WO2018105192A1 - Production method for monocrystalline silicon - Google Patents
Production method for monocrystalline silicon Download PDFInfo
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- WO2018105192A1 WO2018105192A1 PCT/JP2017/033226 JP2017033226W WO2018105192A1 WO 2018105192 A1 WO2018105192 A1 WO 2018105192A1 JP 2017033226 W JP2017033226 W JP 2017033226W WO 2018105192 A1 WO2018105192 A1 WO 2018105192A1
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- 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
- C30B15/00—Single-crystal growth by pulling from a melt, e.g. Czochralski method
- C30B15/20—Controlling or regulating
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- 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
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/02—Elements
- C30B29/06—Silicon
Definitions
- the present invention relates to a method for manufacturing a silicon single crystal, and more particularly to a method for manufacturing a silicon single crystal having a high resistivity of 1000 ⁇ cm or more.
- a silicon single crystal having a target resistivity is manufactured by adding a dopant such as phosphorus or boron to a silicon raw material.
- the purity of polycrystalline silicon generally guarantees the donor concentration and acceptor concentration in the bulk part. This is because the polycrystalline silicon used for the FZ method is hollowed out from the manufactured polycrystalline silicon rod, and the donor concentration and acceptor concentration in the bulk part are measured. Using this as a raw material, a silicon single crystal is obtained by the FZ method.
- the sample (hereinafter referred to as the FZ sample) that was manufactured and cut out from the silicon single crystal thus manufactured has a donor or acceptor concentration in the bulk portion of the polycrystalline silicon that is below the standard value, Guaranteed by resistivity above a certain value.
- any value of resistivity was acceptable as long as the resistivity was 1000 ⁇ cm or more.
- recent quality requirements include, for example, the requirement that the resistivity is 1000 ⁇ cm or more, the conductivity type is P-type, N-type conductivity type is specified, the upper limit of the resistivity is limited to 1000 to 3000 ⁇ cm, the conductivity type is P-type or N-type conductivity type, and the resistivity is further required to be 5000 ⁇ cm or more.
- Patent Document 1 As a method for producing such a high resistivity silicon single crystal, in Patent Document 1, in addition to the donor concentration and acceptor concentration (or resistivity) of the bulk portion of polycrystalline silicon, the donor concentration and the surface portion of polycrystalline silicon A method has been proposed in which the acceptor concentration (or resistivity) is measured, the amount of the dopant is determined based on the measurement result, and a high resistivity silicon single crystal is manufactured.
- Patent Document 1 has a problem in that when the resistivity of the silicon single crystal becomes a high resistivity of 1000 ⁇ cm or more, variation occurs with respect to the target resistivity (that is, the accuracy deteriorates).
- the present invention has been made in order to solve the above-described problem, and a silicon single crystal capable of accurately producing a silicon single crystal having a desired resistivity even if it is a silicon single crystal having a high resistivity of 1000 ⁇ cm or more. It aims at providing the manufacturing method of.
- the present invention is a method for producing a silicon single crystal having a high resistivity of 1000 ⁇ cm or more by the CZ method, which is based on the impurity concentration of the surface and the bulk portion of polycrystalline silicon as a raw material in advance.
- the difference between the resistivity and the target resistivity of the silicon single crystal produced by adjusting the amount of the doped dopant is defined, and this difference is defined as the influence of the amount of environmental pollution.
- a method for producing a silicon single crystal wherein a silicon single crystal is produced by adjusting the amount of the dopant added so as to offset the amount of environmental contamination based on the impurity concentration of the material and the amount of environmental contamination.
- Such a silicon single crystal manufacturing method can accurately manufacture a silicon single crystal having a desired resistivity even if it is a silicon single crystal having a high resistivity of 1000 ⁇ cm or more.
- the adjustment of the amount of the doping agent that offsets the amount of environmental pollution is performed when the influence amount of the donor concentration or acceptor concentration of the environmental contamination amount exceeds a predetermined range with respect to the target resistivity. Is preferred.
- a silicon single crystal can be manufactured with higher accuracy with respect to the target resistivity.
- a silicon single crystal having a resistivity of 6000 ⁇ cm or more as the silicon single crystal is preferable to manufacture a silicon single crystal having a resistivity of 6000 ⁇ cm or more as the silicon single crystal.
- the silicon single crystal manufacturing method of the present invention can accurately manufacture a silicon single crystal having a narrow resistivity standard even when the resistivity of the silicon single crystal to be manufactured is 6000 ⁇ cm or more.
- the silicon single crystal manufacturing method of the present invention can accurately manufacture a silicon single crystal having a desired resistivity even if it is a silicon single crystal having a high resistivity of 1000 ⁇ cm or more. . Further, even when the resistivity of the silicon single crystal to be manufactured is 3000 ⁇ cm or more, or 6000 ⁇ cm or more, a silicon single crystal having a narrow resistivity standard can be manufactured with high accuracy. In addition, even in a manufacturing environment with different amounts of environmental pollution, a silicon single crystal having a high resistivity of 1000 ⁇ cm or more can be accurately manufactured.
- 6 is a histogram showing a deviation amount with respect to a target resistivity and its variation when a silicon single crystal is manufactured with a target resistivity of P-type 1000 to 3000 ⁇ cm in Example 1 and Comparative Example 1.
- 6 is a histogram showing a deviation amount and variation with respect to a target resistivity when a silicon single crystal is manufactured with a target resistivity of P-type 6000 ⁇ cm in Example 1 and Comparative Example 1.
- Example 2 and Comparative Example 2 when a silicon single crystal is manufactured with a target resistivity of P-type 1000 to 3000 ⁇ cm, the ratio of the donor concentration to the acceptor concentration and the actual resistivity of the manufactured silicon single crystal are shown. .
- Example 2 and Comparative Example 2 it is a graph which shows the ratio of a donor density
- Example 2 and Comparative Example 2 it is a graph which shows the ratio of a donor density
- the present inventors considered that there is a cause of variation in the resistivity of the manufactured silicon single crystal in addition to the impurity concentration of the surface or bulk part of the polycrystalline silicon used as a raw material, or the amount of doping agent introduced. .
- the present inventors consider not only the impurity concentration of the polycrystalline silicon surface and the bulk portion considered in the conventional method, but also the environmental influence (ie, the influence of the amount of environmental pollution) necessary for single crystal production. Then, it was found that a silicon single crystal having a desired resistivity can be produced with high precision by adjusting the amount of the dope added, and the present invention was completed.
- the present invention is a method for producing a silicon single crystal having a high resistivity of 1000 ⁇ cm or more by the CZ method, and the amount of doping agent introduced based on the impurity concentration of the surface and bulk portion of polycrystalline silicon as a raw material in advance.
- the difference between the resistivity of the silicon single crystal manufactured by adjusting the target and the target resistivity is obtained, and this difference is defined as the influence of the amount of environmental contamination.
- the impurity concentration of the surface and bulk portion of the polycrystalline silicon and the environment This is a silicon single crystal manufacturing method for manufacturing a silicon single crystal by adjusting the amount of the dopant added so as to offset the amount of environmental pollution based on the amount of contamination.
- FIG. 1 is a flowchart showing an example of a method for producing a silicon single crystal according to the present invention.
- the method for producing a silicon single crystal of FIG. 1 first, polycrystalline silicon as a raw material is prepared (FIG. 1 (1)), and the impurity concentration of the surface portion of the polycrystalline silicon and the impurity concentration of the bulk portion of the polycrystalline silicon. Is measured (FIGS. 1 (2) and (3)).
- the doping amount of the dopant is adjusted based on the measured impurity concentration of the surface and bulk portion of the polycrystalline silicon to produce a silicon single crystal (FIG. 1 (4)), and the resistance of the produced silicon single crystal.
- the rate is measured (FIG. 1 (5)).
- the difference between the measured resistivity and the target resistivity is obtained, this difference is defined as the influence of the amount of environmental pollution (FIG. 1 (6)), and the impurity concentration on the surface of the measured polycrystalline silicon and the bulk portion is measured.
- the input amount of the dopant is adjusted so as to offset the amount of environmental pollution (FIG. 1 (7)).
- a silicon single crystal is manufactured by introducing an adjusted amount of dopant into the polycrystalline silicon (FIG. 1 (8)), and the resistivity of the silicon single crystal thus manufactured is measured (FIG. 1 (FIG. 1)). 9)).
- the resistivity measured in this way is used as “the resistivity of the silicon single crystal manufactured in advance” at the next manufacturing, and the next manufacturing is shown in FIG. You may start from the step 6).
- polycrystalline silicon as a raw material is extracted by sampling a certain amount from a specific bag, and this certain amount of polycrystalline silicon is put in a hydrofluoric acid solution.
- a hydrofluoric acid solution in which the surface portion of the polycrystalline silicon is dissolved is put into an ICP-MS (inductively coupled plasma mass spectrometer), and quantitative analysis of dopant elements (for example, phosphorus, boron, etc.) is performed.
- the concentration of the dopant element is calculated on the assumption that the amount of the dopant element obtained by the quantitative analysis is included in the fixed amount of polycrystalline silicon.
- the dopant element is an N-type dopant such as phosphorus
- the donor concentration is used.
- the dopant element is a P-type dopant such as boron
- the acceptor concentration is used.
- said measuring method is an example and a measuring method is not limited to this.
- polycrystalline silicon as a raw material is extracted from a specific bag by sampling, the polycrystalline silicon is pulverized, and a certain amount of polycrystalline silicon in the central portion is collected.
- the surface portion of the certain amount of polycrystalline silicon is etched with hydrofluoric acid.
- all of the polycrystalline silicon from which the surface portion has been removed is dissolved with hydrofluoric acid.
- hydrofluoric acid in which polycrystalline silicon is dissolved is introduced into the ICP-MS, and quantitative analysis of dopant elements (for example, phosphorus, boron, etc.) is performed.
