されているが（特許文献４参照）、具体的な温度勾配の制御範囲や引き上げ速度範囲は開示されておらず、窒素濃度範囲も１×１０１０〜５×１０１５ atoms/ｃｃと広く、生産性を低下させることなく全面ＯＳＦ領域が得られる範囲は明らかでない。同様に、ＯＳＦとＢＭＤが混在する領域で覆われたウェーハを用いることが提案されているが（特許文献５参照）、やはり生産性を低下させることなく実現する方法は開示されていない。
本発明はこのような課題に鑑みてなされたものであって、その目的は、生産性を低下させること無く、ＢＭＤ密度分布の面内不均一性を解消しウェーハ面内で均一なゲッタリング能を有する単結晶シリコンウェーハを製造する単結晶シリコンウェーハの製造方法、そのような単結晶シリコンウェーハ、及びそのようなウェーハを製造するためのウェーハ検査方法を提供することにある。 The present invention has been made in view of such problems, and its object is to eliminate in-plane non-uniformity of the BMD density distribution without reducing productivity and to obtain a uniform gettering capability in the wafer surface. It is an object of the present invention to provide a method for manufacturing a single crystal silicon wafer, a single crystal silicon wafer, and a wafer inspection method for manufacturing such a wafer.
前記課題を解決するために、本願発明者は結晶育成条件について種々検討を行った。その結果、結晶育成時の結晶成長軸方向の温度勾配を制御することにより、生産性を低下させること無く、１×１０１５ atoms／ｃｍ３ 以下の低窒素濃度であってもウェーハ全面にＯＳＦを発生させる方法を見出した。このＯＳＦ核は、高温で安定な酸素析出核と同様の意味を持ち、水素ガスあるいはアルゴンガス雰囲気中で、１２００℃程度の温度範囲で熱処理を行った後も安定に存在できるものである。 In order to solve the above problems, the present inventor has conducted various studies on crystal growth conditions. As a result, by controlling the temperature gradient in the crystal growth axis direction during crystal growth, OSF is applied to the entire wafer surface even at a low nitrogen concentration of 1 × 10 15 atoms / cm 3 or less without reducing productivity. I found a way to generate it. This OSF nucleus has the same meaning as an oxygen precipitation nucleus that is stable at a high temperature, and can exist stably even after heat treatment in a temperature range of about 1200 ° C. in a hydrogen gas or argon gas atmosphere.
結晶育成工程において、シリコン原料を融かす前に、シリコン窒化膜が形成されたシリコンウェーハを窒素ドープ材として添加し育成した結晶は、偏析現象により結晶全長にわたり窒素濃度が変化する。シリコン結晶中の窒素の固溶限界は５×１０１５ atoms／ｃｍ３ 程度であり、これ以上の濃度ではもはや単結晶として結晶を育成することができない。
窒素の偏析係数から算出した結晶中の窒素濃度とＯＳＦ密度は正の相関を持ち、窒素濃度が１×１０１４ atoms／ｃｍ３ を越えるとＯＳＦがウェーハ外周部から高密度に発生し、窒素濃度の増加に伴いその発生領域はウェーハ内部へと広がり、窒素濃度が２．６×１０１５ atoms／ｃｍ３ でウェーハ全面に均一に発生した。
In the crystal growth step, before the silicon raw material is melted, a crystal grown by adding a silicon wafer on which a silicon nitride film is formed as a nitrogen dope changes the nitrogen concentration over the entire length of the crystal due to a segregation phenomenon. The solid solution limit of nitrogen in the silicon crystal is about 5 × 10 15 atoms / cm 3 , and at a concentration higher than this, the crystal can no longer be grown as a single crystal.
The nitrogen concentration in the crystal calculated from the segregation coefficient of nitrogen and the OSF density have a positive correlation. When the nitrogen concentration exceeds 1 × 10 14 atoms / cm 3 , OSF is generated at a high density from the outer periphery of the wafer. With the increase in the area, the generation region spread into the wafer, and the nitrogen concentration was 2.6 × 10 15 atoms / cm 3 and was uniformly generated on the entire surface of the wafer.
これらの隣り合った結晶部位からウェーハを抜き取り、アルゴンガス雰囲気中で１２００℃で１時間の熱処理を行った後、乾燥酸素ガス雰囲気中で１０００℃で１６時間のＢＭＤ成長熱処理を行い、エッチングを施し、ＢＭＤを顕在化させ面内の密度分布を調べたところ、窒素濃度が２．６×１０１５ atoms／ｃｍ３ の部位のみＢＭＤ密度が面内で均一になっていた。その他の結晶部位では、すなわち窒素濃度が１×１０１５ atoms／ｃｍ３ 以下では、結晶外周部で密度低下若しくは密度増加が起こり、不均一なＯＳＦ分布に依存していた。
従って、ＯＳＦをウェーハ全面に均一に発生することが可能なウェーハは、１２００℃程度の高温で熱処理を行った後もＢＭＤがウェーハ面内に均一に形成され、面内で均一なゲッタリング能を持つ優れたウェーハとなる。
The wafer is extracted from these adjacent crystal parts, heat-treated at 1200 ° C. for 1 hour in an argon gas atmosphere, and then subjected to BMD growth heat treatment at 1000 ° C. for 16 hours in a dry oxygen gas atmosphere to perform etching. As a result of revealing the BMD and examining the in-plane density distribution, the BMD density was uniform in the plane only at the site where the nitrogen concentration was 2.6 × 10 15 atoms / cm 3 . At other crystal parts, that is, when the nitrogen concentration is 1 × 10 15 atoms / cm 3 or less, density decrease or density increase occurs at the outer periphery of the crystal and depends on non-uniform OSF distribution.
Therefore, in a wafer that can generate OSF uniformly over the entire surface of the wafer, even after heat treatment at a high temperature of about 1200 ° C., BMD is uniformly formed in the wafer surface, and uniform gettering ability is achieved in the surface. It has an excellent wafer.
