JP4218681B2 - Silicon single crystal substrate manufacturing method, resistance characteristic measuring method, and resistance characteristic guarantee method - Google Patents
Silicon single crystal substrate manufacturing method, resistance characteristic measuring method, and resistance characteristic guarantee method Download PDFInfo
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- 229910052710 silicon Inorganic materials 0.000 title claims description 207
- 239000010703 silicon Substances 0.000 title claims description 207
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims description 205
- 239000000758 substrate Substances 0.000 title claims description 186
- 238000000034 method Methods 0.000 title claims description 58
- 238000004519 manufacturing process Methods 0.000 title claims description 55
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 153
- 238000010438 heat treatment Methods 0.000 claims description 119
- 229910052757 nitrogen Inorganic materials 0.000 claims description 74
- 238000009826 distribution Methods 0.000 claims description 52
- 239000012298 atmosphere Substances 0.000 claims description 25
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 24
- 239000001301 oxygen Substances 0.000 claims description 24
- 229910052760 oxygen Inorganic materials 0.000 claims description 24
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 8
- 238000005259 measurement Methods 0.000 claims description 6
- 239000004065 semiconductor Substances 0.000 description 33
- 230000000694 effects Effects 0.000 description 20
- 239000012535 impurity Substances 0.000 description 17
- 230000007547 defect Effects 0.000 description 9
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- QKCGXXHCELUCKW-UHFFFAOYSA-N n-[4-[4-(dinaphthalen-2-ylamino)phenyl]phenyl]-n-naphthalen-2-ylnaphthalen-2-amine Chemical compound C1=CC=CC2=CC(N(C=3C=CC(=CC=3)C=3C=CC(=CC=3)N(C=3C=C4C=CC=CC4=CC=3)C=3C=C4C=CC=CC4=CC=3)C3=CC4=CC=CC=C4C=C3)=CC=C21 QKCGXXHCELUCKW-UHFFFAOYSA-N 0.000 description 1
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- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
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- C30B13/00—Single-crystal growth by zone-melting; Refining by zone-melting
- C30B13/08—Single-crystal growth by zone-melting; Refining by zone-melting adding crystallising materials or reactants forming it in situ to the molten zone
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- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
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Description
本発明は、窒素が添加された高抵抗率のシリコン単結晶基板の製造方法及び抵抗特性測定方法並びに抵抗特性保証方法に関する。 The present invention relates to a method for manufacturing a high resistivity silicon single crystal substrate to which nitrogen is added, a method for measuring resistance characteristics, and a method for guaranteeing resistance characteristics.
従来、シリコン単結晶基板の製造またはこれを使用する半導体素子の製造においては、シリコン単結晶基板は不純物拡散、酸化工程、ゲッタリング処理等を目的として、６００〜１３００℃前後の広範囲の温度範囲で熱処理をその工程中に受ける。 Conventionally, in the manufacture of a silicon single crystal substrate or a semiconductor device using the same, the silicon single crystal substrate has a wide temperature range of about 600 to 1300 ° C. for the purpose of impurity diffusion, oxidation process, gettering treatment, and the like. A heat treatment is applied during the process.
一方、例えば１０００℃以上の高温領域における熱処理の際にシリコン単結晶基板に発生する熱応力による転位発生の抑制、あるいは単結晶育成時における結晶欠陥の発生を防止する目的で、シリコン単結晶育成時に窒素を添加することが知られている。 On the other hand, for the purpose of suppressing the occurrence of dislocation due to thermal stress generated in the silicon single crystal substrate during heat treatment in a high temperature region of, for example, 1000 ° C. or higher, or preventing the generation of crystal defects during single crystal growth, It is known to add nitrogen.
ところが、窒素が添加されたシリコン単結晶基板は、熱処理を施すと、その抵抗率が熱処理前の値から変化することが知られている。このため、このような窒素が添加されたシリコン単結晶基板に、前述のような半導体素子の製造工程中の熱処理を行うと、抵抗率が変化し、製造する半導体素子の特性も変化してしまうという好ましくない問題があった。 However, it is known that when a silicon single crystal substrate to which nitrogen is added is subjected to a heat treatment, its resistivity changes from a value before the heat treatment. Therefore, when the silicon single crystal substrate to which such nitrogen is added is subjected to the heat treatment during the manufacturing process of the semiconductor element as described above, the resistivity changes and the characteristics of the semiconductor element to be manufactured also change. There was an unfavorable problem.
このような問題点に対して、少なくとも半導体素子製造工程前に、シリコン単結晶基板に９００〜１２５０℃の温度で約１０〜６０分の熱処理を行うことにより、半導体素子製造工程で行われる熱処理によっても抵抗率が変化しないシリコン単結晶基板の製造方法が開示されている（特許第２７４２２４７号公報）。 To solve this problem, at least before the semiconductor element manufacturing process, the silicon single crystal substrate is subjected to a heat treatment at a temperature of 900 to 1250 ° C. for about 10 to 60 minutes. A method for manufacturing a silicon single crystal substrate in which the resistivity does not change is disclosed (Japanese Patent No. 2742247).
一方、近年、基板面内での平均抵抗率が１０００Ω・ｃｍを超えるような高抵抗率のシリコン単結晶基板の需要が高まっている。ところが、熱処理前の抵抗率が３０００Ω・ｃｍのＮ型シリコン単結晶基板の場合、熱処理後の抵抗率が９００Ω・ｃｍ以上も変化する場合がある。このような高抵抗率の結晶の育成では、抵抗率の制御が非常に困難なものとなっていた。 On the other hand, in recent years, a demand for a silicon single crystal substrate having a high resistivity such that the average resistivity in the substrate plane exceeds 1000 Ω · cm is increasing. However, in the case of an N-type silicon single crystal substrate having a resistivity before heat treatment of 3000 Ω · cm, the resistivity after heat treatment may change by 900 Ω · cm or more. In growing such a high resistivity crystal, it has been very difficult to control the resistivity.
ここで、シリコン単結晶基板の抵抗率評価の方法の一つとして、一枚の基板面内の抵抗率の分布である面内抵抗率分布を評価する方法がある。面内抵抗率分布を評価する指標として、ＲＲＧ（Ｒａｄｉａｌ Ｒｅｓｉｓｔｉｖｉｔｙ Ｇｒａｄｉｅｎｔ）が主に用いられる。ＲＲＧとは、一枚のシリコン単結晶基板面内の任意の位置で測定した抵抗率測定群の中の最大値と最小値の差を、最小値で除した値を百分率で表したものである。すなわち、抵抗率の最大値をρｍａｘ、最小値をρｍｉｎとすると、ＲＲＧは下記式で表される。 Here, as one of methods for evaluating the resistivity of a silicon single crystal substrate, there is a method of evaluating an in-plane resistivity distribution, which is a resistivity distribution within a single substrate surface. As an index for evaluating the in-plane resistivity distribution, RRG (Radial Resistivity Gradient) is mainly used. RRG is a percentage obtained by dividing the difference between the maximum value and the minimum value in the resistivity measurement group measured at an arbitrary position within the surface of a single silicon single crystal substrate by the minimum value. . That is, when the maximum value of resistivity is ρmax and the minimum value is ρmin, RRG is expressed by the following equation.
この値が小さいほど、シリコン単結晶基板の面内抵抗率分布はより均一であり、半導体素子製造工程において、一枚のシリコン単結晶基板から製造される半導体素子の各々の抵抗率は均一なものとなる。すなわち、ＲＲＧが小さいシリコン単結晶基板である程、均一な抵抗率の半導体素子の収率が高いので好ましい。 The smaller this value is, the more uniform the in-plane resistivity distribution of the silicon single crystal substrate is, and in the semiconductor device manufacturing process, the resistivity of each semiconductor device manufactured from a single silicon single crystal substrate is uniform. It becomes. That is, a silicon single crystal substrate having a small RRG is preferable because a yield of a semiconductor element having a uniform resistivity is high.
本発明は、窒素を添加した、１０００Ω・ｃｍを超えるような高抵抗率のシリコン単結晶基板において、半導体素子製造工程中に熱処理を行っても抵抗率が大きく変化しないシリコン単結晶基板の製造方法、及び、シリコン単結晶基板製品の正確な抵抗特性保証を行うことを可能にするシリコン単結晶基板の抵抗特性測定方法及び抵抗特性保証方法を提供することを目的とする。
尚、ここで抵抗特性とは、抵抗率、面内抵抗率分布等を意味する。The present invention relates to a silicon single crystal substrate having a high resistivity exceeding 1000 Ω · cm to which nitrogen is added, and a method for producing a silicon single crystal substrate in which the resistivity does not change greatly even if heat treatment is performed during a semiconductor element manufacturing process. Another object of the present invention is to provide a method for measuring resistance characteristics of a silicon single crystal substrate and a method for guaranteeing resistance characteristics, which make it possible to ensure accurate resistance characteristics of a silicon single crystal substrate product.
Here, the resistance characteristics mean resistivity, in-plane resistivity distribution, and the like.
上記目的達成のため、本発明は、平均抵抗率が１０００Ω・ｃｍ以上のシリコン単結晶基板を製造する方法であって、少なくとも、フローティングゾーン法（ＦＺ法）により窒素を添加しながらシリコン単結晶インゴットを育成し、該育成したシリコン単結晶インゴットを切断してシリコン単結晶基板を作製し、該作製したシリコン単結晶基板に、９００〜１２５０℃の温度で１０〜１２０分の熱処理を行うことを特徴とするシリコン単結晶基板の製造方法を提供する。 In order to achieve the above object, the present invention provides a method for producing a silicon single crystal substrate having an average resistivity of 1000 Ω · cm or more, and at least a silicon single crystal ingot while adding nitrogen by a floating zone method (FZ method). The grown silicon single crystal ingot is cut to produce a silicon single crystal substrate, and the produced silicon single crystal substrate is subjected to heat treatment at a temperature of 900 to 1250 ° C. for 10 to 120 minutes. A method for manufacturing a silicon single crystal substrate is provided.
