JP6459900B2 - Inspection method of silicon wafer - Google Patents
Inspection method of silicon wafer Download PDFInfo
- Publication number
- JP6459900B2 JP6459900B2 JP2015209676A JP2015209676A JP6459900B2 JP 6459900 B2 JP6459900 B2 JP 6459900B2 JP 2015209676 A JP2015209676 A JP 2015209676A JP 2015209676 A JP2015209676 A JP 2015209676A JP 6459900 B2 JP6459900 B2 JP 6459900B2
- Authority
- JP
- Japan
- Prior art keywords
- sample
- temperature
- inspection
- oxygen
- silicon wafer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000000034 method Methods 0.000 title claims description 98
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims description 77
- 229910052710 silicon Inorganic materials 0.000 title claims description 76
- 239000010703 silicon Substances 0.000 title claims description 76
- 238000007689 inspection Methods 0.000 title claims description 56
- 239000000523 sample Substances 0.000 claims description 204
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 105
- 229910052760 oxygen Inorganic materials 0.000 claims description 105
- 239000001301 oxygen Substances 0.000 claims description 105
- 239000002244 precipitate Substances 0.000 claims description 84
- 239000013078 crystal Substances 0.000 claims description 70
- 230000006798 recombination Effects 0.000 claims description 53
- 238000005215 recombination Methods 0.000 claims description 53
- 239000013074 reference sample Substances 0.000 claims description 51
- 238000012360 testing method Methods 0.000 claims description 45
- 238000010438 heat treatment Methods 0.000 claims description 37
- 230000007547 defect Effects 0.000 claims description 29
- 238000011088 calibration curve Methods 0.000 claims description 27
- 238000003486 chemical etching Methods 0.000 claims description 26
- 238000001816 cooling Methods 0.000 claims description 19
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 18
- 238000005259 measurement Methods 0.000 claims description 17
- 238000005530 etching Methods 0.000 claims description 16
- 238000003325 tomography Methods 0.000 claims description 16
- 239000007864 aqueous solution Substances 0.000 claims description 9
- 229910021332 silicide Inorganic materials 0.000 claims description 8
- FVBUAEGBCNSCDD-UHFFFAOYSA-N silicide(4-) Chemical compound [Si-4] FVBUAEGBCNSCDD-UHFFFAOYSA-N 0.000 claims description 8
- 238000004140 cleaning Methods 0.000 claims description 6
- 238000000151 deposition Methods 0.000 claims 1
- 239000010949 copper Substances 0.000 description 128
- 235000012431 wafers Nutrition 0.000 description 41
- 229910052802 copper Inorganic materials 0.000 description 14
- 239000000243 solution Substances 0.000 description 14
- 238000009792 diffusion process Methods 0.000 description 12
- 238000009826 distribution Methods 0.000 description 11
- 229910052723 transition metal Inorganic materials 0.000 description 11
- 150000003624 transition metals Chemical class 0.000 description 11
- 238000011109 contamination Methods 0.000 description 10
- 230000007704 transition Effects 0.000 description 9
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 238000005034 decoration Methods 0.000 description 7
- 238000012423 maintenance Methods 0.000 description 7
- 229910052759 nickel Inorganic materials 0.000 description 7
- XTVVROIMIGLXTD-UHFFFAOYSA-N copper(II) nitrate Chemical compound [Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O XTVVROIMIGLXTD-UHFFFAOYSA-N 0.000 description 6
- 238000001556 precipitation Methods 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- 238000012790 confirmation Methods 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- QPJSUIGXIBEQAC-UHFFFAOYSA-N n-(2,4-dichloro-5-propan-2-yloxyphenyl)acetamide Chemical compound CC(C)OC1=CC(NC(C)=O)=C(Cl)C=C1Cl QPJSUIGXIBEQAC-UHFFFAOYSA-N 0.000 description 4
- 230000003746 surface roughness Effects 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- -1 Heat treatment Substances 0.000 description 3
- 239000011651 chromium Substances 0.000 description 3
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 230000001376 precipitating effect Effects 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- ZFYIQPIHXRFFCZ-QMMMGPOBSA-N (2s)-2-(cyclohexylamino)butanedioic acid Chemical compound OC(=O)C[C@@H](C(O)=O)NC1CCCCC1 ZFYIQPIHXRFFCZ-QMMMGPOBSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 235000018734 Sambucus australis Nutrition 0.000 description 1
- 244000180577 Sambucus australis Species 0.000 description 1
- 230000006399 behavior Effects 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 238000003776 cleavage reaction Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 125000000896 monocarboxylic acid group Chemical group 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000007017 scission Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Landscapes
- Crystals, And After-Treatments Of Crystals (AREA)
- Testing Or Measuring Of Semiconductors Or The Like (AREA)
Description
本発明は、選択エッチングを行うことなく、ウェーハの酸素析出欠陥領域を高精度で簡易に識別し、環境や人体に安全な方法でシリコンウェーハを検査する方法に関する。 The present invention relates to a method for inspecting a silicon wafer in a safe manner for the environment and a human body by easily and accurately identifying an oxygen precipitation defect region of a wafer without performing selective etching.