このことから、さらに鋭意検討を行った結果、結晶育成中の１３７０℃から１３１０℃間の結晶成長軸方向の温度勾配値が結晶中心部をＧｃ、結晶外周部をＧｅとした時、Ｇｃ／Ｇｅ＝１．２３になるように設計された結晶育成炉の場合、窒素をドープしなくてもウェーハ面内のほぼ全面にＯＳＦを発生させることが可能であることを見出した。そして、このようなＧｃ／Ｇｅの最適化によって、僅かな窒素濃度でＯＳＦをウェーハ全面に発生させることが可能になることを見出した。 From this, as a result of further intensive studies, when the temperature gradient value in the crystal growth axis direction between 1370 ° C. and 1310 ° C. during crystal growth is Gc in the center of the crystal and Ge is in the outer periphery of the crystal, Gc / Ge In the case of a crystal growth furnace designed so that = 1.23, it has been found that OSF can be generated on almost the entire surface of the wafer without doping nitrogen. Then, it was found that such optimization of Gc / Ge makes it possible to generate OSF on the entire wafer surface with a slight nitrogen concentration.
すなわち本発明に係る単結晶シリコンウェーハの製造方法は、チョクラルスキー法によりシリコン単結晶を引き上げ育成する工程を有するシリコン単結晶ウェーハの製造方法であって、高温酸化熱処理を施した場合に酸化誘起積層欠陥がウェーハ全面に発生するように、結晶育成中の温度が１３７０℃〜１３１０℃の時の結晶成長軸方向の温度勾配値の比Ｇｃ／Ｇｅ（但し、Ｇｃ：結晶中心部の平均温度勾配、Ｇｅ：結晶外周部の平均温度勾配）、及び、窒素濃度に応じた引き上げ速度で引き上げ育成を行うことを特徴とする。 In other words, the method for producing a single crystal silicon wafer according to the present invention is a method for producing a silicon single crystal wafer having a step of pulling and growing a silicon single crystal by the Czochralski method, and inducing oxidation when a high temperature oxidation heat treatment is performed. Ratio Gc / Ge of temperature gradient values in the crystal growth axis direction when the temperature during crystal growth is 1370 ° C. to 1310 ° C. (where Gc is the average temperature gradient in the center of the crystal so that stacking faults occur on the entire wafer surface) , Ge: average temperature gradient of the outer periphery of the crystal) and pulling growth at a pulling rate according to the nitrogen concentration.
また、本発明に係る単結晶シリコンウェーハの製造方法は、チョクラルスキー法によりシリコン単結晶を引き上げ育成する工程を有するシリコン単結晶ウェーハの製造方法であって、インゴットの引き上げ方向における直胴部の全長の３０〜７０％の範囲の引き上げ育成を行う際に、結晶育成中の温度が１３７０℃〜１３１０℃であって、結晶成長軸方向の温度勾配値の比Ｇｃ／Ｇｅ（但し、Ｇｃ：結晶中心部の平均温度勾配、Ｇｅ：結晶外周部の平均温度勾配）を１．１４以上１．２８以下の範囲とし、窒素を０．８×１０１４ atoms／ｃｍ３ 以上５×１０１５ atoms／ｃｍ３ 以下の範囲で添加して引き上げ育成を行うことを特徴とする。
Moreover, the method for producing a single crystal silicon wafer according to the present invention is a method for producing a silicon single crystal wafer having a step of pulling and growing a silicon single crystal by the Czochralski method, wherein the straight body portion in the pulling direction of the ingot is When pulling and growing in the range of 30 to 70% of the total length, the temperature during crystal growth is 1370 ° C. to 1310 ° C., and the temperature gradient value ratio Gc / Ge (where Gc: crystal The average temperature gradient at the center, Ge: average temperature gradient at the outer periphery of the crystal) is in the range of 1.14 to 1.28, and nitrogen is 0.8 × 10 14 atoms /
好適には、前記引き上げ育成は、高温酸化熱処理を施した場合に酸化誘起積層欠陥がウェーハ全面に発生するように、窒素濃度に応じた引き上げ速度で行う。
また好適には、前記酸化誘起積層欠陥の密度の最大値と最小値の比（最大値／最小値）が４以下である。
また好適には、水素ガス又はアルゴンガスを含む雰囲気で、１１００℃〜１２５０℃で３０分以上５時間以下の熱処理を施す工程を有する。
Preferably, the pulling growth is performed at a pulling rate according to the nitrogen concentration so that oxidation-induced stacking faults are generated on the entire surface of the wafer when a high temperature oxidation heat treatment is performed.
Preferably, the ratio (maximum value / minimum value) between the maximum value and the minimum value of the density of the oxidation-induced stacking faults is 4 or less.
Preferably, the method includes a step of performing a heat treatment at 1100 ° C. to 1250 ° C. for 30 minutes to 5 hours in an atmosphere containing hydrogen gas or argon gas.
また、本発明に係る単結晶シリコンウェーハは、チョクラルスキー法により引き上げ育成されて製造されるシリコン単結晶ウェーハであって、高温酸化熱処理を施した場合に酸化誘起積層欠陥がウェーハ全面に発生するように、結晶育成中の温度が１３７０℃〜１３１０℃の時の結晶成長軸方向の温度勾配値の比Ｇｃ／Ｇｅ（但し、Ｇｃ：結晶中心部の平均温度勾配、Ｇｅ：結晶外周部の平均温度勾配）、及び、窒素濃度に応じた引き上げ速度で引き上げ育成されたことを特徴とする。 In addition, the single crystal silicon wafer according to the present invention is a silicon single crystal wafer manufactured by pulling and growing by the Czochralski method, and oxidation-induced stacking faults are generated on the entire surface of the wafer when subjected to high temperature oxidation heat treatment. Thus, the ratio Gc / Ge of temperature gradient values in the crystal growth axis direction when the temperature during crystal growth is 1370 ° C. to 1310 ° C. (where Gc is the average temperature gradient of the crystal center, Ge is the average of the crystal periphery) It is characterized by being raised and grown at a pulling rate according to the temperature gradient) and the nitrogen concentration.