このように、高抵抗率のシリコン単結晶基板の作製に適するＦＺ法により窒素を添加しながら育成したシリコン単結晶インゴットを切断して作製した面内の平均抵抗率が１０００Ω・ｃｍ以上のシリコン単結晶基板に、９００〜１２５０℃の温度で１０〜１２０分の熱処理を行えば、添加した窒素のドナーとしての作用を消去し、その後の半導体素子製造工程等での熱処理においても抵抗率が大きく変化しないシリコン単結晶基板を製造することができる。 Thus, a silicon single crystal having an in-plane average resistivity of 1000 Ω · cm or more produced by cutting a silicon single crystal ingot grown while adding nitrogen by the FZ method suitable for the production of a high resistivity silicon single crystal substrate. If the crystal substrate is heat-treated at a temperature of 900 to 1250 ° C. for 10 to 120 minutes, the effect of the added nitrogen as a donor is eliminated, and the resistivity changes greatly even in the heat treatment in the subsequent semiconductor element manufacturing process and the like. It is possible to manufacture a silicon single crystal substrate that does not.
このとき、前記シリコン単結晶インゴットに添加する窒素濃度を３×１０１４ａｔｏｍｓ／ｃｍ３以上とすることが好ましい。
このように育成中にシリコン単結晶インゴットに添加する窒素濃度が３×１０１４ａｔｏｍｓ／ｃｍ３以上であれば、窒素のドナーとしての抵抗率に対する寄与が大きいため、その作用を消去する熱処理を行うことにより抵抗率変化の抑制効果もより高いものとなる。
尚、シリコン単結晶に添加する窒素濃度が５×１０１５ａｔｏｍｓ／ｃｍ３を超えると単結晶化しなくなり、１×１０１５ａｔｏｍｓ／ｃｍ３以下とすることで確実に無転位化した単結晶を育成できる。At this time, the nitrogen concentration added to the silicon single crystal ingot is preferably 3 × 10 14 atoms / cm 3 or more.
Thus, if the nitrogen concentration added to the silicon single crystal ingot during growth is 3 × 10 14 atoms / cm 3 or more, since the contribution to the resistivity as a donor of nitrogen is large, heat treatment for eliminating the effect is performed. As a result, the effect of suppressing the change in resistivity is further increased.
Note that when the concentration of nitrogen added to the silicon single crystal exceeds 5 × 10 15 atoms / cm 3 , the single crystal is no longer crystallized, and a single crystal that is reliably dislocation-free is grown by setting it to 1 × 10 15 atoms / cm 3 or less. it can.
また、前記シリコン単結晶基板に行う熱処理を、ウェット酸素雰囲気、ドライ酸素雰囲気、窒素雰囲気のいずれか１つの雰囲気下で行うことが好ましい。
このように、前記熱処理をウェット酸素雰囲気、ドライ酸素雰囲気、窒素雰囲気のいずれか１つの雰囲気下で行うことにより、窒素のドナーとしての作用の消去を効果的に行うことができる。The heat treatment performed on the silicon single crystal substrate is preferably performed in one of a wet oxygen atmosphere, a dry oxygen atmosphere, and a nitrogen atmosphere.
In this way, by performing the heat treatment in any one of a wet oxygen atmosphere, a dry oxygen atmosphere, and a nitrogen atmosphere, the action of nitrogen as a donor can be effectively eliminated.
また、本発明は、フローティングゾーン法（ＦＺ法）により育成されたシリコン単結晶インゴットから作製した面内の平均抵抗率が１０００Ω・ｃｍ以上のシリコン単結晶基板の抵抗特性を測定する方法であって、窒素を添加しながらシリコン単結晶インゴットを育成し、該育成したシリコン単結晶インゴットを切断してシリコン単結晶基板を作製し、該作製したシリコン単結晶基板に、９００〜１２５０℃の温度で１０〜１２０分の熱処理を行った後、前記作製したシリコン単結晶基板の抵抗率及び／又は面内抵抗率分布を測定することを特徴とするシリコン単結晶基板の抵抗特性測定方法を提供する。 The present invention is also a method for measuring the resistance characteristics of a silicon single crystal substrate having an in-plane average resistivity of 1000 Ω · cm or more produced from a silicon single crystal ingot grown by the floating zone method (FZ method). Then, a silicon single crystal ingot is grown while adding nitrogen, the grown silicon single crystal ingot is cut to produce a silicon single crystal substrate, and the produced silicon single crystal substrate is heated at a temperature of 900 to 1250 ° C. Provided is a method for measuring resistance characteristics of a silicon single crystal substrate, characterized by measuring the resistivity and / or in-plane resistivity distribution of the produced silicon single crystal substrate after heat treatment for ˜120 minutes.
このように、高抵抗率のシリコン単結晶基板の作製に適するＦＺ法により窒素を添加しながら育成したシリコン単結晶インゴットを切断して作製した面内の平均抵抗率が１０００Ω・ｃｍ以上のシリコン単結晶基板に、９００〜１２５０℃の温度で１０〜１２０分の熱処理を行った後、前記作製したシリコン単結晶基板の抵抗率及び／又は面内抵抗率分布を測定すれば、添加した窒素のドナーとしての作用が消去された後の抵抗特性（抵抗率及び／又は面内抵抗率分布）を測定することとなる。従って１０００Ω・ｃｍ以上のような高抵抗率のシリコン単結晶基板であっても、抵抗特性はその後の半導体素子製造工程等での熱処理においても前記測定した抵抗特性から大きく変化しないので、シリコン単結晶基板製造において正確な抵抗特性保証が可能になる。 Thus, a silicon single crystal having an in-plane average resistivity of 1000 Ω · cm or more produced by cutting a silicon single crystal ingot grown while adding nitrogen by the FZ method suitable for the production of a high resistivity silicon single crystal substrate. If the resistivity and / or in-plane resistivity distribution of the produced silicon single crystal substrate is measured after performing heat treatment on the crystal substrate at a temperature of 900 to 1250 ° C. for 10 to 120 minutes, the added nitrogen donor Then, the resistance characteristic (resistivity and / or in-plane resistivity distribution) after the action of the above is eliminated is measured. Therefore, even in the case of a silicon single crystal substrate having a high resistivity such as 1000 Ω · cm or more, the resistance characteristics do not change greatly from the measured resistance characteristics even in the subsequent heat treatment in the semiconductor device manufacturing process or the like. It is possible to guarantee an accurate resistance characteristic in the manufacture of the substrate.
このとき、前記シリコン単結晶インゴットに添加する窒素濃度を３×１０１４ａｔｏｍｓ／ｃｍ３以上とすることが好ましい。
このように育成中にシリコン単結晶インゴットに添加する窒素濃度が３×１０１４ａｔｏｍｓ／ｃｍ３以上であれば、欠陥等の発生防止効果が高いとともに、窒素のドナーとしての抵抗特性に対する寄与が大きいため、その作用を消去する熱処理を行うことにより抵抗特性変化の抑制効果もより高いものとなり、本発明に従う抵抗特性測定方法によってより正確な抵抗特性の保証が可能となる。At this time, the nitrogen concentration added to the silicon single crystal ingot is preferably 3 × 10 14 atoms / cm 3 or more.
Thus, if the concentration of nitrogen added to the silicon single crystal ingot during growth is 3 × 10 14 atoms / cm 3 or more, the effect of preventing the occurrence of defects and the like is high, and the contribution to the resistance characteristics of nitrogen as a donor is large. Therefore, by performing the heat treatment for eliminating the action, the effect of suppressing the change in the resistance characteristic is further enhanced, and the resistance characteristic measurement method according to the present invention can guarantee the resistance characteristic more accurately.
また、前記シリコン単結晶基板に行う熱処理を、ウェット酸素雰囲気、ドライ酸素雰囲気、窒素雰囲気のいずれか１つの雰囲気下で行うことが好ましい。
このように、前記熱処理をウェット酸素雰囲気、ドライ酸素雰囲気、窒素雰囲気のいずれか１つの雰囲気下で行うことにより、窒素のドナーとしての作用の消去を効果的に行うことができるので、その後より正確かつ迅速に抵抗特性を測定することができる。The heat treatment performed on the silicon single crystal substrate is preferably performed in one of a wet oxygen atmosphere, a dry oxygen atmosphere, and a nitrogen atmosphere.
In this way, by performing the heat treatment in any one of a wet oxygen atmosphere, a dry oxygen atmosphere, and a nitrogen atmosphere, it is possible to effectively eliminate the action of the nitrogen as a donor. In addition, the resistance characteristic can be measured quickly.
また、本発明は、前記いずれかのシリコン単結晶基板の抵抗特性測定方法により測定された測定値を前記作製したシリコン単結晶基板の抵抗率及び／又は面内抵抗率分布の保証値として用いることを特徴とするシリコン単結晶基板の抵抗特性保証方法を提供する。 Further, in the present invention, the measured value measured by any one of the above-described methods for measuring the resistance characteristic of a silicon single crystal substrate is used as a guaranteed value of the resistivity and / or in-plane resistivity distribution of the manufactured silicon single crystal substrate. A method for guaranteeing resistance characteristics of a silicon single crystal substrate is provided.
このように、前記の抵抗特性測定方法によって測定されたシリコン単結晶基板の抵抗特性は、半導体素子製造工程等でシリコン単結晶基板に熱処理が施されても変化しない値であるので、これをシリコン単結晶基板製品の保証値として用いることは信頼度の高い抵抗特性の保証方法となる。 As described above, the resistance characteristic of the silicon single crystal substrate measured by the above-described resistance characteristic measurement method is a value that does not change even when the silicon single crystal substrate is subjected to a heat treatment in a semiconductor element manufacturing process or the like. Using it as a guaranteed value for a single crystal substrate product provides a reliable method for guaranteeing resistance characteristics.