シリコンウェーハを製造するためのシリコン単結晶の育成方法としてチョクラルスキー法（以下、ＣＺ法という。）が広く用いられている。このＣＺ法では、シリコン単結晶育成時に結晶内部に導入される酸素起因の欠陥の種類及び分布は、結晶の引上げ速度Ｖと固液界面の温度勾配Ｇに依存することが知られている。このＶ／Ｇの比がある値以上になると、空孔が過剰になり、原子空孔が集まったボイド欠陥であるＣＯＰ(Crystal Originated Particle)が発生する。一方、Ｖ／Ｇの比が小さい場合には、格子間シリコン原子が過剰となり、格子間シリコンの凝集体である転移クラスタが発生する。更に、上記ＣＯＰが発生する領域と転移クラスタが発生する領域の間には、熱処理された場合の挙動が異なる複数の領域が存在する。 The Czochralski method (hereinafter referred to as CZ method) is widely used as a method for growing a silicon single crystal for manufacturing a silicon wafer. In this CZ method, it is known that the type and distribution of oxygen-induced defects introduced into the crystal during the growth of the silicon single crystal depend on the crystal pulling rate V and the temperature gradient G at the solid-liquid interface. When the ratio of V / G exceeds a certain value, vacancies become excessive and COP (Crystal Originated Particles), which are void defects in which atomic vacancies are collected, are generated. On the other hand, when the V / G ratio is small, the number of interstitial silicon atoms becomes excessive, and transition clusters that are aggregates of interstitial silicon are generated. Further, there are a plurality of regions having different behaviors when heat-treated between the region where the COP is generated and the region where the transition cluster is generated.
ＣＯＰが発生する領域と転移クラスタが発生する領域の間には、Ｖ／Ｇの比が大きい方から順に、ＯＳＦ領域、Ｐv領域、Ｐi領域の３つの領域が存在する。ＯＳＦ領域とは、結晶育成後に何の熱履歴も受けていないas-grown状態で酸素積層欠陥(Oxidation induced Stacking Fault、ＯＳＦ)核を含み、１０００℃以上の高温で熱酸化した場合にＯＳＦが顕在化する領域である。Ｐv領域とは、as-grown状態で酸素析出核が存在し、熱処理を施した場合に酸素析出物が発生する領域である。Ｐi領域とは、as-grown状態で殆ど酸素析出核が存在せず、熱処理を施されても酸素析出物が発生し難い領域である。上記ＣＯＰ及び転移クラスタは半導体デバイスの特性に大きな影響を与えるため、これらの欠陥が発生しない条件でシリコン単結晶を育成することが望ましい。そのためには、育成したシリコン単結晶の検査を行い、各領域の分布を正確に把握し、結晶育成に対して必要なフィードバックをかけることが重要である。 Between the region where the COP is generated and the region where the transfer cluster is generated, there are three regions, the OSF region, the Pv region, and the Pi region, in descending order of the V / G ratio. The OSF region includes oxygen-induced stacking fault (OSF) nuclei in an as-grown state that has not undergone any thermal history after crystal growth, and the OSF is manifested when thermally oxidized at a high temperature of 1000 ° C. or higher. It is an area to be converted. The Pv region is a region where oxygen precipitate nuclei exist in an as-grown state and oxygen precipitates are generated when heat treatment is performed. The Pi region is a region in which almost no oxygen precipitation nuclei are present in the as-grown state, and oxygen precipitates are hardly generated even when heat treatment is performed. Since the COP and the transition cluster have a great influence on the characteristics of the semiconductor device, it is desirable to grow a silicon single crystal under the condition that these defects do not occur. For this purpose, it is important to inspect the grown silicon single crystal, accurately grasp the distribution of each region, and give necessary feedback to the crystal growth.
従来、シリコン単結晶中の各領域を判別する方法としては、Ｃｕデコレーション法（例えば、特許文献１参照。）及び赤外散乱トモグラフィ法（例えば、特許文献２参照。）が広く知られている。Ｃｕデコレーション法は、サンプル表面に付着させたＣｕを熱処理によりサンプル内部に拡散させた後に急冷によって結晶表面の欠陥を顕在化させる方法である。特許文献１には、Ｃｕ又はＮｉのデコレーション法を行った後に、ライト(Wright)液による選択エッチングや、セコ(Secco)液による選択エッチングを行って、サンプル表面のＣｕ析出物又はＮｉ析出物をピットとして検出することが記載されている。上記ライト液は、ＨＦ、ＨＮＯ３、Ｃｒ２Ｏ３、Ｃｕ(ＮＯ３) ２、ＣＨ３ＣＯＯＨ及びＨ２Ｏを含有する。一方上記セコ液は、ＨＦ、Ｋ２Ｃｒ２Ｏ７及びＨ２Ｏを含有する。 Conventionally, as a method for discriminating each region in a silicon single crystal, a Cu decoration method (for example, see Patent Document 1) and an infrared scattering tomography method (for example, see Patent Document 2) are widely known. . The Cu decoration method is a method in which a defect on the crystal surface is revealed by rapid cooling after Cu adhering to the sample surface is diffused into the sample by heat treatment. In Patent Document 1, after performing a decoration method of Cu or Ni, selective etching with a Wright liquid or selective etching with a Secco liquid is performed to obtain Cu precipitates or Ni precipitates on the sample surface. It is described that it is detected as a pit. The light liquid contains HF, HNO 3 , Cr 2 O 3 , Cu (NO 3 ) 2 , CH 3 COOH, and H 2 O. On the other hand, the Seco solution contains HF, K 2 Cr 2 O 7 and H 2 O.