- the concentration of the dopant element is calculated on the assumption that the amount of the dopant element obtained by the quantitative analysis is included in the fixed amount of polycrystalline silicon.
- the dopant element is an N-type dopant such as phosphorus
- the donor concentration is used.
- the dopant element is a P-type dopant such as boron
- the acceptor concentration is used.
- said measuring method is an example and a measuring method is not limited to this.
- the carrier concentration A required for the target resistivity is calculated.
- the donor concentration contribution of the measured bulk portion of the polysilicon is added to the contribution of the donor concentration of the measured surface portion of the polycrystalline silicon to calculate the donor concentration B of the surface of the polycrystalline silicon and the bulk portion.
- the acceptor concentration C of the surface and the bulk part of the polycrystalline silicon is calculated. To do.
- the net carrier concentration becomes the carrier concentration A required for the target resistivity.
- the input amount D of the dopant is calculated.
- an acceptor concentration (carrier concentration A) of 0.2 ppba is required.
- a silicon single crystal is produced in advance by introducing a dopant in an amount calculated based on the impurity concentration of the surface and bulk portion of polycrystalline silicon as described above. Then, the resistivity of the silicon single crystal thus manufactured in advance is measured, and the difference between the measured resistivity and the target resistivity is obtained.
- the “resistivity of a silicon single crystal manufactured in advance” here does not have to be the resistivity of a silicon single crystal manufactured separately only for that purpose, and may be an actual resistivity at the time of previous manufacturing.
- the difference between the resistivity and the target resistivity of the silicon single crystal produced in advance as described above is defined as the influence of the amount of environmental pollution.
- the surface of polycrystalline silicon under the same environment is considered to be equally contaminated.
- the “environment” referred to here is an environment necessary for manufacturing a single crystal (for example, a storage place of polycrystalline silicon or a manufacturing room / manufacturing apparatus for manufacturing a single crystal), and more specifically, It includes a quartz crucible, a recharge tube, a pulling chamber, etc. with which the surface of polycrystalline silicon contacts.
- the amount of environment B / P can be obtained by calculating backward from the difference between the resistivity of the silicon single crystal produced in advance and the target resistivity.
- the environment level can be grasped by calculating back the environment B / P amount at the event related to the environment B / P amount.
- a specific back-calculation method of the environmental B / P amount for example, when the filter of a clean room is replaced, or when the storage location of a polycrystalline silicon, a quartz crucible, a recharge tube, etc. is changed, the actual resistance in a certain period An average value of the difference between the actual resistivity and the target resistivity is obtained from the rate transition, and the environmental B / P amount is calculated backward from this.
- the environmental B amount can be calculated, and when the P-type resistivity is high, the environmental P amount can be calculated back.
- a dopant is used so as to offset the amount of environmental B / P based on the impurity concentration of the surface and bulk portion of the polycrystalline silicon obtained as described above and the amount of environmental B / P.
- the silicon single crystal is manufactured by adjusting the amount of the silicon.
- Adjustment of the dope amount at this time is performed by, for example, creating a calculation sheet for determining the dope amount by inputting the impurity concentration of the surface and bulk portion of the polycrystalline silicon and the amount of environment B / P. This can be done by a method of determining the amount of the agent to be charged. In addition, using the same calculation sheet from the measurement result of the resistivity of the manufactured silicon single crystal, it is possible to reversely calculate the amount of environmental B / P and grasp the level. As a specific calculation method of the amount of the dopant, for example, by using the goal seek function incorporated in the spreadsheet software, the environmental B / P amount is calculated from the average value of the difference between the actual resistivity and the target resistivity. Can be calculated and the amount of dopant added can be calculated.
- the amount of the dope added is adjusted by such a method, even when the environment is different, by adjusting the concentration according to the environment, silicon having an equivalent resistivity is obtained.
- Single crystals can be produced. That is, even when the environment changes, a silicon single crystal having a desired resistivity can be manufactured with high accuracy.
- the adjustment of the amount of the doping agent that offsets the amount of environmental pollution is preferably performed when the influence amount of the donor concentration or acceptor concentration of the environmental contamination amount exceeds a predetermined range with respect to the target resistivity. More specifically, when the resistivity of the silicon single crystal produced in advance is shifted by approximately ⁇ 5% or more from the target resistivity due to the influence of the environmental B / P amount, the amount of dope added should be adjusted. Is preferred. In this way, by adjusting the amount of the dope added to offset the amount of environmental pollution, the accuracy with respect to the target resistivity can be further improved.
- the silicon single crystal manufacturing method of the present invention can accurately manufacture a silicon single crystal having a desired resistivity even if it is a silicon single crystal having a high resistivity of 1000 ⁇ cm or more. . Further, even when the resistivity of the silicon single crystal to be manufactured is 3000 ⁇ cm or more, or 6000 ⁇ cm or more, a silicon single crystal having a narrow resistivity standard can be manufactured with high accuracy. In addition, even in a manufacturing environment with different amounts of environmental pollution, a silicon single crystal having a high resistivity of 1000 ⁇ cm or more can be accurately manufactured. In addition, the resistivity of the silicon single crystal produced by the present invention is 1000 ⁇ cm or more, and the upper limit is not particularly limited. For example, by setting the resistivity to 30000 ⁇ cm or less, it is possible to produce a silicon single crystal having a narrow resistivity standard more accurately. it can.
- the polycrystalline silicon is charged with the doping amount obtained, and a silicon single crystal having a diameter of 200 mm is actually manufactured using a quartz crucible having a diameter of 600 mm (24 inches), and the resistivity of the manufactured silicon single crystal ( Actual resistivity) was measured.
- the measured resistivity was P-type of about 2800 ⁇ cm, and the deviation from the target resistivity was about + 12%.
- FIG. 4 shows the amount of deviation with respect to the target resistivity and its variation.
- Example 1 Based on FIG. 2, the difference between the actual resistivity and the target resistivity (calculated resistivity) of the silicon single crystal manufactured in Comparative Example 1 is obtained, and this difference is calculated as the amount of environmental pollution (environmental B / P amount in environment 1). From this difference, the amount of environment B was calculated back to 0.01 ppba. Next, in addition to the donor concentration and acceptor concentration of the surface and bulk portion of the polycrystalline silicon measured as described above, the target resistivity P-type 2500 ⁇ cm in consideration of the environment B amount obtained as described above. Then, the amount of the dope added so as to offset the amount of environmental pollution was determined.
- a doping agent is added in the amount required for polycrystalline silicon, a silicon single crystal having a diameter of 200 mm is manufactured using a quartz crucible having a diameter of 600 mm (24 inches), and the resistivity of the manufactured silicon single crystal ( Actual resistivity) was measured.
- the measured resistivity was about 2600 ⁇ cm P-type, and the deviation from the target resistivity was + 4%.
- FIG. 3 shows the relationship between the calculated resistivity (target resistivity) [x-axis] and the actual resistivity [y-axis] of the manufactured silicon single crystal.
- the silicon single crystal is manufactured with a target resistivity of P-type 1000 to 3000 ⁇ cm
- the amount of deviation with respect to the target resistivity and its variation are shown in FIG. 4, and when the silicon single crystal is manufactured with the target resistivity of P-type 6000 ⁇ cm,
- FIG. 5 shows the amount of deviation with respect to the target resistivity and its variation.
- Example 1 in which the silicon single crystal was manufactured by the manufacturing method of the present invention in consideration of the environmental B / P amount, the surface and bulk of the polycrystalline silicon including the environmental B / P amount were obtained. As a result of calculating the dose of the dopant from the impurity concentration of the portion, it was confirmed that the results were close to the calculated resistivity of the silicon single crystal at any target resistivity. On the other hand, in Comparative Example 1 in which a silicon single crystal was manufactured by a conventional manufacturing method that does not consider the environmental B / P amount, the calculated resistivity was often higher than the actual resistivity.
- Example 1 in which a silicon single crystal was manufactured by the manufacturing method of the present invention in consideration of the amount of environmental B / P, any one of the target resistivity P-type 1000 to 3000 ⁇ cm and 6000 ⁇ cm was obtained. Even in this case, compared to Comparative Example 1 in which a silicon single crystal is manufactured by a conventional manufacturing method that does not consider the amount of environmental B / P, the actual resistivity shift amount with respect to the target resistivity is small, and silicon having a desired resistivity is obtained. Single crystals could be manufactured with high accuracy. In particular, the improvement in accuracy with respect to the target resistivity at a high resistivity was remarkable.
- Example 2 Using polycrystalline silicon stored in two environments (environment 1 and environment 2) where the environment-derived acceptor concentration is environment 1> environment 2 (that is, acceptor dope concentration is environment 1> environment 2) Similarly to Example 1, a silicon single crystal was manufactured with a resistivity P-type of 1000 to 3000 ⁇ cm, 6000 ⁇ cm, and more than 10000 ⁇ cm without considering the amount of environment B / P, and the resistivity of the manufactured silicon single crystal was measured. Further, the ratio of the acceptor concentration derived from the environment to the bulk / surface of polycrystalline silicon and the acceptor derived from the dopant when the donor concentration ratio was set to 1 was determined. The results are shown in FIGS.
- Example 2 Using polycrystalline silicon stored in the same two kinds of environments (environments 1 and 2) as described above, the resistivity P-type 1000 to 3000 ⁇ cm, 6000 ⁇ cm, A silicon single crystal was produced at a thickness exceeding 10,000 ⁇ cm, and the resistivity of the produced silicon single crystal was measured. Further, the ratio of the acceptor concentration derived from the environment to the bulk / surface of polycrystalline silicon and the acceptor derived from the dopant when the donor concentration ratio was set to 1 was determined. The results are shown in FIGS.
- Example 2 in which a silicon single crystal was manufactured by the manufacturing method of the present invention in consideration of the amount of environmental B / P, the actual resistivity was measured in environments 1 and 2 at any target resistivity. There was almost no difference in resistivity, and the accuracy with respect to the target resistivity was good.