本発明に従い、平均抵抗率が１０００Ω・ｃｍ以上のシリコン単結晶基板を製造する際に、少なくとも、フローティングゾーン法（ＦＺ法）により窒素を添加しながらシリコン単結晶インゴットを育成し、該育成したシリコン単結晶インゴットを切断してシリコン単結晶基板を作製し、該作製したシリコン単結晶基板に、９００〜１２５０℃の温度で１０〜１２０分の熱処理を行えば、転位や結晶欠陥の発生の抑制のために添加した窒素のドナーとしての作用の消去をあらかじめ行うことができるので、その後にシリコン単結晶基板が半導体素子製造工程等で様々な熱処理を受けても、平均抵抗率が１０００Ω・ｃｍ以上の場合に発生するシリコン単結晶基板の抵抗率の大きな変化を抑制することができる。 According to the present invention, when producing a silicon single crystal substrate having an average resistivity of 1000 Ω · cm or more, a silicon single crystal ingot is grown at least while adding nitrogen by the floating zone method (FZ method), and the grown silicon A single crystal ingot is cut to produce a silicon single crystal substrate, and the produced silicon single crystal substrate is subjected to a heat treatment at a temperature of 900 to 1250 ° C. for 10 to 120 minutes, thereby suppressing the occurrence of dislocations and crystal defects. Therefore, even if the silicon single crystal substrate is subjected to various heat treatments in the semiconductor element manufacturing process or the like after that, the average resistivity is 1000 Ω · cm or more. A large change in resistivity of the silicon single crystal substrate that occurs in some cases can be suppressed.
また、本発明に従い、ＦＺ法により育成され、育成中に窒素を添加したシリコン単結晶インゴットをスライス切断して作製した、面内の平均抵抗率が１０００Ω・ｃｍ以上のシリコン単結晶基板の抵抗特性を測定する際に、９００〜１２５０℃の温度で１０〜１２０分の熱処理を行った後、前記作製したシリコン単結晶基板の抵抗率及び／又は面内抵抗率分布を測定するようにすれば、添加した窒素のドナーとしての作用が消去された後の抵抗特性を測定することになり、シリコン単結晶基板の抵抗特性はその後の半導体素子製造工程等での熱処理においても前記測定した抵抗特性から大きく変化しないので、１０００Ω・ｃｍ以上のような高抵抗率のシリコン単結晶基板の製造においても正確な抵抗特性の保証が可能になる。従ってこのように測定した抵抗特性を保証値として用いれば信頼度の高い抵抗特性の保証方法となる。 Further, according to the present invention, resistance characteristics of a silicon single crystal substrate having an in-plane average resistivity of 1000 Ω · cm or more, which is produced by slicing a silicon single crystal ingot grown by FZ method and added with nitrogen during the growth in accordance with the present invention When measuring the resistivity and / or in-plane resistivity distribution of the produced silicon single crystal substrate after performing heat treatment at a temperature of 900 to 1250 ° C. for 10 to 120 minutes, The resistance characteristic after the action of the added nitrogen as a donor is erased is measured, and the resistance characteristic of the silicon single crystal substrate is greatly increased from the measured resistance characteristic in the subsequent heat treatment in the semiconductor element manufacturing process and the like. Since it does not change, accurate resistance characteristics can be guaranteed even in the production of a silicon single crystal substrate having a high resistivity of 1000 Ω · cm or more. Therefore, if the resistance characteristic measured in this way is used as a guaranteed value, it becomes a highly reliable resistance characteristic guarantee method.
［図１］本発明に従ったシリコン単結晶基板の製造工程の一例を示す図である。
［図２］本発明に従ったシリコン単結晶基板の抵抗率及び／又は面内抵抗率分布測定工程の一例を示す図である。
［図３］本発明の実施例１における、熱処理によるシリコン単結晶基板の面内抵抗率分布の変化を示すグラフである。
［図４］本発明の実施例２における、Ｎ型又はＰ型のシリコン単結晶基板についての熱処理前の面内平均抵抗率に対する熱処理後の面内平均抵抗率を示すグラフである。
［図５］本発明の実施例３における、熱処理前のシリコン単結晶基板の面内抵抗率分布を示すグラフである。
［図６］本発明の実施例３における、熱処理後のシリコン単結晶基板の面内抵抗率分布を示すグラフである。
［図７］本発明の実施例４における、サンプルＡ〜Ｄの熱処理前後の面内抵抗率分布を示すグラフである。
［図８］本発明の実施例４における、シリコン単結晶基板の熱処理前の面内平均抵抗率に対する熱処理後のＲＲＧ変化を示すグラフである。FIG. 1 is a diagram showing an example of a manufacturing process of a silicon single crystal substrate according to the present invention.
FIG. 2 is a diagram showing an example of a resistivity and / or in-plane resistivity distribution measuring step for a silicon single crystal substrate according to the present invention.
FIG. 3 is a graph showing changes in the in-plane resistivity distribution of the silicon single crystal substrate by heat treatment in Example 1 of the present invention.
FIG. 4 is a graph showing the in-plane average resistivity after heat treatment with respect to the in-plane average resistivity before heat treatment for an N-type or P-type silicon single crystal substrate in Example 2 of the present invention.
FIG. 5 is a graph showing the in-plane resistivity distribution of the silicon single crystal substrate before heat treatment in Example 3 of the present invention.
FIG. 6 is a graph showing the in-plane resistivity distribution of the silicon single crystal substrate after heat treatment in Example 3 of the present invention.
FIG. 7 is a graph showing in-plane resistivity distributions of samples A to D before and after heat treatment in Example 4 of the present invention.
FIG. 8 is a graph showing a change in RRG after heat treatment with respect to the in-plane average resistivity before heat treatment of a silicon single crystal substrate in Example 4 of the present invention.
以下では、本発明の実施の形態について説明するが、本発明はこれに限定されるものではない。
本発明者らの調査によると、窒素を添加したシリコン単結晶基板において半導体製造工程中の熱処理により発生する抵抗率の変化は、シリコン単結晶基板の熱処理前の抵抗率が高いほど大きくなる。そして、近年需要が高まっている平均抵抗率が１０００Ω・ｃｍのシリコン単結晶基板においてはこの抵抗率の変化が顕著であり、特に熱処理前の抵抗率が３０００Ω・ｃｍを越えるものでは、熱処理前後の抵抗率の乖離が著しく大きくなっていた。Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.
According to the investigation by the present inventors, the change in the resistivity generated by the heat treatment in the semiconductor manufacturing process in the silicon single crystal substrate to which nitrogen is added becomes larger as the resistivity of the silicon single crystal substrate before the heat treatment is higher. The change in resistivity is remarkable in a silicon single crystal substrate having an average resistivity of 1000 Ω · cm, which has been increasing in demand in recent years, and particularly when the resistivity before the heat treatment exceeds 3000 Ω · cm, before and after the heat treatment. The difference in resistivity was remarkably large.
例えば、熱処理前の抵抗率が３０００Ω・ｃｍのＮ型シリコン単結晶基板の場合、熱処理後に抵抗率が３０％以上、すなわち９００Ω・ｃｍ以上も変化する場合があった。また、１００００Ω・ｃｍのものでは、１００％の変化率に達する場合があった。すなわち、熱処理前の抵抗率が１００００Ω・ｃｍのＮ型シリコン単結晶基板の場合には、熱処理により抵抗率が２００００Ω・ｃｍに達する場合があった。従ってそのようなシリコン単結晶基板を用いた半導体素子製造工程においては、例えば抵抗率が１００００Ω・ｃｍのシリコン単結晶基板を基にした設計の半導体素子製造工程を施しても、工程中の熱処理により抵抗率が２００００Ω・ｃｍとなる場合があり、その結果製造した半導体素子の特性が設計通りにならないといった問題を生じる。従って、半導体素子製造工程前に測定した抵抗率は信頼度の低い値となってしまう。 For example, in the case of an N-type silicon single crystal substrate having a resistivity of 3000 Ω · cm before the heat treatment, the resistivity may change by 30% or more, that is, 900 Ω · cm or more after the heat treatment. In addition, in the case of 10,000 Ω · cm, the rate of change of 100% may be reached. That is, in the case of an N-type silicon single crystal substrate having a resistivity of 10,000 Ω · cm before the heat treatment, the resistivity may reach 20000 Ω · cm by the heat treatment. Therefore, in a semiconductor element manufacturing process using such a silicon single crystal substrate, for example, even if a semiconductor element manufacturing process designed based on a silicon single crystal substrate having a resistivity of 10,000 Ω · cm is applied, In some cases, the resistivity may be 20000 Ω · cm, and as a result, the characteristics of the manufactured semiconductor element may not be as designed. Therefore, the resistivity measured before the semiconductor element manufacturing process has a low reliability value.
一方、シリコン単結晶基板の製造工程においては、例えば抵抗率が２００００Ω・ｃｍとなるようにＮ型不純物が添加されるよう設計してシリコン単結晶インゴットを育成したとしても、シリコン単結晶インゴットをスライス切断してシリコン単結晶基板を作製した時点での抵抗率が１００００Ω・ｃｍとなる場合があり、設計の精度の保証ができないといった問題を生じる。このような高抵抗率の結晶の育成では、わずかなドナーの発生でも抵抗率への影響が大きく、問題となることが判った。特に１０００Ω・ｃｍ以上で問題が大きくなることが判った。 On the other hand, in the process of manufacturing a silicon single crystal substrate, for example, even if a silicon single crystal ingot is grown by designing an N-type impurity so that the resistivity is 20000 Ω · cm, the silicon single crystal ingot is sliced. When the silicon single crystal substrate is cut to produce a resistivity, the resistivity may be 10,000 Ω · cm, which causes a problem that the design accuracy cannot be guaranteed. It has been found that in the growth of such high resistivity crystals, even the slight generation of donors has a large effect on the resistivity and becomes a problem. In particular, it has been found that the problem becomes large at 1000 Ω · cm or more.
ここで面内抵抗率分布に着目すると、例えば熱処理前の平均抵抗率が８０００Ω・ｃｍのＮ型シリコン単結晶基板の場合、熱処理前はＲＲＧが５０％程度の値であったものが、熱処理後には２０％程度にまで減少する場合があった。この場合、熱処理前と後のＲＲＧの差は３０％である。また、１００００Ω・ｃｍのものでは、熱処理前と後でのＲＲＧの差が６０％にも達する場合があった。このようにシリコン単結晶基板の平均抵抗率が高いほど面内抵抗率分布の変化率も高いので、正確な面内抵抗率分布の品質保証を大きく阻害する要因となる。 Focusing on the in-plane resistivity distribution, for example, in the case of an N-type silicon single crystal substrate having an average resistivity of 8000 Ω · cm before the heat treatment, the RRG before the heat treatment had a value of about 50%. Sometimes decreased to about 20%. In this case, the difference between the RRG before and after the heat treatment is 30%. In the case of 10,000 Ω · cm, the difference in RRG before and after the heat treatment sometimes reached 60%. As described above, the higher the average resistivity of the silicon single crystal substrate, the higher the rate of change of the in-plane resistivity distribution, which is a factor that greatly hinders the quality assurance of the accurate in-plane resistivity distribution.