また、特許文献２には、赤外散乱トモグラフィ法は、シリコン基板をへき開し、その断面方向からＳｉ結晶を透過する赤外線を照射し、Ｓｉ結晶中の微小欠陥からの散乱光線をカメラで撮影する方法である旨が記載されている。 Patent Document 2 discloses an infrared scattering tomography method in which a silicon substrate is cleaved and irradiated with infrared rays that pass through a Si crystal from a cross-sectional direction, and a scattered light from a minute defect in the Si crystal is photographed with a camera. It is described that it is a method to do.
特許文献１に記載された方法は、Ｃｕ又はＮｉを熱処理によりサンプル内部に拡散させた後に、サンプルを急冷するため、過飽和なＣｕ又はＮｉもサンプル内に取り残され、シリコン単結晶の各領域を評価するときに、外乱となる恐れがある。また選択エッチング液であるライト液又はセコ液には、いずれも環境や人体に有害なクロムを含み、エッチング液の処理が煩わしい問題があった。特許文献２に記載された方法は、特許文献１に記載された方法の課題がない代わりに、赤外散乱トモグラフィ装置は高価でかつ測定に長時間を要する問題があった。 In the method described in Patent Document 1, Cu or Ni is diffused into the sample by heat treatment, and then the sample is rapidly cooled. Therefore, supersaturated Cu or Ni is also left in the sample, and each region of the silicon single crystal is evaluated. There is a risk of disturbance. In addition, both the light solution and the secco solution, which are selective etching solutions, contain chromium harmful to the environment and the human body, and there is a problem that the processing of the etching solution is troublesome. The method described in Patent Document 2 has a problem that the infrared scattering tomography apparatus is expensive and takes a long time for measurement, instead of having the problem of the method described in Patent Document 1.
本発明の第１の目的は、外乱をなくしてシリコンウェーハ内のＣｕの再結合ライフタイムを検査する方法を提供することにある。本発明の第２の目的は、選択エッチングを行うことなく、シリコンウェーハの酸素析出欠陥領域を高精度で簡易に識別し、環境や人体に安全な方法でシリコンウェーハを検査する方法を提供することにある。 A first object of the present invention is to provide a method for inspecting the recombination lifetime of Cu in a silicon wafer without disturbance. A second object of the present invention is to provide a method for inspecting a silicon wafer in a safe manner for the environment and the human body by easily and accurately identifying the oxygen precipitation defect region of the silicon wafer without performing selective etching. It is in.
本発明者は、上記目的を達成するために、以下の知見を得て、本発明に到達した。
(1) 特許文献１に示されるＣｕ又はＮｉのデコレーション法での急峻な冷却では、Ｃｕ又はＮｉの遷移金属が酸素析出物に的確にデコレーションせず、遷移金属単体で結晶中に析出し、それらが遷移金属の再結合ライフタイムに影響を及ぼし、シリコン単結晶のようなサンプルの酸素析出物分布を正確に反映しない。
(2) 遷移金属のサンプルに対する固溶度を基準にし、サンプル内に遷移金属を拡散した後の冷却速度を調整すれば、シリコン単結晶内に取り残される遷移金属の量が低減され、かつ遷移金属はサンプル内ではなくサンプル表面に析出する。それらを更に除去すれば、サンプル内は酸素析出物に遷移金属がデコレーションした領域のみになり、サンプルを検査するときの外乱がなくなり、遷移金属の再結合ライフタイムは酸素析出物を正確に反映する。
(3) 具体的には、サンプルの酸素析出物分布と遷移金属の再結合ライフタイム分布の検量線を予め作成しておき、上記(2)の方法で遷移金属の再結合ライフタイムを測定し、これを上記検量線に照合すれば、特許文献１のような選択エッチングを行って酸素析出物を顕在化させる必要はなく、サンプルの酸素析出物を正確に推定することができる。
In order to achieve the above object, the present inventor obtained the following knowledge and reached the present invention.
(1) In the rapid cooling by the decoration method of Cu or Ni shown in Patent Document 1, the transition metal of Cu or Ni does not accurately decorate the oxygen precipitate, and the transition metal alone precipitates in the crystal. Affects the transition metal recombination lifetime and does not accurately reflect the oxygen precipitate distribution of a sample such as a silicon single crystal.
(2) By adjusting the cooling rate after diffusing the transition metal into the sample based on the solid solubility of the transition metal in the sample, the amount of transition metal left in the silicon single crystal can be reduced, and the transition metal Precipitates on the surface of the sample, not within the sample. If they are further removed, the sample will only contain transition metal decorated regions with oxygen precipitates, eliminating disturbances when inspecting the sample, and transition metal recombination lifetimes accurately reflect oxygen precipitates. .
(3) Specifically, a calibration curve for the oxygen precipitate distribution and transition metal recombination lifetime distribution of the sample was prepared in advance, and the transition metal recombination lifetime was measured by the method of (2) above. If this is collated with the calibration curve, it is not necessary to perform selective etching as in Patent Document 1 to reveal oxygen precipitates, and the oxygen precipitates of the sample can be accurately estimated.