また、本発明に係る単結晶シリコンウェーハは、チョクラルスキー法により引き上げ育成されて製造されるシリコン単結晶ウェーハであって、インゴットの引き上げ方向における直胴部の全長の３０〜７０％の範囲の引き上げ育成を行う際に、結晶育成中の温度が１３７０℃〜１３１０℃であって、結晶成長軸方向の温度勾配値の比Ｇｃ／Ｇｅ（但し、Ｇｃ：結晶中心部の平均温度勾配、Ｇｅ：結晶外周部の平均温度勾配）を１．１４以上１．２８以下の範囲とし、窒素を０．８×１０１４ atoms／ｃｍ３ 以上５×１０１５ atoms／ｃｍ３ 以下の範囲で添加して引き上げ育成されたことを特徴とする。
Moreover, the single crystal silicon wafer according to the present invention is a silicon single crystal wafer that is manufactured by being pulled and grown by the Czochralski method, and is in the range of 30 to 70% of the total length of the straight body portion in the pulling direction of the ingot. When pulling growth is performed, the temperature during crystal growth is 1370 ° C. to 1310 ° C., and the temperature gradient value ratio Gc / Ge in the crystal growth axis direction (where Gc is the average temperature gradient at the center of the crystal, Ge: The average temperature gradient at the outer periphery of the crystal is in the range of 1.14 to 1.28, and nitrogen is added in the range of 0.8 × 10 14 atoms /
好適には、酸素析出評価熱処理を施した時に形成されるウェーハ面内の平均ＢＭＤ密度が、１×１０４ 個／ｃｍ２ 以上５×１０６ 個／ｃｍ２ 以下、ウェーハ径方向におけるＢＭＤの密度の最大値／最小値の比が３以下である。
また好適には、酸化誘起積層欠陥のウェーハ面内密度の最大値と最小値の比（最大値／最小値）が４以下である。
また好適には、水素ガス又はアルゴンガスを含む雰囲気で、１１００℃〜１２５０℃で３０分以上５時間以下の熱処理が施されて製造される。
Preferably, the average BMD density in the wafer surface formed when the oxygen precipitation evaluation heat treatment is performed is 1 × 10 4 pieces / cm 2 or more and 5 × 10 6 pieces / cm 2 or less, and the BMD density in the wafer radial direction The ratio of the maximum value / minimum value is 3 or less.
Preferably, the ratio (maximum value / minimum value) of the maximum value and the minimum value of the density in the wafer plane of the oxidation-induced stacking fault is 4 or less.
In addition, it is preferably manufactured by performing a heat treatment at 1100 ° C. to 1250 ° C. for 30 minutes to 5 hours in an atmosphere containing hydrogen gas or argon gas.
また、本発明に係るウェーハ検査方法は、チョクラルスキー法により引き上げ育成され高温酸化熱処理を施して製造されるシリコン単結晶ウェーハのＢＭＤ分布の良否を検査する方法であって、酸化誘起積層欠陥のウェーハ面内密度の分布を測定し、予め求められたＢＭＤ分布とＯＳＦ分布との関係により決定された良否範囲に前記測定されたＯＳＦ分布が属するか否かを判定し、その良否をＢＭＤ分布の良否と推定することを特徴とする。 The wafer inspection method according to the present invention is a method for inspecting the quality of the BMD distribution of a silicon single crystal wafer manufactured by pulling up and growing by the Czochralski method and performing a high temperature oxidation heat treatment. The wafer in-plane density distribution is measured, it is determined whether or not the measured OSF distribution belongs to the quality range determined by the relationship between the BMD distribution and the OSF distribution obtained in advance, and the quality is determined as the BMD distribution. It is characterized by estimating whether it is good or bad.
本発明によれば、生産性を低下させること無く、ＢＭＤ密度分布の面内不均一性を解消しウェーハ面内で均一なゲッタリング能を有する単結晶シリコンウェーハを製造する単結晶シリコンウェーハの製造方法、そのような単結晶シリコンウェーハ、及びそのようなウェーハを製造するためのウェーハ検査方法を提供することができる。 According to the present invention, the manufacture of a single crystal silicon wafer that manufactures a single crystal silicon wafer having a uniform gettering ability in the wafer surface by eliminating in-plane non-uniformity of the BMD density distribution without reducing productivity. Methods, such single crystal silicon wafers, and wafer inspection methods for manufacturing such wafers can be provided.
本発明の実施形態について、図１〜図１０を参照して説明する。
ここでは、２つの比較例及び３つの本発明に係る方法としての実施例について、シリコン単結晶の引き上げ育成を含む単結晶シリコンウェーハの製造条件及び製造方法について説明するとともにＯＳＦ密度及びＢＭＤ密度について評価結果を示し、本発明に係る単結晶シリコンウェーハ、その製造方法及び検査方法の実施形態について説明する。
An embodiment of the present invention will be described with reference to FIGS.
Here, two comparative examples and three examples of the method according to the present invention will be described with respect to the manufacturing conditions and manufacturing method of a single crystal silicon wafer including pulling growth of a silicon single crystal, and evaluated for OSF density and BMD density. A result is shown and embodiment of the single crystal silicon wafer which concerns on this invention, its manufacturing method, and an inspection method is described.
まず最初に、各例に共通的に適用するＯＳＦ密度及びＢＭＤ密度の評価方法について説明する。
各比較例及び実施例の条件に従って育成された結晶からウェーハを切り出した後、窒素ガス雰囲気で６５０℃で３０分の酸素ドナー消去熱処理を施し、そのウェーハに対して各々次のような方法によりウェーハ面内のＯＳＦ密度及び、ＢＭＤ密度の評価を行う。
First, an OSF density and BMD density evaluation method commonly applied to each example will be described.
After the wafer was cut out from the crystal grown according to the conditions of each comparative example and example, an oxygen donor erasing heat treatment was performed at 650 ° C. for 30 minutes in a nitrogen gas atmosphere. In-plane OSF density and BMD density are evaluated.
ＯＳＦ密度評価方法
（１）水蒸気雰囲気中で１１４０℃で２時間の熱処理。
（２）ウェーハ表面に形成された酸化膜をＨＦ：Ｈ２Ｏ ＝１：１の液で除去。
（３）ＨＦ：ＨＮＯ３ ：ＣｒＯ３ ：Ｃｕ（ＮＯ３)２ ：Ｈ２ Ｏ：ＣＨ３ ＣＯＯＨ＝１２００ｃｃ：６００ｃｃ：２５０ｇ：４０ｇ：１７００ｃｃ：１２００ｃｃの液でウェーハ表面を２μｍ除去（これにより欠陥が顕在化）。
（４）光学顕微鏡でウェーハ径方向に５ｍｍあるいは１０ｍｍピッチでＯＳＦ密度を測定。
OSF density evaluation method (1) Heat treatment at 1140 ° C. for 2 hours in a steam atmosphere.