従ってそのようなシリコン単結晶基板を用いた半導体素子製造工程においては、例えばＲＲＧが５０％の面内抵抗率分布をもつシリコン単結晶基板を基にした設計の半導体素子製造工程を施しても、工程中の熱処理によりＲＲＧが２０％程度となる場合があり、その結果製造した半導体素子の特性が設計通りにならないといった問題を生じる。さらに、ＲＲＧを不適当に高く見積もってしまうことにより、均一な抵抗率をもつ半導体素子の製品収率を不適当に低く見積もってしまう可能性もある。従って、半導体素子製造工程前に測定したＲＲＧ等の面内抵抗率分布の値は信頼度の低い値となってしまう。 Accordingly, in a semiconductor element manufacturing process using such a silicon single crystal substrate, for example, even if a semiconductor element manufacturing process designed based on a silicon single crystal substrate having an in-plane resistivity distribution with an RRG of 50% is performed, The RRG may be about 20% due to the heat treatment in the process, and as a result, there arises a problem that the characteristics of the manufactured semiconductor element are not as designed. Further, if the RRG is estimated to be inappropriately high, the product yield of a semiconductor element having a uniform resistivity may be estimated to be inappropriately low. Therefore, the value of the in-plane resistivity distribution such as RRG measured before the semiconductor element manufacturing process becomes a low reliability value.
一方、シリコン単結晶基板の製造工程においては、例えば基板の製品規格値がＲＲＧで２０％以下であるような場合に、ある基板の測定したＲＲＧが５０％であれば規格外であるが、そのような基板であってもその後の熱処理でＲＲＧが低下して規格値を満たすような場合が起こる。そのような場合には面内抵抗率分布の値が信頼度の低い値となるだけでなく、シリコン単結晶基板製品の収率を著しく悪化させてしまうこととなる。 On the other hand, in the manufacturing process of a silicon single crystal substrate, for example, when the product standard value of the substrate is 20% or less in RRG, if the RRG measured for a certain substrate is 50%, it is out of specification. Even if such a substrate is used, there is a case where the RRG is lowered by the subsequent heat treatment to satisfy the standard value. In such a case, the value of the in-plane resistivity distribution not only has a low reliability value, but also significantly deteriorates the yield of the silicon single crystal substrate product.
このようなＲＲＧの変化が起こる理由は以下のようなものと考えられる。窒素は転位や結晶欠陥の抑制のために添加されるが、Ｎ型ドナーとしても作用する。ここで窒素は、単結晶成長時の境界拡散層の不均一分布及び温度分布の不均一性により基板面内に不均一に含まれているため、結果として面内抵抗率分布が不均一になっている。このときＲＲＧも大きい値となる。この現象はシリコン単結晶基板の抵抗率が高いほど、結晶に本来抵抗率調整のために添加されるドナーの量が少ないため、それにするドナーとして作用する窒素の量の比率が大きくなるので影響が大きく、ドナー消去熱処理による面内抵抗率分布の変動が大きくなる。このような窒素の分布の不均一性は、ＦＺ法により育成されたシリコン単結晶インゴットから作製されたシリコン単結晶基板において特に顕著である。また、シリコン単結晶インゴットの直径が１００ｍｍ、１５０ｍｍと大きくなるにつれてさらに顕著なものとなる。 The reason why such a change in RRG occurs is considered as follows. Nitrogen is added to suppress dislocations and crystal defects, but also acts as an N-type donor. Here, nitrogen is unevenly contained in the substrate plane due to the nonuniform distribution of the boundary diffusion layer and the nonuniformity of the temperature distribution during single crystal growth. As a result, the in-plane resistivity distribution becomes nonuniform. ing. At this time, RRG also has a large value. This phenomenon has an effect because the higher the resistivity of the silicon single crystal substrate, the smaller the amount of donor that is originally added to the crystal for adjusting the resistivity, so the ratio of the amount of nitrogen acting as a donor to it becomes larger. Largely, the fluctuation of the in-plane resistivity distribution due to the donor erasing heat treatment becomes large. Such non-uniformity of nitrogen distribution is particularly remarkable in a silicon single crystal substrate manufactured from a silicon single crystal ingot grown by the FZ method. Moreover, it becomes more remarkable as the diameter of the silicon single crystal ingot increases to 100 mm and 150 mm.
以上の点に鑑み、本発明者らは、シリコン単結晶基板に９００〜１２５０℃の温度で１０〜１２０分の熱処理を行えば、窒素を添加した平均抵抗率１０００Ω・ｃｍ以上の高抵抗率のシリコン単結晶基板であっても、その後の半導体素子製造工程等で熱処理を行っても前述のような著しい抵抗率の変化が発生しないことを見出した。
また、このように９００〜１２５０℃の温度で１０〜１２０分の熱処理を行った後に抵抗率や面内抵抗率分布等の抵抗特性の測定を行えば、その後の半導体素子製造工程等で熱処理を行っても前述のような著しい抵抗特性の変化が発生しないようにすることができ（熱処理してから抵抗特性を測定することになり）、信頼度の高い抵抗特性保証ができることを見出し、本発明を完成させた。In view of the above points, the present inventors can perform a heat treatment for 10 to 120 minutes at a temperature of 900 to 1250 ° C. on a silicon single crystal substrate, and have an average resistivity of 1000 Ω · cm or higher with nitrogen added. It has been found that even when a silicon single crystal substrate is used, a significant change in resistivity as described above does not occur even when heat treatment is performed in a subsequent semiconductor element manufacturing process or the like.
In addition, if resistance characteristics such as resistivity and in-plane resistivity distribution are measured after performing heat treatment at 900 to 1250 ° C. for 10 to 120 minutes in this way, the heat treatment is performed in subsequent semiconductor element manufacturing processes and the like. It has been found that the above-described significant change in resistance characteristics can be prevented even if the process is performed (the resistance characteristics are measured after heat treatment), and the resistance characteristics can be assured with high reliability. Was completed.
以下では、本発明の一例を図を参照して詳細に説明する。
図１は、本発明に従ったシリコン単結晶基板の製造工程の一例を示す図であり、図２は、本発明に従ったシリコン単結晶基板の抵抗率及び／又は面内抵抗率分布測定工程の一例を示す図である。はじめに、図１を用いて、シリコン単結晶基板の製造工程について説明する。Hereinafter, an example of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing an example of a manufacturing process of a silicon single crystal substrate according to the present invention, and FIG. 2 is a process for measuring resistivity and / or in-plane resistivity distribution of a silicon single crystal substrate according to the present invention. It is a figure which shows an example. First, a manufacturing process of a silicon single crystal substrate will be described with reference to FIG.
まず、従来のＦＺ法による単結晶製造装置により抵抗率を１０００Ω・ｃｍ以上の所望の値に設定してシリコン単結晶インゴットを育成する（図１Ａ）。抵抗率を所望の値とするためにＮ型またはＰ型の不純物を育成中に添加することもできる。例えばＰＨ３、ＳｂＨ３、ＡｓＨ３等の原料ガスをアルゴンガス等のキャリアガスで希釈して溶融帯に吹き付けることによりＮ型不純物であるＰ、Ｓｂ、Ａｓを添加することができる。Ｐ型不純物であるＢを添加するにはＢ２Ｈ６等を原料ガスとすればよい。First, a silicon single crystal ingot is grown by setting the resistivity to a desired value of 1000 Ω · cm or more by a conventional single crystal manufacturing apparatus using the FZ method (FIG. 1A). N-type or P-type impurities can also be added during growth in order to obtain a desired resistivity. For example, it is possible to add P, Sb, and As that are N-type impurities by diluting a source gas such as PH 3 , SbH 3 , AsH 3 or the like with a carrier gas such as argon gas and spraying it on the melting zone. In order to add B which is a P-type impurity, B 2 H 6 or the like may be used as a source gas.
そして、シリコン単結晶インゴットの育成中に、単結晶製造装置の炉内をアルゴンガス又はアルゴンと水素の混合ガスからなる雰囲気ガスで満たし、そこに窒素ガス又は窒素を含む化合物ガスを混合することにより、シリコン単結晶インゴットに窒素を添加する。窒素を含む化合物ガスとしてはアンモニア、ヒドラジン、三フッ化窒素等のガスを用いることができる。このとき添加される窒素は、シリコン単結晶インゴット育成時にスワールやＤ欠陥等の結晶欠陥が発生するのを防止し、またシリコン単結晶基板に熱処理を加えた際に熱応力により発生する転位を抑制する作用がある。特に添加する窒素濃度が３×１０１４ａｔｏｍｓ／ｃｍ３以上であれば、上記の結晶欠陥や転位の抑制に十分な濃度であり、かつ後述する本発明の効果を十分なものとすることができる。Then, during the growth of the silicon single crystal ingot, the furnace of the single crystal production apparatus is filled with an atmosphere gas composed of argon gas or a mixed gas of argon and hydrogen, and nitrogen gas or a compound gas containing nitrogen is mixed therein. Then, nitrogen is added to the silicon single crystal ingot. As the compound gas containing nitrogen, a gas such as ammonia, hydrazine, or nitrogen trifluoride can be used. The nitrogen added at this time prevents the occurrence of crystal defects such as swirl and D defects during the growth of a silicon single crystal ingot, and also suppresses dislocations caused by thermal stress when heat treatment is applied to the silicon single crystal substrate. Has the effect of In particular, when the concentration of nitrogen to be added is 3 × 10 14 atoms / cm 3 or more, the concentration is sufficient for suppressing the above crystal defects and dislocations, and the effects of the present invention described later can be made sufficient. .