- Comparative Example 2 in which the silicon single crystal was manufactured by the conventional manufacturing method that does not consider the amount of environment B / P, there is a difference in the actual resistivity in environments 1 and 2 at any target resistivity. There was a big difference especially when the target resistivity was high.
- Comparative Example 2 when a silicon single crystal is manufactured using polycrystalline silicon stored in environment 1 having a higher acceptor concentration, the actual resistance is higher than in the case of using polycrystalline silicon stored in environment 2. The rate tended to be low. Moreover, in the comparative example 2, the precision with respect to the target resistivity was also inferior compared with the example 2. From this, if it is a manufacturing method of this invention, even if environmental B / P amount changes, environmental B / P amount will be grasped, and dope amount calculation in consideration of it will improve the accuracy to the target resistivity. was shown to be possible.
- the present invention is not limited to the above embodiment.
- the above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.
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Abstract
The present invention provides a method for producing a monocrystalline silicon having a resistivity of as high as 1000 Ωcm or more using the CZ process, the method being characterized in that a monocrystalline silicon is produced by calculating, in advance, the difference between a desired resistivity and the resistivity of a monocrystalline silicon produced by adjusting the added amount of a doping agent on the basis of the concentration of impurities in the bulk portions and surface of a polycrystalline silicon which is a raw material, defining the difference as the influence of an environmental contamination amount, and adjusting the added amount of the doping agent so as to cancel the environmental contamination amount, on the basis of the environmental contamination amount and the concentration of impurities in the bulk portions and surface of the polycrystalline silicon. As a result, provided is a monocrystalline silicon production method capable of highly accurately producing a monocrystalline silicon which has a resistivity of as high as 1000 Ωcm or more, but has a desired resistivity.
Description
本発明は、シリコン単結晶の製造方法に関し、特に、１０００Ωｃｍ以上の高抵抗率のシリコン単結晶の製造方法に関する。
The present invention relates to a method for manufacturing a silicon single crystal, and more particularly to a method for manufacturing a silicon single crystal having a high resistivity of 1000 Ωcm or more.
近年、ＣＺ法（チョクラルスキー法）によって製造されたシリコン単結晶の品質として、１０００Ωｃｍ以上の高抵抗率をもったものの要求が増えてきている。これらの用途としては、今までＦＺ法（フローティングゾーン法）によって製造されたシリコン単結晶で製造していた品種やＲＦデバイスといわれる通信用のデバイスなど、様々な用途がある。
In recent years, as a quality of a silicon single crystal manufactured by the CZ method (Czochralski method), there is an increasing demand for a material having a high resistivity of 1000 Ωcm or more. As these applications, there are various applications such as varieties manufactured using silicon single crystals manufactured by the FZ method (floating zone method) and communication devices called RF devices.
通常のＣＺ法による製造では、リンやボロンといったドープ剤をシリコン原料に添加することにより、目標の抵抗率をもったシリコン単結晶を製造している。
In the normal CZ method, a silicon single crystal having a target resistivity is manufactured by adding a dopant such as phosphorus or boron to a silicon raw material.
一方で、抵抗率１０００Ωｃｍ以上の高抵抗率のシリコン単結晶を製造する場合には、高純度の石英ルツボ（内表面が合成石英でコートされたもの）に高純度の多結晶シリコンを投入し、ドープ剤を添加しない方法、即ち、ノンドープで製造することが一般的である。
On the other hand, when manufacturing a high resistivity silicon single crystal having a resistivity of 1000 Ωcm or more, high purity polycrystalline silicon is introduced into a high purity quartz crucible (inner surface coated with synthetic quartz), In general, a method in which a dopant is not added, that is, non-doping is used.
多結晶シリコンの純度は、一般的にバルク部分のドナー濃度及びアクセプター濃度を品質保証している。これは、製造した多結晶シリコンのロッドから、ＦＺ法による製造に使われる多結晶シリコンをくりぬき、バルク部分のドナー濃度及びアクセプター濃度を測定するとともに、これを原料にしてＦＺ法によってシリコン単結晶を製造し、このようにして製造されたシリコン単結晶から切り出したサンプル（以下、ＦＺサンプルと称する）により、多結晶シリコンのバルク部分のドナー、アクセプターが規格値以下の濃度であること、ＦＺサンプルの抵抗率がある値以上であることにより保証している。上記で保証された多結晶シリコンを使うことにより、１０００Ωｃｍ以上の高抵抗率のシリコン単結晶を製造することが可能となる。
The purity of polycrystalline silicon generally guarantees the donor concentration and acceptor concentration in the bulk part. This is because the polycrystalline silicon used for the FZ method is hollowed out from the manufactured polycrystalline silicon rod, and the donor concentration and acceptor concentration in the bulk part are measured. Using this as a raw material, a silicon single crystal is obtained by the FZ method. The sample (hereinafter referred to as the FZ sample) that was manufactured and cut out from the silicon single crystal thus manufactured has a donor or acceptor concentration in the bulk portion of the polycrystalline silicon that is below the standard value, Guaranteed by resistivity above a certain value. By using the polycrystalline silicon guaranteed as described above, it becomes possible to manufacture a silicon single crystal having a high resistivity of 1000 Ωcm or more.
今までは、抵抗率が１０００Ωｃｍ以上であれば、どのような値の抵抗率でも良かったが、最近の品質要求は、例えば、抵抗率が１０００Ωｃｍ以上という要求に加えて、導電型がＰ型、Ｎ型の導電型指定であることや、抵抗率の上限を１０００～３０００Ωｃｍに限定されたり、導電型がＰ型、Ｎ型の導電型指定であって、更に抵抗率が５０００Ωｃｍ以上という要求がなされたりする。
Until now, any value of resistivity was acceptable as long as the resistivity was 1000 Ωcm or more. However, recent quality requirements include, for example, the requirement that the resistivity is 1000 Ωcm or more, the conductivity type is P-type, N-type conductivity type is specified, the upper limit of the resistivity is limited to 1000 to 3000 Ωcm, the conductivity type is P-type or N-type conductivity type, and the resistivity is further required to be 5000 Ωcm or more. Or
このような厳しい要求に対して、原料となる多結晶シリコンのドナー、アクセプターの量を的確に把握し、必要なドープ剤（例えば、ボロン）を添加する必要がある。
In response to such strict requirements, it is necessary to accurately grasp the amount of polycrystalline silicon donors and acceptors, and to add a necessary dopant (for example, boron).
このような高抵抗率シリコン単結晶の製造方法として、特許文献１では、多結晶シリコンのバルク部分のドナー濃度及びアクセプター濃度（あるいは抵抗率）に加えて、多結晶シリコンの表面部分のドナー濃度及びアクセプター濃度（あるいは抵抗率）を測定し、その測定結果に基づいてドープ剤の投入量を決定し、高抵抗率のシリコン単結晶を製造する方法が提案されている。
As a method for producing such a high resistivity silicon single crystal, in Patent Document 1, in addition to the donor concentration and acceptor concentration (or resistivity) of the bulk portion of polycrystalline silicon, the donor concentration and the surface portion of polycrystalline silicon A method has been proposed in which the acceptor concentration (or resistivity) is measured, the amount of the dopant is determined based on the measurement result, and a high resistivity silicon single crystal is manufactured.
しかしながら、特許文献１の製造方法では、シリコン単結晶の抵抗率が１０００Ωｃｍ以上の高抵抗率になると、狙い抵抗率に対してばらつきが発生する（即ち、精度が悪くなる）という問題があった。
However, the manufacturing method of Patent Document 1 has a problem in that when the resistivity of the silicon single crystal becomes a high resistivity of 1000 Ωcm or more, variation occurs with respect to the target resistivity (that is, the accuracy deteriorates).
また、最近では、１０００Ωｃｍ以上で導電型指定かつ抵抗率規格の狭い品質要求が増加していることから、１０００Ωｃｍ以上の高抵抗率であっても、所望の抵抗率を有するシリコン単結晶を精度よく製造できる方法の開発が求められていた。
Also, recently, the requirement for quality with a narrow conductivity type designation and resistivity standard at 1000 Ωcm or more is increasing, so even a high resistivity of 1000 Ωcm or more can accurately produce a silicon single crystal having a desired resistivity. There was a need to develop a method that could be manufactured.
本発明は、上記問題を解決するためになされたものであり、１０００Ωｃｍ以上の高抵抗率のシリコン単結晶であっても、所望の抵抗率を有するシリコン単結晶を精度よく製造可能なシリコン単結晶の製造方法を提供することを目的とする。
The present invention has been made in order to solve the above-described problem, and a silicon single crystal capable of accurately producing a silicon single crystal having a desired resistivity even if it is a silicon single crystal having a high resistivity of 1000 Ωcm or more. It aims at providing the manufacturing method of.
上記課題を達成するために、本発明では、ＣＺ法により１０００Ωｃｍ以上の高抵抗率のシリコン単結晶を製造する方法であって、予め原料となる多結晶シリコンの表面及びバルク部分の不純物濃度に基づいてドープ剤の投入量を調整して製造したシリコン単結晶の抵抗率と狙い抵抗率の差異を求め、この差異を環境汚染量の影響と定義し、次に前記多結晶シリコンの表面及びバルク部分の不純物濃度と前記環境汚染量に基づいて前記環境汚染量を相殺するように前記ドープ剤の投入量を調整してシリコン単結晶を製造するシリコン単結晶の製造方法を提供する。
In order to achieve the above object, the present invention is a method for producing a silicon single crystal having a high resistivity of 1000 Ωcm or more by the CZ method, which is based on the impurity concentration of the surface and the bulk portion of polycrystalline silicon as a raw material in advance. The difference between the resistivity and the target resistivity of the silicon single crystal produced by adjusting the amount of the doped dopant is defined, and this difference is defined as the influence of the amount of environmental pollution. There is provided a method for producing a silicon single crystal, wherein a silicon single crystal is produced by adjusting the amount of the dopant added so as to offset the amount of environmental contamination based on the impurity concentration of the material and the amount of environmental contamination.