(2) The oxide film formed on the wafer surface is removed with a solution of HF: H2O = 1: 1.
(3) HF: HNO 3: CrO 3: Cu (NO 3) 2: H 2 O:
(4) The OSF density is measured with an optical microscope at a 5 mm or 10 mm pitch in the wafer radial direction.
ＢＭＤ密度評価方法
（１）乾燥酸素雰囲気で１０００℃で１６時間の熱処理。
（２）ウェーハ表面に形成された酸化膜をＨＦ：Ｈ２Ｏ ＝１：１の液で除去。
（３）ウェーハを半分に劈開。
（４）ＨＦ：ＨＮＯ３ ：ＣｒＯ３ ：Ｃｕ（ＮＯ３)２ ：Ｈ２ Ｏ：ＣＨ３ ＣＯＯＨ＝１２００ｃｃ：６００ｃｃ：２５０ｇ：４０ｇ：１７００ｃｃ：１２００ｃｃの液で劈開面を２μｍ除去（これにより欠陥が顕在化）。
（５）光学顕微鏡でウェーハ径方向に５ｍｍあるいは１０ｍｍピッチでエッチピット密度を測定。
BMD density evaluation method (1) Heat treatment at 1000 ° C. for 16 hours in a dry oxygen atmosphere.
(2) The oxide film formed on the wafer surface is removed with a solution of HF: H2O = 1: 1.
(3) Cleave the wafer in half.
(4) HF: HNO 3: CrO 3: Cu (NO 3) 2: H 2 O:
(5) The etch pit density is measured at a pitch of 5 mm or 10 mm in the wafer radial direction with an optical microscope.
以下、比較例１及び比較例２、及び、実施例１〜実施例３について、単結晶シリコンウェーハの製造方法とその評価結果を示す。 Hereinafter, the manufacturing method of a single crystal silicon wafer and its evaluation result are shown about the comparative example 1 and the comparative example 2, and Examples 1-3.
比較例１
比較例１として、少なくともインゴットの引き上げ方向における全長の３０〜７０％の範囲の直胴部の引き上げを、結晶育成中の温度が１３７０℃〜１３１０℃であって、結晶面内の温度勾配比Ｇｃ／Ｇｅが１．００である結晶育成条件にて、８インチｐ型、抵抗率約１０Ωｃｍ、酸素濃度約１２×１０１７ atoms／ｃｍ３ の窒素ドープ結晶の育成を行った。窒素ドープ法としては、結晶育成工程のシリコン原料を融かす工程前にシリコン窒化膜が形成されたシリコンウェーハを窒素ドープ材としてシリコン原料と一緒に仕込んだ。幅広い窒素濃度範囲の結晶を得るため、窒素ドープ材の仕込み量を変えた。結晶中の窒素濃度は、窒素の偏析係数から算出し、０．０１〜４×１０１５ atoms／ｃｍ３ である。なお、引き上げの際に添加する窒素濃度については、インゴット全長の３０〜７０％のみならず、直胴部の全域について、設定された濃度を維持するものとする。
結晶育成後、窒素ガス雰囲気で６５０℃で３０分の酸素ドナー消去熱処理を施したウェーハに加工し、前述したような方法により、ウェーハ面内のＯＳＦ密度及び、ＢＭＤ密度の評価を行った。
Comparative Example 1
As Comparative Example 1, the temperature of the straight body in the range of 30 to 70% of the total length in the pulling direction of the ingot is at a temperature during crystal growth of 1370 ° C to 1310 ° C, and the temperature gradient ratio Gc in the crystal plane Under the crystal growth condition where / Ge is 1.00, an 8-inch p-type, a resistivity of about 10 Ωcm, and an oxygen concentration of about 12 × 10 17 atoms / cm 3 were grown. As the nitrogen doping method, a silicon wafer on which a silicon nitride film was formed was charged together with the silicon raw material as a nitrogen doping material before the step of melting the silicon raw material in the crystal growth step. In order to obtain crystals in a wide range of nitrogen concentration, the amount of nitrogen dope was changed. The nitrogen concentration in the crystal is calculated from the segregation coefficient of nitrogen and is 0.01 to 4 × 10 15 atoms / cm 3 . In addition, about the nitrogen concentration added in the case of pulling up, the set density | concentration shall be maintained not only about 30-70% of the ingot total length but the whole region of a straight body part.
After crystal growth, the wafer was processed into an oxygen donor erasing heat treatment at 650 ° C. for 30 minutes in a nitrogen gas atmosphere, and the OSF density and BMD density in the wafer surface were evaluated by the method described above.
図１に、アルゴンガス雰囲気で熱処理を行う前の比較例１のサンプルのＯＳＦ密度分布を示す。
図１に示すように、この例では、窒素濃度が１．２×１０１３ atoms／ｃｍ３ ではＯＳＦは発生せず、窒素濃度が１．３５×１０１４ atoms／ｃｍ３ で周辺部にＯＳＦが発生し、窒素濃度増加とともにウェーハ外周部から内部に向かってＯＳＦが高密度に発生し、２．６×１０１５ atoms／ｃｍ３ 以上でウェーハ全面に均一に発生している。
FIG. 1 shows the OSF density distribution of the sample of Comparative Example 1 before heat treatment in an argon gas atmosphere.
As shown in FIG. 1, in this example, when the nitrogen concentration is 1.2 × 10 13 atoms / cm 3 , OSF is not generated, and when the nitrogen concentration is 1.35 × 10 14 atoms / cm 3 , OSF is generated in the peripheral portion. As the nitrogen concentration increases, the OSF is generated with a high density from the outer peripheral portion of the wafer toward the inside, and is uniformly generated over the entire wafer at 2.6 × 10 15 atoms / cm 3 or more.