本発明の第１の観点は、(i) ＣＺ法により育成された棒状のシリコン単結晶から切り出されたウェーハをサンプルとして準備する工程と、(ii) サンプル内の酸素析出核を酸素析出物に成長させるために前記サンプルを熱処理する工程と、(iii) 前記熱処理したサンプル表面をＣｕで汚染する工程と、(iv) 前記Ｃｕで汚染したサンプルをサンプル内にＣｕシリサイドが生成しない３００℃を超える第１温度まで昇温して前記Ｃｕをサンプル内に熱拡散させる工程と、(v) 前記Ｃｕをサンプル内に熱拡散させたサンプルを前記第１温度と同じか異なる３００℃を超える第２温度で維持して前記サンプル内の酸素起因の結晶欠陥にＣｕを析出させるとともに前記結晶欠陥に析出させた以外の余剰のＣｕをサンプル表面に拡散させる工程と、(vi) 前記第２温度で維持したサンプルを室温まで冷却する工程と、(vii) 前記室温まで冷却したサンプル表面を洗浄した後、ケミカルエッチング処理する工程と、(viii) 前記ケミカルエッチング処理したサンプルの前記Ｃｕの再結合ライフタイムを測定する工程とを含むシリコンウェーハの検査方法である。 The first aspect of the present invention is: (i) preparing a wafer cut from a rod-shaped silicon single crystal grown by the CZ method as a sample; and (ii) converting oxygen precipitation nuclei in the sample into oxygen precipitates. Heat treating the sample for growth; (iii) contaminating the heat treated sample surface with Cu; and (iv) exceeding 300 ° C. in which Cu silicide is not generated in the sample in the sample contaminated with Cu. A step of raising the temperature to a first temperature and thermally diffusing the Cu into the sample; And (ii) the step of diffusing excess Cu other than that deposited on the crystal defects, and (vi) the second temperature. A step of cooling the sample maintained at room temperature, (vii) a step of chemical etching treatment after washing the sample surface cooled to room temperature, and (viii) a recombination life of the Cu of the sample subjected to the chemical etching treatment. A method for inspecting a silicon wafer including a step of measuring time.
本発明の第２の観点は、第１の観点に基づく発明であって、前記(v)工程及び前記(vi)工程が、前記サンプルを前記第２温度で３０分以上維持し、その後前記第２温度から室温まで放冷するシリコンウェーハの検査方法である。 A second aspect of the present invention is the invention based on the first aspect, wherein the step (v) and the step (vi) maintain the sample at the second temperature for 30 minutes or more, and then This is an inspection method for a silicon wafer that is allowed to cool from two temperatures to room temperature.
本発明の第３の観点は、第１の観点に基づく発明であって、前記(ii)工程の熱処理が、前記サンプル内の酸素析出物サイズが２５ｎｍ以上となるように前記サンプルを熱処理するシリコンウェーハの検査方法である。 A third aspect of the present invention is the invention based on the first aspect, wherein the heat treatment of the step (ii) is performed by heat-treating the sample so that the oxygen precipitate size in the sample is 25 nm or more. This is a wafer inspection method.
本発明の第４の観点は、第１の観点に基づく発明であって、前記(vii)工程のケミカルエッチング処理が、フッ硝酸水溶液を用いて、ＪＩＳＺ８７４１に規定された入射角２０度としたときのサンプル表面の光沢度を７００以上に均一化するエッチングであるリコンウェーハの検査方法である。 A fourth aspect of the present invention is the invention based on the first aspect, wherein the chemical etching treatment in the step (vii) is performed using an aqueous solution of hydrofluoric acid and an incident angle of 20 degrees defined in JISZ8741. This is a method for inspecting a recon wafer, which is etching that makes the gloss of the sample surface uniform to 700 or more.
本発明の第５の観点は、(A) ＣＺ法により育成された棒状のシリコン単結晶から切り出されたウェーハから複数の参照用サンプルを準備する工程と、(B) サンプル内の酸素析出核を酸素析出物に成長させるために前記複数の参照用サンプルを熱処理する工程と、(C) 前記熱処理した複数の参照用サンプルについて赤外散乱トモグラフィにより酸素析出物密度を測定する工程と、(D) 前記熱処理した複数の参照用サンプル表面をＣｕで汚染する工程と、(E) 前記Ｃｕで汚染した複数の参照用サンプルをサンプル内にＣｕシリサイドが生成しない３００℃を超える第１温度まで昇温して前記Ｃｕをサンプル内に熱拡散させる工程と、(F) 前記Ｃｕをサンプル内に熱拡散させた複数の参照用サンプルを前記第１温度と同じか異なる３００℃を超える第２温度で維持して前記サンプル内の酸素起因の結晶欠陥にＣｕを析出させるとともに前記結晶欠陥に析出させた以外の余剰のＣｕをサンプル表面に拡散させる工程と、(G) 前記第２温度で維持した参照用サンプルを室温まで冷却する工程と、(H) 前記室温まで冷却した複数の参照用サンプル表面を洗浄した後、ケミカルエッチング処理する工程と、(I) 前記ケミカルエッチング処理した複数の参照用サンプルの前記Ｃｕの再結合ライフタイムを測定する工程と、(J) 前記(I)工程の測定結果と前記(C)工程の測定結果から、再結合ライフタイムと酸素析出物密度との相関直線からなる検量線を作成する工程と、(K) ＣＺ法により育成された棒状のシリコン単結晶から切り出されたウェーハから検査用サンプルを準備する工程と、(L) 前記検査用サンプルを前記(B)工程と同じ条件で熱処理する工程と、(M) 前記熱処理した検査用サンプル表面を前記(D)工程と同じ条件でＣｕで汚染する工程と、(N) 前記Ｃｕで汚染した検査用サンプルを前記(E)工程と同じ条件で前記Ｃｕをサンプル内に熱拡散させる工程と、(O) 前記Ｃｕをサンプル内に熱拡散させた複数の検査用サンプルを前記(F)工程と同じ第２温度で維持して前記サンプル内の酸素起因の結晶欠陥にＣｕを析出させるとともに前記結晶欠陥に析出させた以外の余剰のＣｕをサンプル表面に拡散させる工程と、(P) 前記第２温度で維持した検査用サンプルを室温まで冷却する工程と、(Q) 前記室温まで冷却した検査用サンプル表面を洗浄した後、ケミカルエッチング処理する工程と、(R) 前記ケミカルエッチング処理した検査用サンプルの前記Ｃｕの再結合ライフタイムを測定する工程と、(S) 前記(R)工程の測定結果を前記(J)工程で作成した検量線に照合することにより、前記検査用サンプルの酸素析出物密度を推定する工程とを含むシリコンウェーハの検査方法である。 