このようなシリコン単結晶の製造方法であれば、１０００Ωｃｍ以上の高抵抗率のシリコン単結晶であっても、所望の抵抗率を有するシリコン単結晶を精度よく製造することができる。
Such a silicon single crystal manufacturing method can accurately manufacture a silicon single crystal having a desired resistivity even if it is a silicon single crystal having a high resistivity of 1000 Ωcm or more.
また、前記環境汚染量を相殺するドープ剤の投入量の調整は、前記環境汚染量のドナー濃度又はアクセプター濃度の影響量が、前記狙い抵抗率に対して所定の範囲を超えたときに行うことが好ましい。
Further, the adjustment of the amount of the doping agent that offsets the amount of environmental pollution is performed when the influence amount of the donor concentration or acceptor concentration of the environmental contamination amount exceeds a predetermined range with respect to the target resistivity. Is preferred.
このように環境汚染量を相殺するドープ剤の投入量の調整を行えば、狙い抵抗率に対して更に精度よくシリコン単結晶を製造することができる。
Thus, by adjusting the input amount of the dopant that offsets the amount of environmental pollution, a silicon single crystal can be manufactured with higher accuracy with respect to the target resistivity.
また、前記シリコン単結晶として、抵抗率６０００Ωｃｍ以上のシリコン単結晶を製造することが好ましい。
Moreover, it is preferable to manufacture a silicon single crystal having a resistivity of 6000 Ωcm or more as the silicon single crystal.
本発明のシリコン単結晶の製造方法であれば、製造するシリコン単結晶の抵抗率を６０００Ωｃｍ以上とした場合にも、抵抗率規格の狭いシリコン単結晶を精度よく製造することができる。
The silicon single crystal manufacturing method of the present invention can accurately manufacture a silicon single crystal having a narrow resistivity standard even when the resistivity of the silicon single crystal to be manufactured is 6000 Ωcm or more.
以上のように、本発明のシリコン単結晶の製造方法であれば、１０００Ωｃｍ以上の高抵抗率のシリコン単結晶であっても、所望の抵抗率を有するシリコン単結晶を精度よく製造することができる。また、製造するシリコン単結晶の抵抗率を３０００Ωｃｍ以上、あるいは６０００Ωｃｍ以上とした場合にも、抵抗率規格の狭いシリコン単結晶を精度よく製造することができる。また、環境汚染量の異なる製造環境であっても、１０００Ωｃｍ以上の高抵抗率のシリコン単結晶を精度よく製造することができる。
As described above, the silicon single crystal manufacturing method of the present invention can accurately manufacture a silicon single crystal having a desired resistivity even if it is a silicon single crystal having a high resistivity of 1000 Ωcm or more. . Further, even when the resistivity of the silicon single crystal to be manufactured is 3000 Ωcm or more, or 6000 Ωcm or more, a silicon single crystal having a narrow resistivity standard can be manufactured with high accuracy. In addition, even in a manufacturing environment with different amounts of environmental pollution, a silicon single crystal having a high resistivity of 1000 Ωcm or more can be accurately manufactured.
上述のように、１０００Ωｃｍ以上の高抵抗率であっても、所望の抵抗率を有するシリコン単結晶を精度よく製造できる方法の開発が求められていた。
As described above, there has been a demand for the development of a method capable of accurately producing a silicon single crystal having a desired resistivity even when the resistivity is 1000 Ωcm or higher.
本発明者らは、原料となる多結晶シリコンの表面やバルク部分の不純物濃度、あるいはドープ剤の投入量以外にも、製造されるシリコン単結晶の抵抗率にばらつきを生む原因があると考えた。この考えに基づいて調査したところ、単結晶製造に必要な環境（例えば、多結晶シリコンの保管場所や単結晶を製造する製造室・製造装置）の影響によって抵抗率にばらつきが発生していることが分かった。そこで、本発明者らは、従来法で考慮されていた多結晶シリコンの表面やバルク部分の不純物濃度に加えて、単結晶製造に必要な環境の影響（即ち、環境汚染量の影響）を考慮してドープ剤の投入量を調整することで、所望の抵抗率を有するシリコン単結晶を精度よく製造できることを見出し、本発明を完成させた。
The present inventors considered that there is a cause of variation in the resistivity of the manufactured silicon single crystal in addition to the impurity concentration of the surface or bulk part of the polycrystalline silicon used as a raw material, or the amount of doping agent introduced. . As a result of investigation based on this idea, there is a variation in resistivity due to the influence of the environment necessary for single crystal manufacturing (for example, the storage location of polycrystalline silicon and the manufacturing room / manufacturing equipment for manufacturing single crystals). I understood. Therefore, the present inventors consider not only the impurity concentration of the polycrystalline silicon surface and the bulk portion considered in the conventional method, but also the environmental influence (ie, the influence of the amount of environmental pollution) necessary for single crystal production. Then, it was found that a silicon single crystal having a desired resistivity can be produced with high precision by adjusting the amount of the dope added, and the present invention was completed.
即ち、本発明は、ＣＺ法により１０００Ωｃｍ以上の高抵抗率のシリコン単結晶を製造する方法であって、予め原料となる多結晶シリコンの表面及びバルク部分の不純物濃度に基づいてドープ剤の投入量を調整して製造したシリコン単結晶の抵抗率と狙い抵抗率の差異を求め、この差異を環境汚染量の影響と定義し、次に前記多結晶シリコンの表面及びバルク部分の不純物濃度と前記環境汚染量に基づいて前記環境汚染量を相殺するように前記ドープ剤の投入量を調整してシリコン単結晶を製造するシリコン単結晶の製造方法である。
That is, the present invention is a method for producing a silicon single crystal having a high resistivity of 1000 Ωcm or more by the CZ method, and the amount of doping agent introduced based on the impurity concentration of the surface and bulk portion of polycrystalline silicon as a raw material in advance. The difference between the resistivity of the silicon single crystal manufactured by adjusting the target and the target resistivity is obtained, and this difference is defined as the influence of the amount of environmental contamination. Next, the impurity concentration of the surface and bulk portion of the polycrystalline silicon and the environment This is a silicon single crystal manufacturing method for manufacturing a silicon single crystal by adjusting the amount of the dopant added so as to offset the amount of environmental pollution based on the amount of contamination.
以下、本発明について詳細に説明するが、本発明はこれらに限定されるものではない。
Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.
図１は、本発明のシリコン単結晶の製造方法の一例を示すフロー図である。図１のシリコン単結晶の製造方法では、まず、原料となる多結晶シリコンを準備し（図１（１））、多結晶シリコンの表面部分の不純物濃度と、多結晶シリコンのバルク部分の不純物濃度を測定する（図１（２）、（３））。次に、測定した多結晶シリコンの表面及びバルク部分の不純物濃度に基づいてドープ剤の投入量を調整して、シリコン単結晶を製造し（図１（４））、製造したシリコン単結晶の抵抗率を測定する（図１（５））。次に、測定した抵抗率と狙い抵抗率との差異を求め、この差異を環境汚染量の影響と定義して（図１（６））、測定した多結晶シリコンの表面及びバルク部分の不純物濃度と環境汚染量に基づいて環境汚染量を相殺するようにドープ剤の投入量を調整する（図１（７））。そして、多結晶シリコンに調整した投入量のドープ剤を投入してシリコン単結晶を製造し（図１（８））、このようにして製造したシリコン単結晶の抵抗率を測定する（図１（９））。なお、連続してシリコン単結晶の製造を行う場合には、このようにして測定した抵抗率を、次回製造時に「予め製造したシリコン単結晶の抵抗率」として利用し、次回製造を図１（６）の工程から開始してもよい。
FIG. 1 is a flowchart showing an example of a method for producing a silicon single crystal according to the present invention. In the method for producing a silicon single crystal of FIG. 1, first, polycrystalline silicon as a raw material is prepared (FIG. 1 (1)), and the impurity concentration of the surface portion of the polycrystalline silicon and the impurity concentration of the bulk portion of the polycrystalline silicon. Is measured (FIGS. 1 (2) and (3)). Next, the doping amount of the dopant is adjusted based on the measured impurity concentration of the surface and bulk portion of the polycrystalline silicon to produce a silicon single crystal (FIG. 1 (4)), and the resistance of the produced silicon single crystal. The rate is measured (FIG. 1 (5)). Next, the difference between the measured resistivity and the target resistivity is obtained, this difference is defined as the influence of the amount of environmental pollution (FIG. 1 (6)), and the impurity concentration on the surface of the measured polycrystalline silicon and the bulk portion is measured. Based on the amount of environmental pollution, the input amount of the dopant is adjusted so as to offset the amount of environmental pollution (FIG. 1 (7)). Then, a silicon single crystal is manufactured by introducing an adjusted amount of dopant into the polycrystalline silicon (FIG. 1 (8)), and the resistivity of the silicon single crystal thus manufactured is measured (FIG. 1 (FIG. 1)). 9)). When the silicon single crystal is continuously manufactured, the resistivity measured in this way is used as “the resistivity of the silicon single crystal manufactured in advance” at the next manufacturing, and the next manufacturing is shown in FIG. You may start from the step 6).