図２に、アルゴンガス雰囲気で熱処理を行う前後の比較例１のサンプルのＢＭＤ密度分布を示す。
図２に示すように、窒素濃度３．６〜５．５×１０１４ atoms／ｃｍ３ でウェーハ外周部から１０〜２０ｍｍの位置でＢＭＤ密度の低下が起こっているが、アルゴンアニール処理前後でＢＭＤ密度分布に差は見られない。また、この窒素濃度範囲でのＯＳＦは、ＢＭＤ密度が低下している位置で高密度に発生している。
窒素濃度が７．８〜９．４×１０１４ atoms／ｃｍ３ と高くなると、ウェーハ外周部においてＢＭＤ密度の低下は起こらず、逆に増加している。また、低窒素濃度の場合と同様に、アルゴンアニール前後でＢＭＤ密度分布に差は見られない。この窒素濃度範囲でのＯＳＦは、ウェーハ中心部近傍まで高密度に発生しているが、その分布は不均一である。
また、窒素濃度が２．６×１０１５ atoms／ｃｍ３ になると、ＢＭＤはウェーハ面内均一に形成され、かつＯＳＦも均一に発生している。また、低窒素濃度の場合と同様に、アルゴンアニール前後でＢＭＤ密度分布に差は見られない。
FIG. 2 shows the BMD density distribution of the sample of Comparative Example 1 before and after heat treatment in an argon gas atmosphere.
As shown in FIG. 2, a decrease in BMD density occurs at a position of 10 to 20 mm from the outer periphery of the wafer at a nitrogen concentration of 3.6 to 5.5 × 10 14 atoms / cm 3. There is no difference in the density distribution. Further, the OSF in this nitrogen concentration range is generated at a high density at a position where the BMD density is lowered.
When the nitrogen concentration increases to 7.8 to 9.4 × 10 14 atoms / cm 3 , the BMD density does not decrease at the outer peripheral portion of the wafer, but increases. In addition, as in the case of the low nitrogen concentration, there is no difference in the BMD density distribution before and after argon annealing. The OSF in this nitrogen concentration range is generated at a high density up to the vicinity of the wafer center, but its distribution is non-uniform.
When the nitrogen concentration is 2.6 × 10 15 atoms / cm 3 , the BMD is uniformly formed in the wafer surface and the OSF is also uniformly generated. In addition, as in the case of the low nitrogen concentration, there is no difference in the BMD density distribution before and after argon annealing.
窒素濃度ごとのアルゴンアニール後のＢＭＤ密度の面内バラツキ（最大値／最小値）を表１に示す。
表１に示すように、アルゴンアニール後のＢＭＤ密度の面内バラツキ（最大値／最小値）は、最大で７倍近くになっている。
Table 1 shows the in-plane variation (maximum value / minimum value) of the BMD density after argon annealing for each nitrogen concentration.
As shown in Table 1, the in-plane variation (maximum value / minimum value) of the BMD density after argon annealing is close to 7 times at maximum.
このような比較例１の評価結果から、ＯＳＦは窒素濃度に依存して結晶外周部から発生すること、及び、ＯＳＦ発生核は高温でも安定で、１２００℃で１時間程度のアルゴンアニール処理では消滅すること無く安定に存在し、アルゴンアニール前後でＢＭＤ密度分布が大きく変わることは無いことが判る。
従って、ＢＭＤ密度を面内均一に形成するためには、ＯＳＦをウェーハ面内均一に発生させるように窒素濃度を制御する必要があり、また、その濃度は、他の条件をこの比較例１と同様にすると、２．６×１０１５ atoms／ｃｍ３ 以上が必要となることになる。
From the evaluation results of Comparative Example 1, OSF is generated from the outer periphery of the crystal depending on the nitrogen concentration, and the OSF generation nuclei are stable even at high temperatures and disappear by argon annealing at 1200 ° C. for about 1 hour. It can be seen that the BMD density distribution does not change significantly before and after argon annealing.
Therefore, in order to form the BMD density uniformly in the surface, it is necessary to control the nitrogen concentration so that the OSF is uniformly generated in the wafer surface. Similarly, 2.6 × 10 15 atoms / cm 3 or more is required.
比較例２
比較例２として、少なくともインゴットの引き上げ方向における全長の３０〜７０％の範囲の直胴部の引き上げを、結晶育成中の温度が１３７０℃〜１３１０℃であって、結晶面内の温度勾配比Ｇｃ／Ｇｅが０．９７である結晶育成条件にて１２インチｐ型、抵抗率約１０Ωｃｍ、酸素濃度約１４×１０１７ atoms／ｃｍ３ の窒素ドープ結晶の育成を行った。窒素ドープ方法は、比較例１と同様の方法により行った。引き上げの際に添加する窒素濃度は直胴部の全域について各々設定された濃度を維持することは比較例１と同様である。
結晶育成後、窒素ガス雰囲気で６５０℃で３０分の酸素ドナー消去熱処理を施したウェーハに加工し、前述したような方法によりウェーハ面内のＯＳＦ密度を評価した。
また、アルゴンガス雰囲気で１２００℃で１時間の熱処理を行ったサンプルウェーハ面内のＢＭＤ密度を、前述したような方法により評価した。
Comparative Example 2
As Comparative Example 2, the temperature of the straight body in the range of 30 to 70% of the total length in the pulling direction of the ingot is at a temperature during crystal growth of 1370 ° C. to 1310 ° C., and the temperature gradient ratio Gc in the crystal plane A nitrogen-doped crystal having a 12-inch p-type, a resistivity of about 10 Ωcm, and an oxygen concentration of about 14 × 10 17 atoms / cm 3 was grown under crystal growth conditions with / Ge of 0.97. The nitrogen doping method was performed in the same manner as in Comparative Example 1. The nitrogen concentration added during the pulling is the same as that in Comparative Example 1 in that the concentration set for the entire area of the straight body portion is maintained.
After crystal growth, the wafer was processed into an oxygen donor erasing heat treatment at 650 ° C. for 30 minutes in a nitrogen gas atmosphere, and the OSF density in the wafer surface was evaluated by the method described above.
Moreover, the BMD density in the sample wafer surface which heat-processed at 1200 degreeC for 1 hour in argon gas atmosphere was evaluated by the method as mentioned above.
図３に、アルゴンガス雰囲気で熱処理を行う前のサンプルのＯＳＦ密度分布を示す。ウェーハ外周部から内部に向かって高密度に発生するも、その分布は不均一であった。
図４に、アルゴンガス雰囲気で熱処理を行う前後のサンプルのＢＭＤ密度分布を示す。面内分布はＯＳＦ密度分布の不均一を反映して、不均一であった。
アルゴンアニール後のＢＭＤ密度の面内ばらつき（最大値／最小値）を表２に示す。表２に示すように、アルゴンアニール後のＢＭＤ密度の面内ばらつき（最大値／最小値）は、最大で１６倍になっている。
FIG. 3 shows the OSF density distribution of the sample before heat treatment in an argon gas atmosphere. Although it occurs at a high density from the outer periphery of the wafer toward the inside, the distribution is non-uniform.