このとき添加される窒素は、境界拡散層の不均一分布及び温度分布の不均一性等により、面内に不均一に含まれる。このため、窒素のドナーとしての作用により、面内抵抗率分布が不均一となる原因となる。特にシリコン単結晶インゴットをＦＺ法により育成する場合、ＦＺ法では溶融帯の融液容量が比較的小さく自然対流により添加物が単結晶に不均一に取り込まれやすいので、不均一性が顕著になる。 Nitrogen added at this time is non-uniformly contained in the plane due to the non-uniform distribution of the boundary diffusion layer and the non-uniformity of the temperature distribution. For this reason, the in-plane resistivity distribution becomes non-uniform due to the action of nitrogen as a donor. In particular, when a silicon single crystal ingot is grown by the FZ method, the melt capacity of the melt zone is relatively small in the FZ method, and the additive tends to be incorporated non-uniformly into the single crystal by natural convection, so the non-uniformity becomes remarkable. .
次に、このようにして育成したシリコン単結晶インゴットを円筒ブロック状に切断し、外径研削した後に必要に応じてオリエンテーションフラット加工を施す（図１Ｂ）。そしてこのようにして加工したシリコン単結晶インゴットを内周刃スライサーやワイヤソー等を用いて所定の厚さにスライス切断してシリコン単結晶基板を作製する（図１Ｃ）。このように作製したシリコン単結晶基板に基板加工を施す（図１Ｄ）。具体的には、基板周辺のカケやチップを防ぐための面取り加工や、基板表面の平坦度と面平行度を高めるためのラッピング加工であり、その後にエッチング処理して上記機械加工プロセスで生じた表面の破砕層を除去する。さらに必要に応じて半導体素子製造工程で行われるゲッタリング熱処理の準備工程として裏面ゲッタリング処理を行う。この裏面ゲッタリング処理は、数〜数十μｍの粒径のＳｉＯ２で基板裏面をサンドブラスティングあるいは回転研磨して機械的ダメージ層を導入することより行うことができる。これらの工程はいずれも従来知られた方法で行うことができるものである。このようにして作製されたシリコン単結晶基板に後述する熱処理を行い（図１Ｅ）、その後表面を鏡面研磨してシリコン単結晶基板を製造する（図１Ｆ）。Next, the silicon single crystal ingot grown in this manner is cut into a cylindrical block shape, and after being subjected to outer diameter grinding, orientation flat processing is performed as necessary (FIG. 1B). Then, the silicon single crystal ingot processed in this way is sliced and cut into a predetermined thickness using an inner peripheral blade slicer, a wire saw, or the like to produce a silicon single crystal substrate (FIG. 1C). Substrate processing is performed on the silicon single crystal substrate thus manufactured (FIG. 1D). Specifically, chamfering to prevent chipping and chips around the substrate and lapping to increase the flatness and surface parallelism of the substrate surface, and then the etching process caused by the above machining process Remove the crush layer on the surface. Further, a back surface gettering process is performed as a preparation process for the gettering heat treatment performed in the semiconductor element manufacturing process as necessary. This back surface gettering treatment can be performed by introducing a mechanical damage layer by sandblasting or rotationally polishing the back surface of the substrate with SiO 2 having a particle diameter of several to several tens of μm. Any of these steps can be performed by a conventionally known method. The thus-prepared silicon single crystal substrate is heat-treated as described later (FIG. 1E), and then the surface is mirror-polished to produce a silicon single crystal substrate (FIG. 1F).
前述の熱処理（図１Ｅ）は９００〜１２５０℃の温度で１０〜１２０分間行うことが好ましい。このような温度であれば、熱処理時間が長時間に及ぶことがなく、また加熱冷却時に熱応力により結晶欠陥が発生する可能性を小さくすることができるので特に好適である。熱処理の際の昇温速度については、例えば毎分１℃〜１０℃とすることができるが、熱処理を受けるシリコン単結晶基板が急激な昇温により発生する熱応力によりスリップが発生したり、極端なケースでは破壊されたり、あるいは結晶性が劣化したりしない限り自由に選ぶことができる。 The aforementioned heat treatment (FIG. 1E) is preferably performed at a temperature of 900 to 1250 ° C. for 10 to 120 minutes. Such a temperature is particularly preferable because the heat treatment does not take a long time and the possibility of crystal defects due to thermal stress during heating and cooling can be reduced. The rate of temperature increase during the heat treatment can be, for example, 1 ° C. to 10 ° C. per minute. However, the silicon single crystal substrate subjected to the heat treatment may slip due to thermal stress generated by a rapid temperature increase, In such cases, it can be freely selected as long as it is not destroyed or the crystallinity is deteriorated.
シリコン単結晶基板がＮ型の場合、この熱処理により抵抗率が上昇する。すなわち、Ｎ型シリコン単結晶基板の場合は、添加された窒素が添加されたＮ型不純物と同様にドナーとして作用するため、本来シリコン単結晶基板にＮ型不純物により与えられる抵抗率と比較して見かけの抵抗率が低い事に由来すると推測される。この場合、熱処理を行うことにより窒素のドナーとしての作用が消去され、シリコン単結晶基板本来の抵抗率に回復した結果、抵抗率が上昇したように見える。このようにシリコン単結晶基板の抵抗率がＮ型不純物により与えられる本来の抵抗率に回復すれば、その後シリコン単結晶基板に半導体素子製造工程等で熱処理を行っても、抵抗率は変化しない。 When the silicon single crystal substrate is N-type, the heat resistance increases the resistivity. That is, in the case of an N-type silicon single crystal substrate, it acts as a donor in the same manner as an N-type impurity to which added nitrogen is added, so that it is compared with the resistivity originally given to the silicon single-crystal substrate by the N-type impurity. It is presumed to originate from the fact that the apparent resistivity is low. In this case, the effect of nitrogen as a donor is eliminated by performing the heat treatment, and it appears that the resistivity has increased as a result of restoring the original resistivity of the silicon single crystal substrate. Thus, if the resistivity of the silicon single crystal substrate is restored to the original resistivity given by the N-type impurities, the resistivity does not change even if the silicon single crystal substrate is subsequently heat-treated in a semiconductor element manufacturing process or the like.
さらにドナーとしての窒素は、単結晶成長時の境界拡散層の不均一分布及び温度分布の不均一性により基板面内に不均一に含まれているため、結果として面内抵抗率分布が不均一になっており、そのためＲＲＧも大きい値を示す。この現象は特にＦＺ法で単結晶を育成した場合に顕著である。しかし前記熱処理を行うことにより基板面内に不均一に分布していた窒素のドナーとしての作用が消去され、シリコン単結晶基板本来の面内抵抗率分布が顕在した結果、ＲＲＧが低下する。この現象はシリコン単結晶基板の抵抗率が高いほど、結晶に本来抵抗率調整のために添加されるＮ型不純物の量が少なく、それに対するドナーとして作用する窒素の量の比率が大きくなるため影響が大きく、ドナー消去による面内抵抗率分布の変動が大きくなる。このようにシリコン単結晶基板のＲＲＧがＮ型不純物により与えられる本来のＲＲＧに回復すれば、その後シリコン単結晶基板に半導体素子製造工程等で熱処理を行っても、ＲＲＧは変化しない。 Furthermore, nitrogen as a donor is included in the substrate plane non-uniformly due to non-uniform distribution of the boundary diffusion layer and temperature distribution during single crystal growth, resulting in non-uniform in-plane resistivity distribution. Therefore, RRG also shows a large value. This phenomenon is particularly noticeable when a single crystal is grown by the FZ method. However, by performing the heat treatment, the nitrogen non-uniform distribution in the substrate surface is eliminated, and the intrinsic in-plane resistivity distribution of the silicon single crystal substrate is manifested, resulting in a decrease in RRG. This phenomenon is influenced by the fact that the higher the resistivity of a silicon single crystal substrate, the smaller the amount of N-type impurities originally added to the crystal for adjusting the resistivity, and the larger the ratio of the amount of nitrogen acting as a donor to that. And the fluctuation of the in-plane resistivity distribution due to donor erasure increases. As described above, if the RRG of the silicon single crystal substrate is restored to the original RRG given by the N-type impurity, the RRG does not change even if the silicon single crystal substrate is subsequently heat-treated in the semiconductor element manufacturing process or the like.
一方、シリコン単結晶基板がＰ型の場合、この熱処理により抵抗率が低下する。すなわち、Ｐ型シリコン単結晶基板の場合は、アクセプターとしてのＰ型不純物の方が優勢であることから、添加された窒素がドナーとして抵抗率にＰ型不純物とは逆の寄与をするために、本来シリコン単結晶基板にＰ型不純物により与えられる抵抗率と比較して見かけの抵抗率が上昇していることになる。従って、熱処理を行うことにより窒素のドナーとしての作用が消去され、シリコン単結晶基板本来の抵抗率に回復した結果、抵抗率が低下したように見える。このようにシリコン単結晶基板の抵抗率がＰ型不純物により与えられる本来の抵抗率に回復すれば、その後シリコン単結晶基板に半導体素子製造工程等で熱処理を行っても、抵抗率は変化しない。 On the other hand, when the silicon single crystal substrate is P-type, this heat treatment reduces the resistivity. That is, in the case of a P-type silicon single crystal substrate, since the P-type impurity as an acceptor is more dominant, the added nitrogen serves as a donor to contribute to the resistivity in the opposite direction to the P-type impurity. The apparent resistivity is increased as compared with the resistivity inherently given to the silicon single crystal substrate by the P-type impurities. Therefore, the heat treatment erases the action of nitrogen as a donor, and as a result of restoring the original resistivity of the silicon single crystal substrate, it seems that the resistivity is lowered. As described above, if the resistivity of the silicon single crystal substrate is restored to the original resistivity given by the P-type impurities, the resistivity does not change even if the silicon single crystal substrate is subsequently heat-treated in a semiconductor element manufacturing process or the like.