ここで、多結晶シリコンの表面部分の不純物濃度（より具体的には、ドナー濃度及びアクセプター濃度）の測定方法の一例について、以下に説明する。まず、原料となる多結晶シリコンを、特定の袋から一定量だけサンプリングにより抽出し、この一定量の多結晶シリコンをフッ酸溶液中にいれる。次いで、多結晶シリコンの表面部分が溶解した後に、残った多結晶シリコンをフッ酸溶液中から取り出す。次いで、多結晶シリコンの表面部分が溶解したフッ酸溶液をＩＣＰ－ＭＳ（誘導結合プラズマ質量分析装置）に投入して、ドーパント元素（例えば、リン、ボロン等）の定量分析を行う。次いで、定量分析によって得られた量のドーパント元素が、上記の一定量の多結晶シリコンに含まれると仮定して、ドーパント元素の濃度を算出する。ドーパント元素がリンのようなＮ型のドーパントの場合にはドナー濃度とし、ドーパント元素がボロンのようなＰ型のドーパントの場合にはアクセプター濃度とする。なお、上記の測定方法は一例であり、測定方法はこれに限定されない。
Here, an example of a method for measuring the impurity concentration (more specifically, the donor concentration and the acceptor concentration) of the surface portion of the polycrystalline silicon will be described below. First, polycrystalline silicon as a raw material is extracted by sampling a certain amount from a specific bag, and this certain amount of polycrystalline silicon is put in a hydrofluoric acid solution. Next, after the surface portion of the polycrystalline silicon is dissolved, the remaining polycrystalline silicon is taken out from the hydrofluoric acid solution. Next, a hydrofluoric acid solution in which the surface portion of the polycrystalline silicon is dissolved is put into an ICP-MS (inductively coupled plasma mass spectrometer), and quantitative analysis of dopant elements (for example, phosphorus, boron, etc.) is performed. Next, the concentration of the dopant element is calculated on the assumption that the amount of the dopant element obtained by the quantitative analysis is included in the fixed amount of polycrystalline silicon. When the dopant element is an N-type dopant such as phosphorus, the donor concentration is used. When the dopant element is a P-type dopant such as boron, the acceptor concentration is used. In addition, said measuring method is an example and a measuring method is not limited to this.
また、多結晶シリコンのバルク部分の不純物濃度（より具体的には、ドナー濃度及びアクセプター濃度）の測定方法の一例について、以下に説明する。まず、原料となる多結晶シリコンを、特定の袋からサンプリングにより抽出し、この多結晶シリコンを粉砕し、中心部分の多結晶シリコンを一定量採取する。次いで、この一定量の多結晶シリコンの表面部分を、フッ硝酸でエッチングする。次いで、表面部分が除去された多結晶シリコンをフッ硝酸ですべて溶解させる。次いで、多結晶シリコンが溶解したフッ硝酸をＩＣＰ－ＭＳに投入して、ドーパント元素（例えば、リン、ボロン等）の定量分析を行う。次いで、定量分析によって得られた量のドーパント元素が、上記の一定量の多結晶シリコンに含まれると仮定して、ドーパント元素の濃度を算出する。ドーパント元素がリンのようなＮ型のドーパントの場合にはドナー濃度とし、ドーパント元素がボロンのようなＰ型のドーパントの場合にはアクセプター濃度とする。なお、上記の測定方法は一例であり、測定方法はこれに限定されない。
In addition, an example of a method for measuring the impurity concentration (more specifically, the donor concentration and the acceptor concentration) in the bulk portion of the polycrystalline silicon will be described below. First, polycrystalline silicon as a raw material is extracted from a specific bag by sampling, the polycrystalline silicon is pulverized, and a certain amount of polycrystalline silicon in the central portion is collected. Next, the surface portion of the certain amount of polycrystalline silicon is etched with hydrofluoric acid. Next, all of the polycrystalline silicon from which the surface portion has been removed is dissolved with hydrofluoric acid. Next, hydrofluoric acid in which polycrystalline silicon is dissolved is introduced into the ICP-MS, and quantitative analysis of dopant elements (for example, phosphorus, boron, etc.) is performed. Next, the concentration of the dopant element is calculated on the assumption that the amount of the dopant element obtained by the quantitative analysis is included in the fixed amount of polycrystalline silicon. When the dopant element is an N-type dopant such as phosphorus, the donor concentration is used. When the dopant element is a P-type dopant such as boron, the acceptor concentration is used. In addition, said measuring method is an example and a measuring method is not limited to this.
また、シリコン単結晶を予め製造する際の、ドープ剤の投入量の決定方法について、以下に説明する。まず、狙い抵抗率（目標抵抗率）に必要なキャリア濃度Ａを計算する。次いで、測定した多結晶シリコンの表面部分のドナー濃度の寄与分に、測定した多結晶シリコンのバルク部分のドナー濃度の寄与分を加えて、多結晶シリコンの表面及びバルク部分のドナー濃度Ｂを算出する。次いで、測定した多結晶シリコンの表面部分のアクセプター濃度の寄与分に、測定した多結晶シリコンのバルク部分のアクセプター濃度の寄与分を加えて、多結晶シリコンの表面及びバルク部分のアクセプター濃度Ｃを算出する。次いで、多結晶シリコンの表面及びバルク部分のドナー濃度Ｂと、多結晶シリコンの表面及びバルク部分のアクセプター濃度Ｃを考慮して、正味のキャリア濃度が目標抵抗率に必要なキャリア濃度Ａになるように、ドープ剤の投入量Ｄを算出する。
Further, a method for determining the amount of the dope added when manufacturing the silicon single crystal in advance will be described below. First, the carrier concentration A required for the target resistivity (target resistivity) is calculated. Then, the donor concentration contribution of the measured bulk portion of the polysilicon is added to the contribution of the donor concentration of the measured surface portion of the polycrystalline silicon to calculate the donor concentration B of the surface of the polycrystalline silicon and the bulk portion. To do. Next, by adding the contribution of the acceptor concentration in the bulk part of the measured polycrystalline silicon to the contribution of the acceptor concentration in the surface part of the polycrystalline silicon, the acceptor concentration C of the surface and the bulk part of the polycrystalline silicon is calculated. To do. Next, considering the donor concentration B of the surface and bulk portion of the polycrystalline silicon and the acceptor concentration C of the surface and bulk portion of the polycrystalline silicon, the net carrier concentration becomes the carrier concentration A required for the target resistivity. In addition, the input amount D of the dopant is calculated.
例えば、導電型指定がＰ型で、狙い抵抗率が２０００Ωｃｍの場合には、０．２ｐｐｂａのアクセプター濃度（キャリア濃度Ａ）が必要となる。このとき、多結晶シリコンの表面及びバルク部分のドナー濃度Ｂが０．０２ｐｐｂａであり、多結晶シリコンの表面及びバルク部分のアクセプター濃度Ｃが、０．０５ｐｐｂａとすると、ドープ剤の投入量Ｄは、０．２ｐｐｂａ（キャリア濃度Ａ）－０．０５ｐｐｂａ（アクセプター濃度Ｃ）＋０．０２ｐｐｂａ（ドナー濃度Ｂ）＝０．１７ｐｐｂａと算出することができる。つまり、０．１７ｐｐｂａに相当する量のアクセプタードープ剤を投入すればよい。
For example, when the conductivity type designation is P type and the target resistivity is 2000 Ωcm, an acceptor concentration (carrier concentration A) of 0.2 ppba is required. At this time, when the donor concentration B of the surface and the bulk portion of the polycrystalline silicon is 0.02 ppba, and the acceptor concentration C of the surface and the bulk portion of the polycrystalline silicon is 0.05 ppba, the amount D of the dopant is added, It can be calculated as 0.2 ppba (carrier concentration A) −0.05 ppba (acceptor concentration C) +0.02 ppba (donor concentration B) = 0.17 ppba. That is, an acceptor dopant in an amount corresponding to 0.17 ppba may be added.
本発明のシリコン単結晶の製造方法では、上記のようにして多結晶シリコンの表面及びバルク部分の不純物濃度に基づいて算出した投入量でドープ剤を投入して、予めシリコン単結晶を製造する。そして、このようにして予め製造したシリコン単結晶の抵抗率を測定し、測定した抵抗率と狙い抵抗率の差異を求める。なお、ここでいう「予め製造したシリコン単結晶の抵抗率」は、そのためだけに別途製造されたシリコン単結晶の抵抗率である必要はなく、前回製造時の実績抵抗率であってもよい。
In the method for producing a silicon single crystal according to the present invention, a silicon single crystal is produced in advance by introducing a dopant in an amount calculated based on the impurity concentration of the surface and bulk portion of polycrystalline silicon as described above. Then, the resistivity of the silicon single crystal thus manufactured in advance is measured, and the difference between the measured resistivity and the target resistivity is obtained. The “resistivity of a silicon single crystal manufactured in advance” here does not have to be the resistivity of a silicon single crystal manufactured separately only for that purpose, and may be an actual resistivity at the time of previous manufacturing.
本発明のシリコン単結晶の製造方法では、このようにして求めた予め製造したシリコン単結晶の抵抗率と狙い抵抗率の差異を、環境汚染量の影響と定義する。なお、本発明では、同じ環境下にある多結晶シリコンの表面は等しく汚染されるものと考える。また、ここでいう「環境」とは、単結晶製造に必要な環境（例えば、多結晶シリコンの保管場所や単結晶を製造する製造室・製造装置）のことであり、より具体的には、多結晶シリコンの表面が接触する、石英ルツボ、リチャージ管や引上室などが含まれる。また、製造されるシリコン単結晶の抵抗率に影響するものとして、環境のＢ（ボロン）及びＰ（リン）が考えられることから、以下では、環境汚染量として、環境のＢ及びＰの量（以下、「環境Ｂ／Ｐ量」と称する）を挙げて説明する。
In the method for producing a silicon single crystal of the present invention, the difference between the resistivity and the target resistivity of the silicon single crystal produced in advance as described above is defined as the influence of the amount of environmental pollution. In the present invention, the surface of polycrystalline silicon under the same environment is considered to be equally contaminated. In addition, the “environment” referred to here is an environment necessary for manufacturing a single crystal (for example, a storage place of polycrystalline silicon or a manufacturing room / manufacturing apparatus for manufacturing a single crystal), and more specifically, It includes a quartz crucible, a recharge tube, a pulling chamber, etc. with which the surface of polycrystalline silicon contacts. In addition, since environmental B (boron) and P (phosphorus) can be considered as affecting the resistivity of the silicon single crystal to be manufactured, in the following, the amount of environmental B and P ( Hereinafter, description will be given by referring to “environment B / P amount”).