FIG. 4 shows the BMD density distribution of the sample before and after heat treatment in an argon gas atmosphere. The in-plane distribution was non-uniform, reflecting the non-uniform OSF density distribution.
Table 2 shows the in-plane variation (maximum value / minimum value) of the BMD density after argon annealing. As shown in Table 2, the in-plane variation (maximum value / minimum value) of the BMD density after argon annealing is 16 times at maximum.
実施例１
比較例１として前述したように、結晶面内の温度勾配比Ｇｃ／Ｇｅが１．００である結晶育成条件の場合、ウェーハ面内のＢＭＤ密度分布を均一化させるには、窒素濃度が２．６×１０１５ atoms／ｃｍ３ 以上必要であるが、シリコン結晶中の窒素の固溶限界は、５×１０１５ atoms／ｃｍ３ 程度であり、これ以上の濃度ではもはや単結晶として育成することができない。
そこで、低窒素濃度でもＯＳＦをウェーハ全面に発生させるために、結晶育成中のウェーハ面内の温度勾配分布が比較例と異なる結晶育成条件を用いる。具体的には、本発明に係る実施例１として、結晶中心部の温度勾配Ｇｃと結晶外周部の温度勾配Ｇｅとの比Ｇｃ／Ｇｅが１．２３である条件にて結晶を育成した。
Example 1
As described above as Comparative Example 1, in the case of the crystal growth condition where the temperature gradient ratio Gc / Ge in the crystal plane is 1.00, the nitrogen concentration is 2. in order to make the BMD density distribution in the wafer plane uniform. Although 6 × 10 15 atoms / cm 3 or more is necessary, the solid solution limit of nitrogen in the silicon crystal is about 5 × 10 15 atoms / cm 3 , and it can no longer grow as a single crystal at a concentration higher than this. Can not.
Therefore, in order to generate OSF on the entire wafer surface even at a low nitrogen concentration, a crystal growth condition in which the temperature gradient distribution in the wafer surface during crystal growth is different from that in the comparative example is used. Specifically, as Example 1 according to the present invention, a crystal was grown under the condition that the ratio Gc / Ge between the temperature gradient Gc at the center of the crystal and the temperature gradient Ge at the outer periphery of the crystal was 1.23.
育成された結晶を縦割り加工し、乾燥酸素雰囲気中で８００℃で４時間、その後１０００℃で１６時間の熱処理を行った後、ＸＲＴ写真にて観察した。その結果、ほぼウェーハ全面にＯＳＦ発生可能領域が観察された。
これにより、結晶面内の温度勾配比によっては、窒素をドープすること無くほぼウェーハ全面にＯＳＦを発生させることが可能であり、ウェーハ全面にＯＳＦを発生させるには僅かな窒素ドープ量で可能であることが推測される。
The grown crystal was subjected to vertical cutting, heat-treated in a dry oxygen atmosphere at 800 ° C. for 4 hours, and then at 1000 ° C. for 16 hours, and then observed with an XRT photograph. As a result, an OSF generation possible region was observed on almost the entire wafer surface.
As a result, depending on the temperature gradient ratio in the crystal plane, it is possible to generate OSF almost over the entire surface of the wafer without doping nitrogen, and a small amount of nitrogen doping is possible to generate OSF over the entire surface of the wafer. Presumed to be.
実施例２
実施例２として、少なくともインゴットの引き上げ方向における全長の３０〜７０％の範囲の直胴部の引き上げを、結晶育成中の温度が１３７０℃〜１３１０℃であって、結晶面内の温度勾配比Ｇｃ／Ｇｅ＝１．１０，１．１４，１．２５である結晶条件にて１２インチｐ型、抵抗率約１０Ωｃｍ、酸素濃度約１４×１０１７ atoms／ｃｍ３ の窒素ドープ結晶の育成を行い、ＯＳＦ密度とアルゴンガス雰囲気で１２００℃で１時間の熱処理を行った後のＢＭＤ密度分布を、各々前述したような方法により評価した。
Example 2
As Example 2, the temperature during the crystal growth is 1370 ° C. to 1310 ° C. and the temperature gradient ratio Gc in the crystal plane is at least 30% to 70% of the total length in the pulling direction of the ingot. A nitrogen-doped crystal having a 12-inch p-type, a resistivity of about 10 Ωcm, and an oxygen concentration of about 14 × 10 17 atoms / cm 3 is grown under the crystal conditions of /Ge=1.10, 1.14, 1.25, The OSD density and the BMD density distribution after heat treatment at 1200 ° C. for 1 hour in an argon gas atmosphere were evaluated by the methods described above.
図示をしないが、温度勾配比Ｇｃ／Ｇｅ＝１．１０では、比較例（Ｇｃ／Ｇｅ＝１．００）とほぼ同じで、窒素濃度増加とともにウェーハ外周部からＯＳＦが発生し、約２×１０１５ atoms／ｃｍ３ でウェーハ全面にＯＳＦが発生している。 Although not shown, at a temperature gradient ratio Gc / Ge = 1.10, it is almost the same as the comparative example (Gc / Ge = 1.00), and OSF is generated from the outer periphery of the wafer as the nitrogen concentration increases, and about 2 × 10 OSF is generated on the entire surface of the wafer at 15 atoms / cm 3 .
Ｇｃ／Ｇｅ＝１．１４では、図５に示すように、窒素濃度が０．７９×１０１４ atoms／ｃｍ３ 以上でウェーハ全面にＯＳＦが発生した。すなわち、Ｇｃ／Ｇｅ＝１．１４の場合、窒素を０．８×１０１４ atoms／ｃｍ３ 以上ドープすることによりウェーハ全面均一にＯＳＦを発生させることが可能であり、その面内バラツキ（最大値／最小値の比）は、表３に示すように４倍以下となる。 At Gc / Ge = 1.14, as shown in FIG. 5, OSF was generated on the entire wafer surface when the nitrogen concentration was 0.79 × 10 14 atoms / cm 3 or more. That is, when Gc / Ge = 1.14, it is possible to generate OSF uniformly on the entire wafer surface by doping nitrogen with 0.8 × 10 14 atoms / cm 3 or more. / Minimum value ratio) is 4 times or less as shown in Table 3.