According to a fifth aspect of the present invention, (A) a step of preparing a plurality of reference samples from a wafer cut from a rod-shaped silicon single crystal grown by the CZ method, and (B) oxygen precipitation nuclei in the sample. Heat treating the plurality of reference samples to grow into oxygen precipitates, and (C) measuring oxygen precipitate density by infrared scattering tomography for the heat treated reference samples, and (D And (E) raising the temperature of the plurality of reference samples contaminated with Cu to a first temperature exceeding 300 ° C. at which Cu silicide is not generated in the sample. And a step of thermally diffusing the Cu into the sample, and (F) a second temperature exceeding 300 ° C., which is equal to or different from the first temperature, for a plurality of reference samples in which the Cu is thermally diffused into the sample. Maintaining and precipitating Cu to crystal defects due to oxygen in the sample and diffusing excess Cu other than the crystal defects to the sample surface; and (G) reference maintained at the second temperature. Cooling the sample to room temperature, (H) cleaning the surfaces of the plurality of reference samples cooled to room temperature, and then chemically etching, and (I) a plurality of the reference samples subjected to chemical etching. The step of measuring the recombination lifetime of Cu, and (J) from the measurement result of the step (I) and the measurement result of the step (C), comprising a correlation line between the recombination lifetime and the oxygen precipitate density. A step of preparing a calibration curve, (K) a step of preparing a sample for inspection from a wafer cut from a rod-shaped silicon single crystal grown by the CZ method, and (L) the sample for inspection described above (B) (M) the step of contaminating the heat-treated inspection sample surface with Cu under the same conditions as in the step (D), and (N) the inspection sample contaminated with Cu. (E) the step of thermally diffusing the Cu into the sample under the same conditions as in the step (E), and (O) a plurality of test samples in which the Cu is thermally diffused into the sample at the same second temperature as the step (F) Maintaining and precipitating Cu on crystal defects caused by oxygen in the sample and diffusing excess Cu other than the crystal defects on the sample surface; and (P) an inspection maintained at the second temperature. A step of cooling the sample to room temperature, (Q) a step of cleaning the surface of the sample for inspection that has been cooled to room temperature, and then performing a chemical etching treatment; Combined life And (S) the step of estimating the oxygen precipitate density of the test sample by collating the measurement result of the step (R) with the calibration curve created in the step (J). It is an inspection method of a silicon wafer containing.
本発明の第６の観点は、第５の観点に基づく発明であって、前記(F)工程及び前記(G)工程、又は前記(O)工程及び前記(P)工程が、前記サンプルを前記第２温度で３０分以上維持し、その後前記第２温度から室温まで放冷するシリコンウェーハの検査方法である。 A sixth aspect of the present invention is the invention based on the fifth aspect , wherein the step (F) and the step (G) or the step (O) and the step (P) This is a method for inspecting a silicon wafer that is maintained at a second temperature for 30 minutes or more and then allowed to cool from the second temperature to room temperature.
本発明の第７の観点は、第５の観点に基づく発明であって、前記(B)工程又は前記(L)工程の熱処理が前記参照用又は前記検査用サンプル内の酸素析出物サイズが２５ｎｍ以上となるように前記サンプルを熱処理するシリコンウェーハの検査方法である。 A seventh aspect of the present invention is the invention based on the fifth aspect , wherein the heat treatment in the step (B) or the step (L) is performed so that the oxygen precipitate size in the reference or inspection sample is 25 nm. This is a silicon wafer inspection method in which the sample is heat-treated as described above.
本発明の第８の観点は、第５の観点に基づく発明であって、前記(H)工程又は前記(Q)工程のケミカルエッチング処理が、フッ硝酸水溶液を用いて、ＪＩＳＺ８７４１に規定された入射角２０度としたときのサンプル表面の光沢度を７００以上に均一化するエッチングであるシリコンウェーハの検査方法である。 An eighth aspect of the present invention is the invention based on the fifth aspect , in which the chemical etching treatment in the step (H) or the step (Q) is performed according to JISZ8741 using a hydrofluoric acid aqueous solution. This is an inspection method for a silicon wafer, which is an etching that makes the gloss of the sample surface uniform to 700 or more when the angle is 20 degrees.
本発明の第９の観点は、第５ないし第８のいずれかの観点に基づく方法で前記検査用サンプルの酸素析出物密度を推定した結果に基づいて、ＣＺ法によるシリコン単結晶の引上げ条件を決定し、前記決定された引上げ条件で単結晶内の酸素析出物密度を制御してシリコン単結晶を育成する方法である。 According to a ninth aspect of the present invention, there is provided a condition for pulling the silicon single crystal by the CZ method based on the result of estimating the oxygen precipitate density of the test sample by the method based on any one of the fifth to eighth aspects. In this method, the silicon single crystal is grown by controlling the oxygen precipitate density in the single crystal under the determined pulling condition.