環境Ｂ／Ｐ量は、予め製造したシリコン単結晶の抵抗率と狙い抵抗率の差異から逆算して求めることができる。また、環境Ｂ／Ｐ量に係わるイベント時に環境Ｂ／Ｐ量を逆算し、環境レベルを把握することもできる。具体的な環境Ｂ／Ｐ量の逆算方法としては、例えば、クリーンルームのフィルター交換をした場合や、多結晶シリコン、石英ルツボ、リチャージ管等の保管場所を変更した場合に、ある程度の期間における実績抵抗率の推移から実績抵抗率と狙い抵抗率の差異の平均値を求め、これから環境Ｂ／Ｐ量を逆算する方法が挙げられる。このとき、例えば、Ｐ型の抵抗率が低くなった場合は環境Ｂ量、Ｐ型の抵抗率が高くなった場合は環境Ｐ量として逆算することができる。
The amount of environment B / P can be obtained by calculating backward from the difference between the resistivity of the silicon single crystal produced in advance and the target resistivity. In addition, the environment level can be grasped by calculating back the environment B / P amount at the event related to the environment B / P amount. As a specific back-calculation method of the environmental B / P amount, for example, when the filter of a clean room is replaced, or when the storage location of a polycrystalline silicon, a quartz crucible, a recharge tube, etc. is changed, the actual resistance in a certain period An average value of the difference between the actual resistivity and the target resistivity is obtained from the rate transition, and the environmental B / P amount is calculated backward from this. At this time, for example, when the P-type resistivity is low, the environmental B amount can be calculated, and when the P-type resistivity is high, the environmental P amount can be calculated back.
本発明のシリコン単結晶の製造方法では、上述のようにして求めた多結晶シリコンの表面及びバルク部分の不純物濃度と環境Ｂ／Ｐ量に基づいて環境Ｂ／Ｐ量を相殺するようにドープ剤の投入量を調整してシリコン単結晶を製造する。
In the method for producing a silicon single crystal according to the present invention, a dopant is used so as to offset the amount of environmental B / P based on the impurity concentration of the surface and bulk portion of the polycrystalline silicon obtained as described above and the amount of environmental B / P. The silicon single crystal is manufactured by adjusting the amount of the silicon.
このときのドープ剤投入量の調整は、例えば、多結晶シリコンの表面及びバルク部分の不純物濃度、並びに環境Ｂ／Ｐ量を入力してドープ剤の投入量を決定する計算シートを作成し、ドープ剤の投入量を決定する方法で行うことができる。また、製造したシリコン単結晶の抵抗率の測定結果から同計算シートを使用して、環境Ｂ／Ｐ量を逆算し、レベルを把握することもできる。具体的なドープ剤の投入量の計算方法としては、例えば、表計算ソフトに組み込まれているゴールシーク機能を用いて、実績抵抗率と狙い抵抗率の差異の平均値から、環境Ｂ／Ｐ量の逆算及びドープ剤投入量の算出をすることができる。
Adjustment of the dope amount at this time is performed by, for example, creating a calculation sheet for determining the dope amount by inputting the impurity concentration of the surface and bulk portion of the polycrystalline silicon and the amount of environment B / P. This can be done by a method of determining the amount of the agent to be charged. In addition, using the same calculation sheet from the measurement result of the resistivity of the manufactured silicon single crystal, it is possible to reversely calculate the amount of environmental B / P and grasp the level. As a specific calculation method of the amount of the dopant, for example, by using the goal seek function incorporated in the spreadsheet software, the environmental B / P amount is calculated from the average value of the difference between the actual resistivity and the target resistivity. Can be calculated and the amount of dopant added can be calculated.
本発明のシリコン単結晶の製造方法では、このような方法でドープ剤の投入量を調整するため、環境が異なる場合にもその環境に応じた濃度に合わせることにより、同等の抵抗率を有するシリコン単結晶を製造することができる。つまり、環境が変わった場合にも、所望の抵抗率を有するシリコン単結晶を精度よく製造することができる。
In the method for producing a silicon single crystal according to the present invention, since the amount of the dope added is adjusted by such a method, even when the environment is different, by adjusting the concentration according to the environment, silicon having an equivalent resistivity is obtained. Single crystals can be produced. That is, even when the environment changes, a silicon single crystal having a desired resistivity can be manufactured with high accuracy.
なお、環境汚染量を相殺するドープ剤の投入量の調整は、環境汚染量のドナー濃度又はアクセプター濃度の影響量が、狙い抵抗率に対して所定の範囲を超えたときに行うことが好ましい。より具体的には、環境Ｂ／Ｐ量の影響で、予め製造したシリコン単結晶の抵抗率が、狙い抵抗率から概ね±５％以上ずれた場合に、ドープ剤の投入量の調整を行うことが好ましい。このようにして環境汚染量を相殺するドープ剤の投入量の調整を行えば、狙い抵抗率に対する精度を更に向上させることができる。
It should be noted that the adjustment of the amount of the doping agent that offsets the amount of environmental pollution is preferably performed when the influence amount of the donor concentration or acceptor concentration of the environmental contamination amount exceeds a predetermined range with respect to the target resistivity. More specifically, when the resistivity of the silicon single crystal produced in advance is shifted by approximately ± 5% or more from the target resistivity due to the influence of the environmental B / P amount, the amount of dope added should be adjusted. Is preferred. In this way, by adjusting the amount of the dope added to offset the amount of environmental pollution, the accuracy with respect to the target resistivity can be further improved.
以上のように、本発明のシリコン単結晶の製造方法であれば、１０００Ωｃｍ以上の高抵抗率のシリコン単結晶であっても、所望の抵抗率を有するシリコン単結晶を精度よく製造することができる。また、製造するシリコン単結晶の抵抗率を３０００Ωｃｍ以上、あるいは６０００Ωｃｍ以上とした場合にも、抵抗率規格の狭いシリコン単結晶を精度よく製造することができる。また、環境汚染量の異なる製造環境であっても、１０００Ωｃｍ以上の高抵抗率のシリコン単結晶を精度よく製造することができる。なお、本発明で製造するシリコン単結晶の抵抗率は１０００Ωｃｍ以上であり、上限は特に限定されないが、例えば３００００Ωｃｍ以下とすることで、抵抗率規格の狭いシリコン単結晶をより精度よく製造することができる。
As described above, the silicon single crystal manufacturing method of the present invention can accurately manufacture a silicon single crystal having a desired resistivity even if it is a silicon single crystal having a high resistivity of 1000 Ωcm or more. . Further, even when the resistivity of the silicon single crystal to be manufactured is 3000 Ωcm or more, or 6000 Ωcm or more, a silicon single crystal having a narrow resistivity standard can be manufactured with high accuracy. In addition, even in a manufacturing environment with different amounts of environmental pollution, a silicon single crystal having a high resistivity of 1000 Ωcm or more can be accurately manufactured. In addition, the resistivity of the silicon single crystal produced by the present invention is 1000 Ωcm or more, and the upper limit is not particularly limited. For example, by setting the resistivity to 30000 Ωcm or less, it is possible to produce a silicon single crystal having a narrow resistivity standard more accurately. it can.
以下、実施例及び比較例を用いて本発明を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。
Hereinafter, the present invention will be specifically described using examples and comparative examples, but the present invention is not limited thereto.
まず、環境汚染量（環境Ｂ／Ｐ量）を考慮してドープ剤の投入量を調整することで、狙い抵抗率に対する精度が向上するか確認を行った。
First, it was confirmed whether the accuracy with respect to the target resistivity was improved by adjusting the amount of the dope added in consideration of the amount of environmental pollution (environmental B / P amount).
［比較例１］
原料となる多結晶シリコンを用意し、上述のＩＣＰ－ＭＳを用いた定量分析によって、多結晶シリコンの表面及びバルク部分のドナー濃度とアクセプター濃度を測定したところ、多結晶シリコンの表面及びバルク部分の合計のドナー濃度は０．０３ｐｐｂａ、多結晶シリコンの表面及びバルク部分の合計のアクセプター濃度は０．０３ｐｐｂａであった。次に、この測定結果に基づいて、狙い抵抗率Ｐ型２５００Ωｃｍで、上述のドープ剤の投入量の決定方法によりドープ剤の投入量を求めた。多結晶シリコンに、求めた投入量でドープ剤を投入して、実際に口径６００ｍｍ（２４インチ）の石英ルツボを用いて直径２００ｍｍのシリコン単結晶を製造し、製造したシリコン単結晶の抵抗率（実績抵抗率）を測定した。測定した抵抗率は、Ｐ型約２８００Ωｃｍであり、狙い抵抗率に対するズレ量は＋１２％程度であった。 [Comparative Example 1]
Polycrystalline silicon as a raw material was prepared, and the donor concentration and acceptor concentration of the surface and bulk portion of the polycrystalline silicon were measured by the quantitative analysis using the above-described ICP-MS. The total donor concentration was 0.03 ppba, and the total acceptor concentration of the polycrystalline silicon surface and bulk portion was 0.03 ppba. Next, based on the measurement results, the amount of the dope added was determined by the above-described method for determining the amount of the dope added with the target resistivity P type 2500 Ωcm. The polycrystalline silicon is charged with the doping amount obtained, and a silicon single crystal having a diameter of 200 mm is actually manufactured using a quartz crucible having a diameter of 600 mm (24 inches), and the resistivity of the manufactured silicon single crystal ( Actual resistivity) was measured. The measured resistivity was P-type of about 2800 Ωcm, and the deviation from the target resistivity was about + 12%.