Ｇｃ／Ｇｅ＝１．２５では、図６に示すように、評価を行った窒素濃度２．４６×１０１４ atoms／ｃｍ３ 以上８．４７×１０１４ atoms／ｃｍ３ 以下の範囲のいずれの場合においても、ウェーハ全面にＯＳＦが発生した。また、その面内バラツキ（最大値／最小値の比）は、表３に示すように３倍以下となる。 When Gc / Ge = 1.25, as shown in FIG. 6, any case where the nitrogen concentration in the evaluation range is from 2.46 × 10 14 atoms / cm 3 to 8.47 × 10 14 atoms / cm 3. In FIG. 5, OSF was generated on the entire surface of the wafer. Further, the in-plane variation (maximum value / minimum value ratio) is three times or less as shown in Table 3.
Ｇｃ／Ｇｅ＝１．１４及び１．２５の各場合におけるアルゴンアニール後のＢＭＤ密度分布を図７及び図８に示す。ウェーハ全面にＯＳＦが発生していないＧｃ／Ｇｅ＝１．１４、窒素濃度が０．７４×１０１４ atoms／ｃｍ３ の場合を除いて、いずれの場合も比較例で見られたウェーハ外周部でのＢＭＤ密度の低下や増加は無く、ウェーハ面内のバラツキも、表４に示すように３倍以内である。 The BMD density distribution after argon annealing in each case of Gc / Ge = 1.14 and 1.25 is shown in FIGS. Except for the case where Gc / Ge = 1.14 where the OSF is not generated on the entire wafer surface and the nitrogen concentration is 0.74 × 10 14 atoms / cm 3 , in all cases, the wafer outer peripheral portion seen in the comparative example There is no decrease or increase in the BMD density, and the variation in the wafer surface is within 3 times as shown in Table 4.
実施例３
実施例３として、少なくともインゴットの引き上げ方向における全長の３０〜７０％の範囲の直胴部の引き上げを、結晶育成中の温度が１３７０℃〜１３１０℃であって、結晶面内の温度勾配比Ｇｃ／Ｇｅ＝１．２８である結晶育成条件にて１２インチｐ型、抵抗率約１０Ωｃｍ、酸素濃度約１４×１０１７ atoms／ｃｍ３ の窒素ドープ結晶の育成を行った。そして、ＯＳＦ密度と、アルゴンガス雰囲気で１２００℃で１時間の熱処理を行った後のＢＭＤ密度分布とを評価した。
Example 3
As Example 3, the temperature during the crystal growth is 1370 ° C. to 1310 ° C., and the temperature gradient ratio Gc in the crystal plane is at least 30% to 70% of the total length in the pulling direction of the ingot. A nitrogen-doped crystal having a 12-inch p-type, a resistivity of about 10 Ωcm, and an oxygen concentration of about 14 × 10 17 atoms / cm 3 was grown under the crystal growth conditions of /Ge=1.28. Then, the OSF density and the BMD density distribution after heat treatment at 1200 ° C. for 1 hour in an argon gas atmosphere were evaluated.
ＯＳＦ密度を図９に示す。図９に示すように、評価を行った窒素濃度が０．７０〜１．４８×１０１４ atoms／ｃｍ３ のいずれの場合においてもウェーハ全面にＯＳＦが発生している。また、その面内バラツキ（最大値／最小値の比）は、表５に示すように、窒素濃度が０．７０×１０１４ atoms／ｃｍ３ の場合に５倍近い値となっているが、その他の場合は４倍以下となっている。 The OSF density is shown in FIG. As shown in FIG. 9, OSF is generated on the entire surface of the wafer in any case where the evaluated nitrogen concentration is 0.70 to 1.48 × 10 14 atoms / cm 3 . Further, the in-plane variation (maximum value / minimum value ratio), as shown in Table 5, is a value close to five times when the nitrogen concentration is 0.70 × 10 14 atoms / cm 3 . In other cases, it is 4 times or less.
アルゴンアニール後のＢＭＤ密度分布を図１０に示す。ＯＳＦ密度の面内バラツキが５倍近かった窒素濃度が０．７０×１０１４ atoms／ｃｍ３ の場合は、ウェーハ中心部でのＢＭＤ密度の増加が見られているが、その他の場合はウェーハ外周部でのＢＭＤ密度の低下や増加は無く、ウェーハ面内のばらつきも表６に示すように３倍以内である。 FIG. 10 shows the BMD density distribution after argon annealing. When the in-plane variation of the OSF density is close to 5 times, when the nitrogen concentration is 0.70 × 10 14 atoms / cm 3 , the BMD density is increased at the center of the wafer. There is no decrease or increase in the BMD density at the portion, and the variation in the wafer surface is within 3 times as shown in Table 6.
以上説明したように、少なくともインゴットの引き上げ方向における全長の３０〜７０％の範囲の直胴部の引き上げを、結晶育成中の温度が１３７０℃〜１３１０℃であって、結晶育成中の１３７０℃〜１３１０℃の間の結晶成長軸方向の温度勾配値を、結晶中心部をＧｃ、結晶外周部をＧｅとした時、その比Ｇｃ／Ｇｅが、１．１４≦Ｇｃ／Ｇｅ≦１．２８の結晶育成条件においては、窒素濃度が０．８×１０１４ atoms／ｃｍ３ であっても、ウェーハ全面にＯＳＦを発生することができ、１２００℃程度の高温で熱処理を行った後も、高密度にＢＭＤをウェーハ面内均一に形成することができる。その結果、ウェーハ面内で均一なゲッタリング能を得ることができる。 As described above, at least the straight body portion is lifted in a range of 30 to 70% of the entire length in the pulling direction of the ingot, the temperature during crystal growth is 1370 ° C to 1310 ° C, and 1370 ° C during crystal growth When the temperature gradient value in the crystal growth axis direction between 1310 ° C. is Gc for the center of the crystal and Ge for the outer periphery of the crystal, the ratio Gc / Ge is 1.14 ≦ Gc / Ge ≦ 1.28. Under the growth conditions, even if the nitrogen concentration is 0.8 × 10 14 atoms / cm 3 , OSF can be generated on the entire surface of the wafer, and the density can be increased even after the heat treatment at about 1200 ° C. BMD can be formed uniformly in the wafer surface. As a result, uniform gettering capability can be obtained within the wafer surface.