この場合も、ドナーとしての窒素が基板面内に不均一に含まれているため、結果として面内抵抗率分布が不均一になっており、そのためＲＲＧも大きい値を示す。しかし前記熱処理を行うことにより不均一に分布していた窒素のドナーとしての作用が消去され、シリコン単結晶基板本来の面内抵抗率分布が顕在した結果、ＲＲＧが低下する。 Also in this case, since nitrogen as a donor is non-uniformly contained in the substrate surface, the in-plane resistivity distribution is non-uniform as a result, and therefore RRG also shows a large value. However, when the heat treatment is performed, the non-uniform distribution of nitrogen as a donor is eliminated, and the intrinsic in-plane resistivity distribution of the silicon single crystal substrate becomes apparent. As a result, RRG is lowered.
いずれの場合でも、平均抵抗率が１０００Ω・ｃｍ以上のような高抵抗率の場合は、Ｎ型またはＰ型不純物の濃度が比較的小さいため、転位や結晶欠陥の発生を抑制するために添加された窒素がドナーとして見かけの抵抗率及び面内抵抗率分布に寄与する割合が大きい。従ってこのような熱処理により窒素のドナーとしての作用を消去してシリコン単結晶基板の抵抗率を本来の抵抗率及び面内抵抗率分布に回復させる効果も著しく高いことになる。特に窒素濃度が３×１０１４ａｔｏｍｓ／ｃｍ３以上であれば、窒素のドナーとしての見かけの面内抵抗率分布に対する寄与が十分に大きいため、熱処理の効果はより高いものになる。また、シリコン単結晶基板の直径が大きいほど窒素の不均一な分布による面内抵抗率分布の不均一性が大きく、ＲＲＧも大きくなる傾向があるので、熱処理によりＲＲＧを本来の値に回復させる効果が高いものとなる。In any case, in the case of a high resistivity such as an average resistivity of 1000 Ω · cm or higher, the concentration of N-type or P-type impurities is relatively small, so it is added to suppress the occurrence of dislocations and crystal defects. Nitrogen contributes to the apparent resistivity and in-plane resistivity distribution as a donor. Accordingly, the effect of restoring the resistivity of the silicon single crystal substrate to the original resistivity and in-plane resistivity distribution by eliminating the action of nitrogen as a donor by such heat treatment is remarkably high. In particular, when the nitrogen concentration is 3 × 10 14 atoms / cm 3 or more, the effect of the heat treatment becomes higher because the contribution to the apparent in-plane resistivity distribution as a donor of nitrogen is sufficiently large. In addition, the larger the diameter of the silicon single crystal substrate, the greater the non-uniformity of the in-plane resistivity distribution due to the non-uniform distribution of nitrogen, and the RRG also tends to increase. Therefore, the effect of recovering RRG to its original value by heat treatment Is expensive.
また、熱処理を行う際には、ウェット酸素雰囲気、ドライ酸素雰囲気、窒素雰囲気のいずれか１つの雰囲気下でおこなうことが好ましい。これらの雰囲気下であれば、熱処理を効果的に行うことができる。窒素を添加したシリコン単結晶基板内では、窒素分子が原子空孔と複合体を形成してドナーとして作用していると考えられるが、酸素雰囲気下で熱処理すると、シリコン単結晶基板の表面にＳｉＯ２膜が形成されることにより格子間Ｓｉが内方拡散され、原子空孔が消滅し、ドナー作用が消去される。ウェット酸素雰囲気とドライ酸素雰囲気では、ウェット酸素雰囲気の方がＳｉＯ２膜の形成速度が速いので、熱処理がより効果的となる。窒素雰囲気の場合は、ドナー作用の消去に関して、格子間Ｓｉの内方拡散のみならず原子空孔の外方拡散による効果が大きいものと推測される。In addition, the heat treatment is preferably performed in any one of a wet oxygen atmosphere, a dry oxygen atmosphere, and a nitrogen atmosphere. Under these atmospheres, heat treatment can be effectively performed. In the silicon single crystal substrate to which nitrogen is added, it is considered that nitrogen molecules form a complex with atomic vacancies and act as a donor. However, when heat treatment is performed in an oxygen atmosphere, SiO is formed on the surface of the silicon single crystal substrate. By forming two films, interstitial Si is diffused inward, atomic vacancies disappear, and donor action is eliminated. In the wet oxygen atmosphere and the dry oxygen atmosphere, the wet oxygen atmosphere has a faster formation rate of the SiO 2 film, so that the heat treatment becomes more effective. In the case of a nitrogen atmosphere, it is presumed that the effect of not only the in-diffusion of interstitial Si but also the out-diffusion of atomic vacancies is significant in eliminating the donor action.
次に、図２を用いて、シリコン単結晶基板の抵抗率及び／又は面内抵抗率分布測定工程について説明する。図２Ａ〜図２Ｅの工程については前記の図１Ａ〜図１Ｅの工程と同一である。 Next, the resistivity and / or in-plane resistivity distribution measurement process of the silicon single crystal substrate will be described with reference to FIG. The steps of FIGS. 2A to 2E are the same as the steps of FIGS. 1A to 1E.
そして、このようにして熱処理を行なった（図２Ｅ）シリコン単結晶基板の抵抗率及び／又は面内抵抗率分布等の抵抗特性を測定する（図２Ｆ）。抵抗特性は例えば四探針法、広がり抵抗法、ホール効果法等で行うことができ、抵抗率の均一性の指標としてＲＲＧ等を用いることができる。前述のように本発明では熱処理により抵抗率はＮ型又はＰ型不純物により与えられる本来の抵抗率に回復しているので、この時測定した抵抗特性は、その後の半導体素子製造工程等で施される様々な熱処理の後の抵抗特性とほぼ同一である。従ってこのように熱処理後に抵抗特性を測定すれば、例えば半導体素子製造工程等で素子特性の設計をする場合などにこのように測定した抵抗率やＲＲＧ等を保証値として用いることができ、１０００Ω・ｃｍ以上の高抵抗率であっても、製造工程中の熱処理により素子特性が変化せずに、設計どおりの素子製造が可能となる。 And the resistance characteristics such as resistivity and / or in-plane resistivity distribution of the silicon single crystal substrate subjected to the heat treatment in this way (FIG. 2E) are measured (FIG. 2F). The resistance characteristic can be performed by, for example, a four-probe method, a spreading resistance method, a Hall effect method, or the like, and RRG or the like can be used as an index of resistivity uniformity. As described above, in the present invention, the resistivity is restored to the original resistivity given by the N-type or P-type impurities by the heat treatment, and thus the measured resistance characteristics are applied in the subsequent semiconductor element manufacturing process or the like. The resistance characteristics after various heat treatments are almost the same. Therefore, if the resistance characteristics are measured after the heat treatment in this way, the resistivity, RRG, etc. measured in this way can be used as guaranteed values, for example, when designing the element characteristics in the semiconductor element manufacturing process, etc. Even if the resistivity is not less than cm, the device characteristics can be manufactured as designed without changing the device characteristics due to the heat treatment during the manufacturing process.
またシリコン単結晶基板の製造工程においては、このような熱処理後に測定した抵抗特性を用いて製造設計を行えばより設計精度の高い製造工程とすることができる。また、シリコン単結晶基板の製造ロットの抵抗率及び／又はＲＲＧを、ロットから適宜選択したシリコン単結晶基板の抵抗率及び／又はＲＲＧで代表させて保証するような場合でも、その代表させる基板をこのように熱処理した後に抵抗率及び／又はＲＲＧを測定し、それを保証値として用いることにより、その製造ロットの全てのシリコン単結晶基板を熱処理して抵抗率及び／又はＲＲＧを測定しなくても、それらのシリコン単結晶基板の本来の抵抗率及び／又はＲＲＧを保証することが可能になる。 Moreover, in the manufacturing process of a silicon single crystal substrate, if manufacturing design is performed using the resistance characteristics measured after such heat treatment, a manufacturing process with higher design accuracy can be achieved. Further, even when the resistivity and / or RRG of the production lot of the silicon single crystal substrate is represented by the resistivity and / or RRG of the silicon single crystal substrate appropriately selected from the lot, the substrate to be represented is guaranteed. By measuring the resistivity and / or RRG after the heat treatment in this manner and using it as a guaranteed value, it is possible to heat-treat all the silicon single crystal substrates of the production lot and measure the resistivity and / or RRG. However, it becomes possible to guarantee the original resistivity and / or RRG of those silicon single crystal substrates.
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。 Examples of the present invention will be described in more detail below, but the present invention is not limited thereto.
直径１２５ｍｍのＮ型シリコン単結晶インゴットをＦＺ法により育成し、育成中に窒素ガスにより窒素を添加した。このときの添加された窒素の全てがドナーとして作用するわけではないが、少なくともドナーとして作用する窒素の濃度は後述するように約５ｐｐｔａ（＝２．５×１０１１ａｔｏｍｓ／ｃｍ３）と見積もられる。次に、該育成したシリコン単結晶インゴットをスライス切断して面方位｛１１１｝のシリコン単結晶基板を作製した。該作製したシリコン単結晶基板の面内の抵抗率分布を測定したところ、面内の平均抵抗率（Ｒａｖｅ）は１５８５Ω・ｃｍであった。An N-type silicon single crystal ingot having a diameter of 125 mm was grown by the FZ method, and nitrogen was added by nitrogen gas during the growth. Not all of the added nitrogen at this time acts as a donor, but at least the concentration of nitrogen acting as a donor is estimated to be about 5 ppta (= 2.5 × 10 11 atoms / cm 3 ) as described later. . Next, the grown silicon single crystal ingot was sliced to produce a silicon single crystal substrate having a plane orientation {111}. When the in-plane resistivity distribution of the produced silicon single crystal substrate was measured, the in-plane average resistivity (Rave) was 1585 Ω · cm.
前記作製したシリコン単結晶基板にドライ酸素雰囲気下で、１２００℃、１００分の熱処理を行った。該熱処理後のシリコン単結晶基板の面内の抵抗率分布を測定したところ、面内の平均抵抗率（Ｒａｖｅ）は熱処理前の平均抵抗率より８．９％程度上昇し、１７２７Ω・ｃｍであった。この後シリコン単結晶基板に試験的に６００〜１３００℃の熱処理を行ったが、面内の平均抵抗率は１７２７Ω・ｃｍからほとんど変化しなかった。この結果から、このシリコン単結晶基板の抵抗率の保証値を１７２７Ω・ｃｍとした。 The manufactured silicon single crystal substrate was heat-treated at 1200 ° C. for 100 minutes in a dry oxygen atmosphere. When the in-plane resistivity distribution of the silicon single crystal substrate after the heat treatment was measured, the in-plane average resistivity (Rave) was about 8.9% higher than the average resistivity before the heat treatment, and was 1727 Ω · cm. It was. Thereafter, a heat treatment at 600 to 1300 ° C. was experimentally performed on the silicon single crystal substrate, but the in-plane average resistivity hardly changed from 1727 Ω · cm. From this result, the guaranteed value of resistivity of this silicon single crystal substrate was set to 1727 Ω · cm.