原料となる多結晶シリコンを用意し、上述のＩＣＰ－ＭＳを用いた定量分析によって、多結晶シリコンの表面及びバルク部分のドナー濃度とアクセプター濃度を測定したところ、多結晶シリコンの表面及びバルク部分の合計のドナー濃度は０．０３ｐｐｂａ、多結晶シリコンの表面及びバルク部分の合計のアクセプター濃度は０．０３ｐｐｂａであった。次に、この測定結果に基づいて、狙い抵抗率Ｐ型２５００Ωｃｍで、上述のドープ剤の投入量の決定方法によりドープ剤の投入量を求めた。多結晶シリコンに、求めた投入量でドープ剤を投入して、実際に口径６００ｍｍ（２４インチ）の石英ルツボを用いて直径２００ｍｍのシリコン単結晶を製造し、製造したシリコン単結晶の抵抗率（実績抵抗率）を測定した。測定した抵抗率は、Ｐ型約２８００Ωｃｍであり、狙い抵抗率に対するズレ量は＋１２％程度であった。 [Comparative Example 1]
Polycrystalline silicon as a raw material was prepared, and the donor concentration and acceptor concentration of the surface and bulk portion of the polycrystalline silicon were measured by the quantitative analysis using the above-described ICP-MS. The total donor concentration was 0.03 ppba, and the total acceptor concentration of the polycrystalline silicon surface and bulk portion was 0.03 ppba. Next, based on the measurement results, the amount of the dope added was determined by the above-described method for determining the amount of the dope added with the target resistivity P type 2500 Ωcm. The polycrystalline silicon is charged with the doping amount obtained, and a silicon single crystal having a diameter of 200 mm is actually manufactured using a quartz crucible having a diameter of 600 mm (24 inches), and the resistivity of the manufactured silicon single crystal ( Actual resistivity) was measured. The measured resistivity was P-type of about 2800 Ωcm, and the deviation from the target resistivity was about + 12%.
同様にして、環境Ｂ／Ｐ量を考慮せずに、狙い抵抗率Ｐ型５００００Ωｃｍ以下でシリコン単結晶を複数製造し、製造したシリコン単結晶の抵抗率を測定した。製造したシリコン単結晶の計算抵抗率（狙い抵抗率）［ｘ軸］と実績抵抗率［ｙ軸］との関係を図２に示す。また、狙い抵抗率Ｐ型１０００～３０００Ωｃｍでシリコン単結晶を製造した場合の、狙い抵抗率に対するズレ量とそのばらつきを図４に、狙い抵抗率Ｐ型６０００Ωｃｍでシリコン単結晶を製造した場合の、狙い抵抗率に対するズレ量とそのばらつきを図５に、それぞれ示す。
Similarly, without considering the environmental B / P amount, a plurality of silicon single crystals were manufactured with a target resistivity P-type of 50000 Ωcm or less, and the resistivity of the manufactured silicon single crystals was measured. The relationship between the calculated resistivity (target resistivity) [x axis] and the actual resistivity [y axis] of the manufactured silicon single crystal is shown in FIG. In addition, when the silicon single crystal is manufactured with a target resistivity of P-type 1000 to 3000 Ωcm, the amount of deviation with respect to the target resistivity and its variation are shown in FIG. 4, and when the silicon single crystal is manufactured with the target resistivity of P-type 6000 Ωcm, FIG. 5 shows the amount of deviation with respect to the target resistivity and its variation.
［実施例１］
図２に基づいて、比較例１で製造したシリコン単結晶の実績抵抗率と狙い抵抗率（計算抵抗率）との差異を求め、この差異を環境汚染量（環境１の環境Ｂ／Ｐ量）の影響と定義し、この差異から環境Ｂ量を０．０１ｐｐｂａと逆算した。次に、上記のようにして測定した多結晶シリコンの表面及びバルク部分のドナー濃度とアクセプター濃度に加えて、上記のようにして求めた環境Ｂ量を考慮して、狙い抵抗率Ｐ型２５００Ωｃｍで、環境汚染量を相殺するようなドープ剤の投入量を求めた。次に、多結晶シリコンに求めた投入量でドープ剤を投入して、口径６００ｍｍ（２４インチ）の石英ルツボを用いて直径２００ｍｍのシリコン単結晶を製造し、製造したシリコン単結晶の抵抗率（実績抵抗率）を測定した。測定した抵抗率は、Ｐ型約２６００Ωｃｍであり、狙い抵抗率に対するズレ量は＋４％であった。 [Example 1]
Based on FIG. 2, the difference between the actual resistivity and the target resistivity (calculated resistivity) of the silicon single crystal manufactured in Comparative Example 1 is obtained, and this difference is calculated as the amount of environmental pollution (environmental B / P amount in environment 1). From this difference, the amount of environment B was calculated back to 0.01 ppba. Next, in addition to the donor concentration and acceptor concentration of the surface and bulk portion of the polycrystalline silicon measured as described above, the target resistivity P-type 2500 Ωcm in consideration of the environment B amount obtained as described above. Then, the amount of the dope added so as to offset the amount of environmental pollution was determined. Next, a doping agent is added in the amount required for polycrystalline silicon, a silicon single crystal having a diameter of 200 mm is manufactured using a quartz crucible having a diameter of 600 mm (24 inches), and the resistivity of the manufactured silicon single crystal ( Actual resistivity) was measured. The measured resistivity was about 2600 Ωcm P-type, and the deviation from the target resistivity was + 4%.
図２に基づいて、比較例１で製造したシリコン単結晶の実績抵抗率と狙い抵抗率（計算抵抗率）との差異を求め、この差異を環境汚染量（環境１の環境Ｂ／Ｐ量）の影響と定義し、この差異から環境Ｂ量を０．０１ｐｐｂａと逆算した。次に、上記のようにして測定した多結晶シリコンの表面及びバルク部分のドナー濃度とアクセプター濃度に加えて、上記のようにして求めた環境Ｂ量を考慮して、狙い抵抗率Ｐ型２５００Ωｃｍで、環境汚染量を相殺するようなドープ剤の投入量を求めた。次に、多結晶シリコンに求めた投入量でドープ剤を投入して、口径６００ｍｍ（２４インチ）の石英ルツボを用いて直径２００ｍｍのシリコン単結晶を製造し、製造したシリコン単結晶の抵抗率（実績抵抗率）を測定した。測定した抵抗率は、Ｐ型約２６００Ωｃｍであり、狙い抵抗率に対するズレ量は＋４％であった。 [Example 1]
Based on FIG. 2, the difference between the actual resistivity and the target resistivity (calculated resistivity) of the silicon single crystal manufactured in Comparative Example 1 is obtained, and this difference is calculated as the amount of environmental pollution (environmental B / P amount in environment 1). From this difference, the amount of environment B was calculated back to 0.01 ppba. Next, in addition to the donor concentration and acceptor concentration of the surface and bulk portion of the polycrystalline silicon measured as described above, the target resistivity P-type 2500 Ωcm in consideration of the environment B amount obtained as described above. Then, the amount of the dope added so as to offset the amount of environmental pollution was determined. Next, a doping agent is added in the amount required for polycrystalline silicon, a silicon single crystal having a diameter of 200 mm is manufactured using a quartz crucible having a diameter of 600 mm (24 inches), and the resistivity of the manufactured silicon single crystal ( Actual resistivity) was measured. The measured resistivity was about 2600 Ωcm P-type, and the deviation from the target resistivity was + 4%.
同様にして、環境Ｂ／Ｐ量を考慮して、狙い抵抗率Ｐ型５００００Ωｃｍ以下でシリコン単結晶を複数製造し、製造したシリコン単結晶の抵抗率を測定した。製造したシリコン単結晶の計算抵抗率（狙い抵抗率）［ｘ軸］と実績抵抗率［ｙ軸］との関係を図３に示す。また、狙い抵抗率Ｐ型１０００～３０００Ωｃｍでシリコン単結晶を製造した場合の、狙い抵抗率に対するズレ量とそのばらつきを図４に、狙い抵抗率Ｐ型６０００Ωｃｍでシリコン単結晶を製造した場合の、狙い抵抗率に対するズレ量とそのばらつきを図５に、それぞれ示す。
Similarly, in consideration of the amount of environment B / P, a plurality of silicon single crystals were manufactured with a target resistivity P-type of 50000 Ωcm or less, and the resistivity of the manufactured silicon single crystals was measured. FIG. 3 shows the relationship between the calculated resistivity (target resistivity) [x-axis] and the actual resistivity [y-axis] of the manufactured silicon single crystal. In addition, when the silicon single crystal is manufactured with a target resistivity of P-type 1000 to 3000 Ωcm, the amount of deviation with respect to the target resistivity and its variation are shown in FIG. 4, and when the silicon single crystal is manufactured with the target resistivity of P-type 6000 Ωcm, FIG. 5 shows the amount of deviation with respect to the target resistivity and its variation.
図２、３に示されるように、環境Ｂ／Ｐ量を考慮した本発明の製造方法でシリコン単結晶を製造した実施例１では、環境Ｂ／Ｐ量を含めて多結晶シリコンの表面及びバルク部分の不純物濃度からドープ剤の投入量を計算した結果、あらゆる狙い抵抗率においてシリコン単結晶の計算抵抗率と近い結果となることが確認された。一方、環境Ｂ／Ｐ量を考慮しない従来の製造方法でシリコン単結晶を製造した比較例１では、計算抵抗率が実際の抵抗率よりも高くなる場合が多かった。
As shown in FIGS. 2 and 3, in Example 1 in which the silicon single crystal was manufactured by the manufacturing method of the present invention in consideration of the environmental B / P amount, the surface and bulk of the polycrystalline silicon including the environmental B / P amount were obtained. As a result of calculating the dose of the dopant from the impurity concentration of the portion, it was confirmed that the results were close to the calculated resistivity of the silicon single crystal at any target resistivity. On the other hand, in Comparative Example 1 in which a silicon single crystal was manufactured by a conventional manufacturing method that does not consider the environmental B / P amount, the calculated resistivity was often higher than the actual resistivity.