なお、本実施形態は、本発明の理解を容易にするために記載されたものであって本発明を何ら限定するものではない。本実施形態に開示された各要素は、本発明の技術的範囲に属する全ての設計変更や均等物をも含み、また任意好適な種々の改変が可能である。 In addition, this embodiment is described in order to make an understanding of this invention easy, and does not limit this invention at all. Each element disclosed in the present embodiment includes all design changes and equivalents belonging to the technical scope of the present invention, and various suitable modifications can be made.
Claims (11)
高温酸化熱処理を施した場合に酸化誘起積層欠陥がウェーハ全面に発生するように、結晶育成中の温度が１３７０℃〜１３１０℃の時の結晶成長軸方向の温度勾配値の比Ｇｃ／Ｇｅ（但し、Ｇｃ：結晶中心部の平均温度勾配、Ｇｅ：結晶外周部の平均温度勾配）、及び、窒素濃度に応じた引き上げ速度で引き上げ育成を行うことを特徴とする単結晶シリコンウェーハの製造方法。 A method for producing a silicon single crystal wafer having a step of pulling and growing a silicon single crystal by the Czochralski method,
A ratio Gc / Ge of temperature gradient values in the crystal growth axis direction when the temperature during crystal growth is 1370 ° C. to 1310 ° C. so that oxidation-induced stacking faults occur on the entire surface of the wafer when high-temperature oxidation heat treatment is performed. , Gc: average temperature gradient at the center of the crystal, Ge: average temperature gradient at the outer periphery of the crystal), and a method for producing a single crystal silicon wafer, characterized by performing pulling growth at a pulling rate according to the nitrogen concentration.
インゴットの引き上げ方向における直胴部の全長の３０〜７０％の範囲の引き上げ育成を行う際に、結晶育成中の温度が１３７０℃〜１３１０℃であって、結晶成長軸方向の温度勾配値の比Ｇｃ／Ｇｅ（但し、Ｇｃ：結晶中心部の平均温度勾配、Ｇｅ：結晶外周部の平均温度勾配）を１．１４以上１．２８以下の範囲とし、窒素を０．８×１０１４ atoms／ｃｍ３ 以上５×１０１５ atoms／ｃｍ３ 以下の範囲で添加して引き上げ育成を行うことを特徴とする単結晶シリコンウェーハの製造方法。 A method for producing a silicon single crystal wafer having a step of pulling and growing a silicon single crystal by the Czochralski method,
When pulling and growing in the range of 30 to 70% of the total length of the straight body in the pulling direction of the ingot, the temperature during crystal growth is 1370 ° C to 1310 ° C, and the ratio of temperature gradient values in the crystal growth axis direction Gc / Ge (where Gc: average temperature gradient at the center of the crystal, Ge: average temperature gradient at the outer periphery of the crystal) is in the range of 1.14 to 1.28, and nitrogen is 0.8 × 10 14 atoms / cm A method for producing a single crystal silicon wafer, characterized by performing pulling growth by adding in a range of 3 to 5 × 10 15 atoms / cm 3 .
酸化誘起積層欠陥のウェーハ面内密度の分布を測定し、予め求められたＢＭＤ分布とＯＳＦ分布との関係により決定された良否範囲に前記測定されたＯＳＦ分布が属するか否かを判定し、その良否をＢＭＤ分布の良否と推定することを特徴とするウェーハ検査方法。
It is a method for inspecting the quality of BMD distribution of a silicon single crystal wafer produced by raising and growing by the Czochralski method and performing heat treatment,
Measure the distribution of density of oxidation-induced stacking faults in the wafer surface, determine whether the measured OSF distribution belongs to the pass / fail range determined by the relationship between the BMD distribution and the OSF distribution obtained in advance, A wafer inspection method, wherein quality is estimated as quality of a BMD distribution.
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| JP2010064953A (en) * | 2008-09-10 | 2010-03-25 | Siltronic Ag | Semiconductor wafer composed of monocrystalline silicon and method for producing the same |
| KR20190135913A (en) | 2018-05-29 | 2019-12-09 | 신에쯔 한도타이 가부시키가이샤 | Method for manufacturing silicon single crystal, epitaxial silicon wafer and silicon single crystal substrate |
| CN115404539A (en) * | 2022-08-30 | 2022-11-29 | 西安奕斯伟材料科技有限公司 | Method for pulling single crystal silicon rod by Czochralski method, single crystal silicon rod, silicon wafer and epitaxial silicon wafer |
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| JPH11189493A (en) * | 1997-12-25 | 1999-07-13 | Sumitomo Metal Ind Ltd | Silicon single crystal and epitaxial wafer |
| JP2004304095A (en) * | 2003-04-01 | 2004-10-28 | Sumitomo Mitsubishi Silicon Corp | Silicon wafer, and manufacturing method thereof |
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| JPH11189493A (en) * | 1997-12-25 | 1999-07-13 | Sumitomo Metal Ind Ltd | Silicon single crystal and epitaxial wafer |
| JP2004304095A (en) * | 2003-04-01 | 2004-10-28 | Sumitomo Mitsubishi Silicon Corp | Silicon wafer, and manufacturing method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2010064953A (en) * | 2008-09-10 | 2010-03-25 | Siltronic Ag | Semiconductor wafer composed of monocrystalline silicon and method for producing the same |
| US8398766B2 (en) | 2008-09-10 | 2013-03-19 | Siltronic Ag | Semiconductor wafer composed of monocrystalline silicon and method for producing it |
| KR20190135913A (en) | 2018-05-29 | 2019-12-09 | 신에쯔 한도타이 가부시키가이샤 | Method for manufacturing silicon single crystal, epitaxial silicon wafer and silicon single crystal substrate |
| CN115404539A (en) * | 2022-08-30 | 2022-11-29 | 西安奕斯伟材料科技有限公司 | Method for pulling single crystal silicon rod by Czochralski method, single crystal silicon rod, silicon wafer and epitaxial silicon wafer |
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