図３は上記熱処理によるシリコン単結晶基板の面内抵抗率分布の変化を示すグラフである。横軸はシリコン単結晶基板の中心からの距離（ｍｍ）を示し、縦軸は抵抗率（Ω・ｃｍ）を示す。上記のようなドライ酸素雰囲気下で１２００℃、１００分の熱処理を行うことにより特にシリコン単結晶基板の中心部で抵抗率が大きく上昇する様子が示されている。前述のように、本実施例では、上昇後の抵抗率である１７２７Ω・ｃｍをこのシリコン単結晶基板の抵抗率の保証値とした。なお、このときの抵抗率の上昇は窒素のドナーとしての作用の消去によるものと考えられるので、シリコン単結晶インゴット育成中に添加された窒素によるドナー濃度は前述のように約５ｐｐｔａと見積もられる。 FIG. 3 is a graph showing changes in the in-plane resistivity distribution of the silicon single crystal substrate by the heat treatment. The horizontal axis indicates the distance (mm) from the center of the silicon single crystal substrate, and the vertical axis indicates the resistivity (Ω · cm). It is shown that the resistivity is greatly increased by performing the heat treatment at 1200 ° C. for 100 minutes in the dry oxygen atmosphere as described above, particularly in the central portion of the silicon single crystal substrate. As described above, in this example, the increased resistivity of 1727 Ω · cm was set as the guaranteed value of resistivity of the silicon single crystal substrate. In addition, since it is thought that the increase in resistivity at this time is due to elimination of the action of nitrogen as a donor, the donor concentration by nitrogen added during the growth of the silicon single crystal ingot is estimated to be about 5 ppta as described above.
直径１２５ｍｍのＮ型又はＰ型シリコン単結晶インゴットをＦＺ法により育成し、育成中に窒素ガスにより窒素を添加した。このときの添加された窒素のうち、少なくともドナーとして作用する窒素の濃度は後述するように約５ｐｐｔａと見積もられる。該育成したシリコン単結晶インゴットをスライス切断して面方位｛１１１｝のシリコン単結晶基板を作製した。このようにしてＮ型又はＰ型シリコン単結晶基板を様々な抵抗率でそれぞれ４０枚又は１０枚だけ作製した。このように作製したシリコン単結晶基板の面内の平均抵抗率を測定し、これらのシリコン単結晶基板にドライ酸素雰囲気下で、１２００℃、１００分の熱処理を行い、その後に再び面内の平均抵抗率を測定した。 An N-type or P-type silicon single crystal ingot having a diameter of 125 mm was grown by the FZ method, and nitrogen was added by nitrogen gas during the growth. Of the nitrogen added at this time, the concentration of at least nitrogen acting as a donor is estimated to be about 5 ppta as described later. The grown silicon single crystal ingot was sliced to produce a silicon single crystal substrate having a plane orientation of {111}. In this way, only 40 or 10 N-type or P-type silicon single crystal substrates were produced with various resistivity, respectively. The in-plane average resistivity of the silicon single crystal substrates thus produced was measured, and these silicon single crystal substrates were subjected to heat treatment at 1200 ° C. for 100 minutes in a dry oxygen atmosphere, and then the in-plane average was again measured. The resistivity was measured.
図４は、上記のＮ型又はＰ型のシリコン単結晶基板についての、熱処理前の面内平均抵抗率に対する熱処理後の面内平均抵抗率を示すグラフである。黒丸又は黒四角で表された点はそれぞれ上記で測定した熱処理後のＮ型又はＰ型のシリコン単結晶基板の面内平均抵抗率の実測値を示し、実線はドナーとして作用する窒素の濃度が５ｐｐｔａであると仮定した場合の熱処理後の面内平均抵抗率の理論値を示す。熱処理後のＮ型又はＰ型のシリコン単結晶基板の面内平均抵抗率の実測値はそれぞれ、前述した窒素のドナー作用の消去の効果により上昇又は低下している。実測値は理論値とほぼ適合する結果となっており、シリコン単結晶インゴット育成中に添加された窒素によるドナー濃度は前述のように約５ｐｐｔａと見積もられる。また、図４に示されるように、熱処理前の抵抗率が高ければ高いほど熱処理後の抵抗率の変化率が大きく、１０００Ω・ｃｍ以上の抵抗率において熱処理が必要であり、特に熱処理前の抵抗率で３０００Ω・ｃｍを越えると熱処理前後の抵抗率の乖離が大きくなり、本発明に従って９００〜１２５０℃の温度で１０〜１２０分の熱処理を行い、窒素のドナーとしての作用を消去することにより、シリコン単結晶基板の抵抗率はＮ型又はＰ型不純物により与えられる本来の抵抗率に回復するので、その後の工程中にシリコン単結品基板の抵抗率の変化を抑制することができる。そして、本発明に従う熱処理後にシリコン単結晶基板の抵抗率測定を行ってそれを保証値とすれば、その保証値を信頼度の高いものとできる。 FIG. 4 is a graph showing the in-plane average resistivity after the heat treatment with respect to the in-plane average resistivity before the heat treatment for the N-type or P-type silicon single crystal substrate. The points represented by black circles or black squares show the measured values of the in-plane average resistivity of the N-type or P-type silicon single crystal substrate after the heat treatment measured above, respectively, and the solid line shows the concentration of nitrogen acting as a donor The theoretical value of the in-plane average resistivity after heat treatment when it is assumed to be 5 ppta is shown. The measured values of the in-plane average resistivity of the N-type or P-type silicon single crystal substrate after the heat treatment are increased or decreased due to the above-described effect of eliminating the donor action of nitrogen. The actually measured value is a result that almost matches the theoretical value, and the donor concentration by nitrogen added during the growth of the silicon single crystal ingot is estimated to be about 5 ppta as described above. Further, as shown in FIG. 4, the higher the resistivity before heat treatment, the larger the rate of change in resistivity after heat treatment, and heat treatment is necessary at a resistivity of 1000 Ω · cm or more. When the rate exceeds 3000 Ω · cm, the difference in resistivity before and after the heat treatment increases, and according to the present invention, the heat treatment is performed at a temperature of 900 to 1250 ° C. for 10 to 120 minutes to eliminate the action of nitrogen as a donor, Since the resistivity of the silicon single crystal substrate is restored to the original resistivity given by the N-type or P-type impurities, it is possible to suppress the change in the resistivity of the single-crystal silicon substrate during the subsequent steps. Then, if the resistivity of the silicon single crystal substrate is measured after the heat treatment according to the present invention and set as a guaranteed value, the guaranteed value can be made highly reliable.
直径１２５ｍｍのＮ型シリコン単結晶インゴットをＦＺ法により育成し、育成中に窒素ガスにより窒素を添加した。次に、該育成したシリコン単結晶インゴットをスライス切断して面方位｛１１１｝のシリコン単結晶基板を作製し、面内抵抗率分布を測定した。図５はこのようにして測定した面内抵抗率分布を示すグラフである。横軸は測定点の基板上の位置を示し、Ｃｔｒは基板中心位置、Ｒ／２は基板中心から基板半径の１／２の位置、そしてＥｄｇｅは基板周辺位置を示す。また縦軸は抵抗率を示す。この結果からＲＲＧを算出したところ、ＲＲＧ＝５６．６％であった。 An N-type silicon single crystal ingot having a diameter of 125 mm was grown by the FZ method, and nitrogen was added by nitrogen gas during the growth. Next, the grown silicon single crystal ingot was sliced to produce a silicon single crystal substrate with a plane orientation of {111}, and the in-plane resistivity distribution was measured. FIG. 5 is a graph showing the in-plane resistivity distribution measured in this manner. The abscissa indicates the position of the measurement point on the substrate, Ctr indicates the substrate center position, R / 2 indicates a position that is half the substrate radius from the substrate center, and Edge indicates the substrate peripheral position. The vertical axis indicates the resistivity. When RRG was computed from this result, it was RRG = 56.6%.
次に、前記作製したシリコン単結晶基板にドライ酸素雰囲気下で１２００℃、１００分の熱処理を行った後、面内の抵抗率分布を測定した。図６はこのようにして測定した面内抵抗率分布を示すグラフである。この測定結果からＲＲＧを算出したところ、ＲＲＧ＝１３．６％であった。この後シリコン単結晶基板に試験的に６００〜１３００℃の熱処理を行ったが、ＲＲＧは１３．６％からほとんど変化しなかった。この結果から、このシリコン単結晶基板のＲＲＧの保証値を１３．６％とした。 Next, the manufactured silicon single crystal substrate was heat-treated at 1200 ° C. for 100 minutes in a dry oxygen atmosphere, and then the in-plane resistivity distribution was measured. FIG. 6 is a graph showing the in-plane resistivity distribution measured in this manner. When RRG was computed from this measurement result, it was RRG = 13.6%. Thereafter, the silicon single crystal substrate was experimentally heat-treated at 600 to 1300 ° C., but the RRG hardly changed from 13.6%. From this result, the guaranteed value of RRG of this silicon single crystal substrate was set to 13.6%.