本発明の第１０の観点は、第５ないし第８のいずれかの観点に基づく方法で前記検査用サンプルの酸素析出物密度を推定した結果に基づいて、前記検査用サンプルを準備したシリコン単結晶から切り出されたシリコンウェーハの品質を判定する方法である。 According to a tenth aspect of the present invention, there is provided a silicon single crystal in which the inspection sample is prepared based on a result of estimating an oxygen precipitate density of the inspection sample by a method based on any one of the fifth to eighth aspects. This is a method for judging the quality of a silicon wafer cut out from a wafer.
本発明の第１の観点の検査方法では、特許文献１の評価方法がＣｕ又はＮｉを熱処理によりサンプル内部に拡散させた後にサンプルを急冷して、過飽和なＣｕ又はＮｉも結晶中に取り残すのに対して、熱処理したサンプル表面をＣｕで汚染したシリコンウェーハのサンプルをサンプル内にＣｕシリサイドが生成しない３００℃を超える第１温度まで昇温することによりＣｕをサンプル内に熱拡散させた後で、サンプルを前記第１温度と同じか異なる３００℃を超える第２温度で維持するため、サンプル内の酸素起因の結晶欠陥にＣｕを析出させるとともに前記結晶欠陥に析出させた以外の余剰のＣｕをサンプル表面に拡散させることができる。このサンプル表面をケミカルエッチング処理してサンプル表面のＣｕを除去すれば、サンプル内には酸素析出物にＣｕのデコレーションした領域のみにすることができる。こうしたサンプルの銅の再結合ライフタイムは、外乱のない正確な値とすることができる。またケミカルエッチング処理をすることによりサンプルの表面粗さを小さくし、再結合ライフタイムを正確に測定することができる。 In the inspection method according to the first aspect of the present invention, the evaluation method of Patent Document 1 uses Cu or Ni to diffuse into the sample by heat treatment, and then rapidly cools the sample to leave supersaturated Cu or Ni in the crystal. On the other hand, after heat-diffusing Cu into the sample by raising the temperature of the heat-treated sample surface to a first temperature exceeding 300 ° C. at which Cu silicide is not generated in the sample, the sample of the silicon wafer contaminated with Cu is obtained. In order to maintain the sample at a second temperature exceeding 300 ° C., which is the same as or different from the first temperature, Cu is precipitated in oxygen-induced crystal defects in the sample and surplus Cu other than the crystal defects is sampled. Can diffuse to the surface. If the sample surface is chemically etched to remove Cu on the sample surface, only oxygen-deposited regions of Cu are decorated in the sample. The copper recombination lifetime of these samples can be accurate without disturbance. In addition, the chemical etching treatment can reduce the surface roughness of the sample and accurately measure the recombination lifetime.
本発明の第２の観点の検査方法では、前記(v)工程及び前記(vi)工程が、前記サンプルを前記第２温度で３０分以上維持し、その後前記第２温度から室温まで放冷するため、サンプル内の酸素起因の結晶欠陥にＣｕを析出させるとともに前記結晶欠陥に析出させた以外の余剰のＣｕをサンプル表面に拡散させ、これによりサンプル内に取り残されるＣｕの量が低減される。 In the inspection method according to the second aspect of the present invention, in the step (v) and the step (vi), the sample is maintained at the second temperature for 30 minutes or more and then allowed to cool from the second temperature to room temperature. Therefore, Cu is precipitated in oxygen-induced crystal defects in the sample, and excess Cu other than the crystal defects is diffused on the sample surface, thereby reducing the amount of Cu left in the sample.
本発明の第３の観点の検査方法では、前記(ii)工程の熱処理が、前記サンプル内の酸素析出物サイズが２５ｎｍ以上となるように前記サンプルを熱処理するため、Ｃｕを的確にサンプル内の酸素析出物にデコレーションさせることができる。 In the inspection method of the third aspect of the present invention, since the heat treatment in the step (ii) heat-treats the sample so that the oxygen precipitate size in the sample is 25 nm or more, Cu is accurately contained in the sample. The oxygen precipitate can be decorated.
本発明の第４の観点の検査方法では、前記(vii)工程のケミカルエッチング処理が、フッ硝酸水溶液を用いて、ＪＩＳＺ８７４１に規定された入射角２０度としたときのサンプル表面の光沢度を７００以上に均一化することにより、サンプルの表面粗さが小さくなり、Ｃｕの再結合ライフタイムを高精度に測定することができる。 In the inspection method according to the fourth aspect of the present invention, the glossiness of the sample surface is 700 when the chemical etching treatment in the step (vii) uses an aqueous solution of hydrofluoric acid and has an incident angle of 20 degrees defined in JISZ8741. By homogenizing as described above, the surface roughness of the sample is reduced, and the recombination lifetime of Cu can be measured with high accuracy.