また、図４、５に示されるように、環境Ｂ／Ｐ量を考慮した本発明の製造方法でシリコン単結晶を製造した実施例１では、狙い抵抗率Ｐ型１０００～３０００Ωｃｍ、６０００Ωｃｍのいずれの場合でも、環境Ｂ／Ｐ量を考慮しない従来の製造方法でシリコン単結晶を製造した比較例１に比べて、狙い抵抗率に対する実際の抵抗率のズレ量が小さく、所望の抵抗率を有するシリコン単結晶を精度よく製造できていた。特に、高抵抗率においての狙い抵抗率に対する精度の向上が顕著であった。
In addition, as shown in FIGS. 4 and 5, in Example 1 in which a silicon single crystal was manufactured by the manufacturing method of the present invention in consideration of the amount of environmental B / P, any one of the target resistivity P-type 1000 to 3000 Ωcm and 6000 Ωcm was obtained. Even in this case, compared to Comparative Example 1 in which a silicon single crystal is manufactured by a conventional manufacturing method that does not consider the amount of environmental B / P, the actual resistivity shift amount with respect to the target resistivity is small, and silicon having a desired resistivity is obtained. Single crystals could be manufactured with high accuracy. In particular, the improvement in accuracy with respect to the target resistivity at a high resistivity was remarkable.
次に、環境が異なる場所（環境２）で保管した多結晶シリコンを用いて、同様に狙い抵抗率に対する精度が向上するか確認を行った。
Next, using polycrystalline silicon stored in a different environment (Environment 2), it was confirmed whether the accuracy with respect to the target resistivity was improved.
［比較例２］
環境由来のアクセプター濃度が環境１＞環境２である（つまり、アクセプタードープ濃度は環境１＞環境２となる）２種類の環境（環境１、２）で保管した多結晶シリコンを用いて、比較例１と同様に環境Ｂ／Ｐ量を考慮せずに狙い抵抗率Ｐ型１０００～３０００Ωｃｍ、６０００Ωｃｍ、１００００Ωｃｍ超でシリコン単結晶を製造し、製造したシリコン単結晶の抵抗率を測定した。また、ドナー濃度の比率を１とした場合の、環境由来のアクセプター濃度と多結晶シリコンのバルク・表面及びドープ剤由来のアクセプター濃度の比率を求めた。結果をそれぞれ図６、７、８に示す。 [Comparative Example 2]
Using polycrystalline silicon stored in two environments (environment 1 and environment 2) where the environment-derived acceptor concentration is environment 1> environment 2 (that is, acceptor dope concentration is environment 1> environment 2) Similarly to Example 1, a silicon single crystal was manufactured with a resistivity P-type of 1000 to 3000 Ωcm, 6000 Ωcm, and more than 10000 Ωcm without considering the amount of environment B / P, and the resistivity of the manufactured silicon single crystal was measured. Further, the ratio of the acceptor concentration derived from the environment to the bulk / surface of polycrystalline silicon and the acceptor derived from the dopant when the donor concentration ratio was set to 1 was determined. The results are shown in FIGS.
環境由来のアクセプター濃度が環境１＞環境２である（つまり、アクセプタードープ濃度は環境１＞環境２となる）２種類の環境（環境１、２）で保管した多結晶シリコンを用いて、比較例１と同様に環境Ｂ／Ｐ量を考慮せずに狙い抵抗率Ｐ型１０００～３０００Ωｃｍ、６０００Ωｃｍ、１００００Ωｃｍ超でシリコン単結晶を製造し、製造したシリコン単結晶の抵抗率を測定した。また、ドナー濃度の比率を１とした場合の、環境由来のアクセプター濃度と多結晶シリコンのバルク・表面及びドープ剤由来のアクセプター濃度の比率を求めた。結果をそれぞれ図６、７、８に示す。 [Comparative Example 2]
Using polycrystalline silicon stored in two environments (
［実施例２］
上記と同様の２種類の環境（環境１、２）で保管した多結晶シリコンを用いて、実施例１と同様に環境Ｂ／Ｐ量を考慮して狙い抵抗率Ｐ型１０００～３０００Ωｃｍ、６０００Ωｃｍ、１００００Ωｃｍ超でシリコン単結晶を製造し、製造したシリコン単結晶の抵抗率を測定した。また、ドナー濃度の比率を１とした場合の、環境由来のアクセプター濃度と多結晶シリコンのバルク・表面及びドープ剤由来のアクセプター濃度の比率を求めた。結果をそれぞれ図６、７、８に示す。 [Example 2]
Using polycrystalline silicon stored in the same two kinds of environments (environments 1 and 2) as described above, the resistivity P-type 1000 to 3000 Ωcm, 6000 Ωcm, A silicon single crystal was produced at a thickness exceeding 10,000 Ωcm, and the resistivity of the produced silicon single crystal was measured. Further, the ratio of the acceptor concentration derived from the environment to the bulk / surface of polycrystalline silicon and the acceptor derived from the dopant when the donor concentration ratio was set to 1 was determined. The results are shown in FIGS.
上記と同様の２種類の環境（環境１、２）で保管した多結晶シリコンを用いて、実施例１と同様に環境Ｂ／Ｐ量を考慮して狙い抵抗率Ｐ型１０００～３０００Ωｃｍ、６０００Ωｃｍ、１００００Ωｃｍ超でシリコン単結晶を製造し、製造したシリコン単結晶の抵抗率を測定した。また、ドナー濃度の比率を１とした場合の、環境由来のアクセプター濃度と多結晶シリコンのバルク・表面及びドープ剤由来のアクセプター濃度の比率を求めた。結果をそれぞれ図６、７、８に示す。 [Example 2]
Using polycrystalline silicon stored in the same two kinds of environments (
図６～８に示されるように、環境Ｂ／Ｐ量を考慮した本発明の製造方法でシリコン単結晶を製造した実施例２では、いずれの狙い抵抗率においても、環境１、２で実際の抵抗率にほとんど差が生じておらず、また狙い抵抗率に対する精度も良好であった。一方、環境Ｂ／Ｐ量を考慮しない従来の製造方法でシリコン単結晶を製造した比較例２では、いずれの狙い抵抗率においても、環境１、２で実際の抵抗率に差が生じており、特に狙い抵抗率が高い場合に大きな差が生じていた。なお、比較例２では、アクセプター濃度がより高い環境１で保管した多結晶シリコンを用いてシリコン単結晶を製造した場合には、環境２で保管した多結晶シリコンを用いた場合より、実際の抵抗率が低くなる傾向があった。また、比較例２では、狙い抵抗率に対する精度も実施例２に比べて劣っていた。このことから、本発明の製造方法であれば、環境Ｂ／Ｐ量が変化しても環境Ｂ／Ｐ量を把握し、それを考慮したドープ量計算により、狙い抵抗率に対する精度を向上させることが可能であることが示された。
As shown in FIGS. 6 to 8, in Example 2 in which a silicon single crystal was manufactured by the manufacturing method of the present invention in consideration of the amount of environmental B / P, the actual resistivity was measured in environments 1 and 2 at any target resistivity. There was almost no difference in resistivity, and the accuracy with respect to the target resistivity was good. On the other hand, in Comparative Example 2 in which the silicon single crystal was manufactured by the conventional manufacturing method that does not consider the amount of environment B / P, there is a difference in the actual resistivity in environments 1 and 2 at any target resistivity. There was a big difference especially when the target resistivity was high. In Comparative Example 2, when a silicon single crystal is manufactured using polycrystalline silicon stored in environment 1 having a higher acceptor concentration, the actual resistance is higher than in the case of using polycrystalline silicon stored in environment 2. The rate tended to be low. Moreover, in the comparative example 2, the precision with respect to the target resistivity was also inferior compared with the example 2. From this, if it is a manufacturing method of this invention, even if environmental B / P amount changes, environmental B / P amount will be grasped, and dope amount calculation in consideration of it will improve the accuracy to the target resistivity. Was shown to be possible.
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。
Note that the present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.
Claims (3)
- ＣＺ法により１０００Ωｃｍ以上の高抵抗率のシリコン単結晶を製造する方法であって、
予め原料となる多結晶シリコンの表面及びバルク部分の不純物濃度に基づいてドープ剤の投入量を調整して製造したシリコン単結晶の抵抗率と狙い抵抗率の差異を求め、この差異を環境汚染量の影響と定義し、次に前記多結晶シリコンの表面及びバルク部分の不純物濃度と前記環境汚染量に基づいて前記環境汚染量を相殺するように前記ドープ剤の投入量を調整してシリコン単結晶を製造することを特徴とするシリコン単結晶の製造方法。 A method for producing a silicon single crystal having a high resistivity of 1000 Ωcm or more by a CZ method,
The difference between the resistivity and the target resistivity of the silicon single crystal produced by adjusting the dose of the dopant based on the impurity concentration in the surface and bulk part of the polycrystalline silicon used as a raw material in advance is calculated. Next, the doping amount of the dopant is adjusted so as to offset the amount of environmental contamination based on the impurity concentration of the surface and bulk portion of the polycrystalline silicon and the amount of environmental contamination. A method for producing a silicon single crystal, characterized by comprising: - 前記環境汚染量を相殺するドープ剤の投入量の調整は、前記環境汚染量のドナー濃度又はアクセプター濃度の影響量が、前記狙い抵抗率に対して所定の範囲を超えたときに行うことを特徴とする請求項１に記載のシリコン単結晶の製造方法。 The adjustment of the input amount of the dopant that offsets the environmental pollution amount is performed when the influence amount of the donor concentration or acceptor concentration of the environmental pollution amount exceeds a predetermined range with respect to the target resistivity. The method for producing a silicon single crystal according to claim 1.
- 前記シリコン単結晶として、抵抗率６０００Ωｃｍ以上のシリコン単結晶を製造することを特徴とする請求項１又は請求項２に記載のシリコン単結晶の製造方法。 The method for producing a silicon single crystal according to claim 1 or 2, wherein a silicon single crystal having a resistivity of 6000 Ωcm or more is produced as the silicon single crystal.
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