直径１２５ｍｍのＮ型シリコン単結晶インゴットをＦＺ法により育成し、育成中に窒素ガスにより窒素を添加した。そして該育成したシリコン単結晶インゴットをスライス切断して面方位｛１１１｝のシリコン単結晶基板を作製した。このようにしてＮ型シリコン単結晶基板を１０００〜１１０００Ω・ｃｍの様々な抵抗率で４８枚だけ作製した。このように作製したシリコン単結晶基板各々の面内の平均抵抗率及びＲＲＧを測定し、これらのシリコン単結晶基板にドライ酸素雰囲気下で１２００℃、１００分の熱処理を行い、その後に再び面内の平均抵抗率及びＲＲＧを測定した。 An N-type silicon single crystal ingot having a diameter of 125 mm was grown by the FZ method, and nitrogen was added by nitrogen gas during the growth. Then, the grown silicon single crystal ingot was sliced to produce a silicon single crystal substrate having a plane orientation of {111}. In this way, only 48 N-type silicon single crystal substrates were produced with various resistivity of 1000 to 11000 Ω · cm. The in-plane average resistivity and RRG of each of the silicon single crystal substrates thus fabricated were measured, and these silicon single crystal substrates were heat-treated at 1200 ° C. for 100 minutes in a dry oxygen atmosphere, and then again in-plane. The average resistivity and RRG were measured.
図７は、前記作製したシリコン単結晶基板の内の４つのサンプルＡ、Ｂ、Ｃ、Ｄについて、熱処理前後の面内抵抗率分布を示すグラフである。いずれも横軸は測定点の基板上の位置を示し、縦軸は抵抗率を示す。いずれのサンプルにおいても、熱処理により窒素のドナー作用が消去し、面内抵抗率の上昇及びＲＲＧの降下が観測された。例えば熱処理前の平均抵抗率が５７００Ω・ｃｍであるサンプルＡに関しては、熱処理前のＲＲＧが３８．８％であったのに対して、熱処理後のＲＲＧは１９．６％であり、熱処理によるＲＲＧの変化量が１９．２％であった。すなわち、サンプルＡに対して本発明に従って熱処理をしなければ、後工程である半導体素子製造工程において工程中の熱処理によりＲＲＧが１９．２％も変化してしまう可能性があるが、本発明に従ってサンプルＡにドライ酸素雰囲気下で１２００℃、１００分の熱処理を行い、その後測定したＲＲＧをサンプルＡのＲＲＧ保証値にすることにより、半導体素子製造工程により変化しないとともに、十分に小さな値のＲＲＧを保証値とすることができる。 FIG. 7 is a graph showing the in-plane resistivity distribution before and after the heat treatment for four samples A, B, C, and D of the produced silicon single crystal substrate. In either case, the horizontal axis indicates the position of the measurement point on the substrate, and the vertical axis indicates the resistivity. In any sample, the donor effect of nitrogen was eliminated by the heat treatment, and an increase in in-plane resistivity and a decrease in RRG were observed. For example, for sample A having an average resistivity before heat treatment of 5700 Ω · cm, the RRG before heat treatment was 38.8%, whereas the RRG after heat treatment was 19.6%. The amount of change was 19.2%. That is, if the sample A is not heat-treated according to the present invention, the RRG may be changed by 19.2% due to the heat treatment during the process in the semiconductor element manufacturing process which is a subsequent process. Sample A is subjected to heat treatment at 1200 ° C. for 100 minutes in a dry oxygen atmosphere, and then the measured RRG is set to the RRG guaranteed value of Sample A, so that it does not change depending on the semiconductor element manufacturing process, and a sufficiently small value of RRG is obtained. It can be a guaranteed value.
図８は前記作製したシリコン単結晶基板の熱処理前の面内平均抵抗率に対する、熱処理後のＲＲＧの変化、すなわち当該シリコン単結晶基板の熱処理前のＲＲＧと熱処理後のＲＲＧの差を示すグラフである。縦軸の負の値は熱処理後にＲＲＧが小さくなったことを示す。図８に示すように、熱処理前の面内平均抵抗率が高くなるほど熱処理後のＲＲＧの変化が大きかった。図８には比較のため、面内平均抵抗率１０００Ω・ｃｍ未満の場合のデータも合わせてプロットしたが、これを見ると、１０００Ω・ｃｍ未満であれば、熱処理前後でそれ程ＲＲＧの変化は大きくないが、１０００Ω・ｃｍ以上ではＲＲＧの変化が大きくなり、熱処理が必要であることが判る。特に３０００Ω・ｃｍ以上では１０％以上変化する可能性がある。従って、本発明に従って、９００〜１２５０℃の温度で１０〜１２０分の熱処理を行った後にＲＲＧを測定すれば、平均抵抗率１０００Ω・ｃｍ以上の高抵抗率のシリコン単結晶基板であっても、面内抵抗率分布の保証がより正確で信頼度が高いものとなる。また、本発明の効果は、平均抵抗率が高ければ高いほど顕著になる。
以上、実施例１〜４で育成したシリコン単結晶インゴットの窒素濃度はいずれも４×１０１４〜１×１０１５ａｔｏｍｓ／ｃｍ３の間にあることをＦＴＩＲ（フーリエ変換赤外分光光度計）装置により確認された。FIG. 8 is a graph showing the change in RRG after the heat treatment relative to the in-plane average resistivity of the manufactured silicon single crystal substrate before the heat treatment, that is, the difference between the RRG before the heat treatment of the silicon single crystal substrate and the RRG after the heat treatment. is there. A negative value on the vertical axis indicates that RRG has decreased after heat treatment. As shown in FIG. 8, the change in RRG after the heat treatment increases as the in-plane average resistivity before the heat treatment increases. For comparison, FIG. 8 also plots data in the case where the in-plane average resistivity is less than 1000 Ω · cm. When this is seen, if it is less than 1000 Ω · cm, the change in RRG is so large before and after the heat treatment. Although it is not, the change of RRG becomes large at 1000 Ω · cm or more, and it can be seen that heat treatment is necessary. In particular, at 3000 Ω · cm or more, there is a possibility of a change of 10% or more. Therefore, according to the present invention, if RRG is measured after heat treatment at 900 to 1250 ° C. for 10 to 120 minutes, even if it is a silicon single crystal substrate having a high resistivity with an average resistivity of 1000 Ω · cm or more, The guarantee of the in-plane resistivity distribution is more accurate and reliable. Further, the effect of the present invention becomes more prominent as the average resistivity is higher.
As described above, the FTIR (Fourier Transform Infrared Spectrophotometer) apparatus indicates that the nitrogen concentrations of the silicon single crystal ingots grown in Examples 1 to 4 are all between 4 × 10 14 to 1 × 10 15 atoms / cm 3. Confirmed by
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、実施例では面方位｛１１１｝のシリコン単結晶基板を製造したが、面方位は｛１００｝、｛１１０｝であってもよいし、これらの面方位から傾斜させた面方位をもつものであってもよい。基板の直径は１００ｍｍ未満であってもよいし、１２５ｍｍ、１５０ｍｍまたはそれ以上であってもよい。前述のように、基板の直径が大きいほど面内抵抗率分布の不均一性が大きくなるので、本発明が効果的となる。また、実施例の窒素によるドナー濃度は５ｐｐｔａ（＝２．５×１０１１ａｔｏｍｓ／ｃｍ３）であったが、５ｐｐｔａ以下となる場合であっても、１０００Ω・ｃｍ以上という、熱処理前後で抵抗率が大きく変化するような高い抵抗率のシリコン単結晶基板であれば、本発明の効果は高いものとなる。またこれ以上の窒素ドナー濃度になるような場合であれば熱処理前後の抵抗率の乖離がさらに大きくなるので、本発明の効果はさらに高いものとなる。For example, in the examples, a silicon single crystal substrate having a plane orientation {111} was manufactured, but the plane orientation may be {100}, {110}, or having a plane orientation inclined from these plane orientations. It may be. The diameter of the substrate may be less than 100 mm, 125 mm, 150 mm or more. As described above, since the non-uniformity of the in-plane resistivity distribution increases as the substrate diameter increases, the present invention is effective. In addition, the donor concentration by nitrogen of the example was 5 ppta (= 2.5 × 10 11 atoms / cm 3 ), but even when it was 5 ppta or less, the resistivity before and after heat treatment was 1000 Ω · cm or more. If the silicon single crystal substrate has a high resistivity so that the resistance changes greatly, the effect of the present invention is high. If the nitrogen donor concentration is higher than this, the difference in resistivity before and after the heat treatment is further increased, and the effect of the present invention is further enhanced.
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| PCT/JP2004/010489 WO2005010243A1 (en) | 2003-07-29 | 2004-07-23 | Process for producing silicon single crystal substrate, method of measuring resistance characteristics and method of warranting resistance characteristics |
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| JP2007176725A (en) * | 2005-12-27 | 2007-07-12 | Shin Etsu Handotai Co Ltd | Method for manufacturing neutron-irradiated silicon single crystal |
| JP5070737B2 (en) * | 2006-05-26 | 2012-11-14 | 信越半導体株式会社 | Method for producing FZ single crystal silicon using silicon crystal rod produced by CZ method as raw material |
| JP5477188B2 (en) * | 2010-06-18 | 2014-04-23 | 信越半導体株式会社 | Silicon wafer PN determination method |
| JP6601057B2 (en) * | 2015-08-26 | 2019-11-06 | 株式会社Ｓｕｍｃｏ | Method for producing n-type silicon single crystal ingot and method for producing n-type silicon wafer |
| JP6471683B2 (en) * | 2015-12-07 | 2019-02-20 | 株式会社Sumco | Method for producing silicon single crystal |
| EP3208366A1 (en) * | 2016-02-16 | 2017-08-23 | Siltronic AG | Fz silicon and method to prepare fz silicon |
| EP3469120B1 (en) | 2016-06-08 | 2022-02-02 | GlobalWafers Co., Ltd. | High resistivity single crystal silicon ingot and wafer having improved mechanical strength |
| JP6954088B2 (en) * | 2017-12-19 | 2021-10-27 | 株式会社Sumco | Method for manufacturing silicon single crystal |
| JP6809568B2 (en) * | 2019-06-26 | 2021-01-06 | 株式会社Sumco | Manufacturing method of n-type silicon single crystal ingot and manufacturing method of n-type silicon wafer |
| JP7173082B2 (en) * | 2020-04-17 | 2022-11-16 | 信越半導体株式会社 | Silicon single crystal substrate for vapor phase epitaxy, vapor phase epitaxy substrate, and manufacturing method thereof |
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| JP4463957B2 (en) * | 2000-09-20 | 2010-05-19 | 信越半導体株式会社 | Silicon wafer manufacturing method and silicon wafer |
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