本発明の第５の観点の検査方法では、参照用サンプルを用いて、サンプルの酸素析出物分布とＣｕの再結合ライフタイム分布の検量線を予め作成しておき、第１の観点の方法で検査用サンプルのＣｕの再結合ライフタイムを測定し、これを上記検量線に照合すれば、特許文献１のような選択エッチングを行って酸素析出物を顕在化させる必要はなく、また高価な赤外散乱トモグラフィ装置で長時間費やすことなく、検査用サンプルの酸素析出物を高精度で簡易に推定することができる。 In the inspection method of the fifth aspect of the present invention, using the reference sample, a calibration curve of the oxygen precipitate distribution of the sample and the recombination lifetime distribution of Cu is prepared in advance, and the method of the first aspect is used. If the recombination lifetime of Cu in the sample for inspection is measured and collated with the calibration curve, it is not necessary to perform selective etching as in Patent Document 1 to reveal oxygen precipitates, and expensive red Without spending a long time with the outside scattering tomography apparatus, it is possible to easily estimate the oxygen precipitates of the test sample with high accuracy.
本発明の第６の観点の検査方法では、前記(F)工程及び前記(G)工程、又は前記(O)工程及び前記(P)工程が、前記サンプルを前記第２温度で３０分以上維持し、その後前記第２温度から室温まで放冷するため、サンプル内の酸素起因の結晶欠陥にＣｕを析出させるとともに前記結晶欠陥に析出させた以外の余剰のＣｕをサンプル表面に拡散させ、これによりサンプル内に取り残されるＣｕの量が低減される。 In the inspection method of the sixth aspect of the present invention, the step (F) and the step (G), or the step (O) and the step (P) maintain the sample at the second temperature for 30 minutes or more. Then, in order to cool from the second temperature to room temperature, Cu is precipitated in the crystal defects due to oxygen in the sample, and excess Cu other than the crystal defects is diffused on the sample surface, thereby The amount of Cu left in the sample is reduced.
本発明の第７の観点の検査方法では、前記(B)工程又は前記(L)工程の熱処理が、前記サンプル内の酸素析出物サイズが２５ｎｍ以上となるように前記サンプルを熱処理するため、Ｃｕを的確にサンプル内の酸素析出物にデコレーションさせることができる。 In the inspection method according to the seventh aspect of the present invention, the heat treatment of the step (B) or the step (L) heats the sample so that the oxygen precipitate size in the sample is 25 nm or more. Can be accurately decorated with oxygen precipitates in the sample.
本発明の第８の観点の検査方法では、前記(H)工程又は前記(Q)工程のケミカルエッチング処理が、フッ硝酸水溶液を用いて、ＪＩＳＺ８７４１に規定された入射角２０度としたときのサンプル表面の光沢度を７００以上に均一化することにより、サンプルの表面粗さが小さくなり、Ｃｕの再結合ライフタイムを高精度に測定することができる。 In the inspection method according to the eighth aspect of the present invention, a sample when the chemical etching treatment in the step (H) or the step (Q) is performed using an aqueous hydrofluoric acid solution and an incident angle of 20 degrees defined in JISZ8741. By uniformizing the glossiness of the surface to 700 or more, the surface roughness of the sample is reduced, and the recombination lifetime of Cu can be measured with high accuracy.
本発明の第９の観点の検査方法では、第５ないし第８のいずれかの観点に基づく方法で前記検査用サンプルの酸素析出物密度を推定した結果に基づいて、ＣＺ法によるシリコン単結晶の引上げ条件を決定し、前記決定された引上げ条件で単結晶内の酸素析出物密度を制御すれば、ＣＯＰ及び転移クラスタの欠陥がないシリコン単結晶を育成することができる。 In the inspection method of the ninth aspect of the present invention, based on the result of estimating the oxygen precipitate density of the inspection sample by the method based on any one of the fifth to eighth aspects, If the pulling conditions are determined and the oxygen precipitate density in the single crystal is controlled under the determined pulling conditions, a silicon single crystal free from defects in COP and transition clusters can be grown.
本発明の第１０の観点の検査方法では、第５ないし第８のいずれかの観点に基づく方法で前記検査用サンプルの酸素析出物密度を推定した結果に基づいて、前記検査用サンプルを準備したシリコン単結晶から切り出されたシリコンウェーハの品質を判定することができる。 In the inspection method of the tenth aspect of the present invention, the inspection sample is prepared based on the result of estimating the oxygen precipitate density of the inspection sample by the method based on any one of the fifth to eighth aspects. The quality of the silicon wafer cut out from the silicon single crystal can be determined.
以下、本発明のシリコンウェーハの検査方法の実施形態について、詳しく説明する。 Hereinafter, embodiments of the silicon wafer inspection method of the present invention will be described in detail.
＜第1実施形態＞
先ず、本発明の第１実施形態のシリコンウェーハの検査方法を工程順に説明する。図１（i）に示すように、先ずＣＺ法により育成された棒状のシリコン単結晶から切り出されたウェーハをサンプルとして準備する。次いで、図１（ii）に示すように、サンプル内の酸素析出核を酸素析出物に成長させるためにこのサンプルを熱処理する。熱処理は、７００〜１０００℃で４〜１６時間、乾燥酸素雰囲気で熱処理して、サンプル内の酸素析出物サイズが２５ｎｍ以上となるようにすることが好ましい。こうすることにより、Ｃｕを的確にサンプル内の酸素析出物にデコレーションさせることができる。次に、図１（iii）に示すように、熱処理したサンプルの表面をＣｕで汚染する。Ｃｕ汚染は、一般的なＣｕデコレーションと同様に行うことができる。具体的には、例えばサンプルをＣｕ含有溶液中に浸漬した後、この溶液から取り出し所定時間自然乾燥等により乾燥させる。このＣｕ含有溶液としては、硝酸銅水溶液や硝酸銅とフッ酸（ＨＦ）との混合溶液等を用いることができる。この溶液中の銅濃度は、Ｐv領域及びＰi領域を均一にデコレーションする観点からは、３×１０２０ａｔｏｍｓ／ｃｍ３以上とすることが好ましい。銅含有溶液の銅濃度が高いほど均一なデコレーションの観点からは好ましく、例えば、溶解度上限まで銅を含有する溶液を使用することも可能である。
<First Embodiment>
First, the silicon wafer inspection method according to the first embodiment of the present invention will be described in the order of steps. As shown in FIG. 1 (i), a wafer cut from a rod-shaped silicon single crystal grown by the CZ method is prepared as a sample. Next, as shown in FIG. 1 (ii), this sample is heat-treated in order to grow oxygen precipitation nuclei in the sample into oxygen precipitates. The heat treatment is preferably performed at 700 to 1000 ° C. for 4 to 16 hours in a dry oxygen atmosphere so that the oxygen precipitate size in the sample is 25 nm or more. By doing so, Cu can be accurately decorated to oxygen precipitates in the sample. Next, as shown in FIG. 1 (iii), the surface of the heat-treated sample is contaminated with Cu. Cu contamination can be performed in the same manner as general Cu decoration. Specifically, for example, after immersing a sample in a Cu-containing solution, the sample is taken out from the solution and dried by natural drying or the like for a predetermined time. As this Cu-containing solution, a copper nitrate aqueous solution, a mixed solution of copper nitrate and hydrofluoric acid (HF), or the like can be used. The copper concentration in the solution is preferably 3 × 10 20 atoms / cm 3 or more from the viewpoint of uniformly decorating the Pv region and the Pi region. The higher the copper concentration of the copper-containing solution, the more preferable from the viewpoint of uniform decoration. For example, a solution containing copper up to the upper limit of solubility can be used.
次に、図１（iv）に示すように、Ｃｕ汚染後のサンプルに対して、Ｃｕの拡散熱処理を行う。具体的には、Ｃｕで汚染したサンプルをサンプル内にＣｕシリサイドが生成しない３００℃を超える第１温度まで昇温してＣｕをサンプル内に熱拡散させる。この第１温度は、サンプルに対するＣｕの固溶度が１×１０１６ａｔｏｍｓ／ｃｍ３以上になる温度であることが好ましく、サンプル等に熱的負荷を過剰に付与しないように、第１温度の上限値は７００℃が好ましい。続いて、図１（v）に示すように、この熱拡散させたサンプルを第２温度で維持する。具体的には、この第２温度は、サンプル内にＣｕシリサイドが生成しない３００℃を超える温度であって、前記第１温度と同じでも、異なってもよい。この第２温度は、サンプルに対するＣｕの固溶度が５×１０１２ａｔｏｍｓ／ｃｍ３以下になる温度であることが好ましい。以下の表１に、温度に応じたＣｕのシリコン中の拡散距離及び固溶度を示す。Ｃｕの固溶度が１×１０１６ａｔｏｍｓ／ｃｍ３以上になる温度とは、６９２℃以上の温度であり、Ｃｕの固溶度が５×１０１２ａｔｏｍｓ／ｃｍ３以下になる温度とは、その下限はシリコン中でＣｕがＣｕシリサイドを形成しない３００℃を超える温度であり、その上限は４０２℃である。 Next, as shown in FIG. 1 (iv), Cu diffusion heat treatment is performed on the sample after Cu contamination. Specifically, the sample contaminated with Cu is heated to a first temperature exceeding 300 ° C. at which Cu silicide is not generated in the sample, and Cu is thermally diffused into the sample. This first temperature is preferably a temperature at which the solid solubility of Cu in the sample is 1 × 10 16 atoms / cm 3 or more, and the first temperature is set so as not to excessively apply a thermal load to the sample or the like. The upper limit is preferably 700 ° C. Subsequently, as shown in FIG. 1 (v), the thermally diffused sample is maintained at the second temperature. Specifically, the second temperature is a temperature exceeding 300 ° C. at which Cu silicide is not generated in the sample, and may be the same as or different from the first temperature. This second temperature is preferably a temperature at which the solid solubility of Cu in the sample is 5 × 10 12 atoms / cm 3 or less. Table 1 below shows the diffusion distance and solid solubility of Cu in silicon according to temperature. The temperature at which the solid solubility of Cu is 1 × 10 16 atoms / cm 3 or higher is 692 ° C. or higher, and the temperature at which the solid solubility of Cu is 5 × 10 12 atoms / cm 3 or lower is The lower limit is a temperature exceeding 300 ° C. at which Cu does not form Cu silicide in silicon, and the upper limit is 402 ° C.
前記(v)工程及び前記(vi)工程における方法は、サンプルを前記第２温度で３０分以上維持し、その後前記第２温度から室温まで放冷する方法である。ここで、下限の維持時間を３０分とするのは、例えば第２温度を３００℃、サンプル（シリコンウェーハ）の厚みを７５０μｍと仮定すれば、３０分間でサンプル内全域の酸素起因の結晶欠陥にＣｕを析出させるのに十分であるからである。
上記方法で、維持時間が３０分未満の場合、Ｃｕがサンプル内の酸素起因の結晶欠陥に十分に析出しない恐れがある。上記方法により、サンプル内の酸素起因の結晶欠陥にＣｕを析出させるとともに結晶欠陥に析出させた以外の過飽和で余剰のＣｕをサンプル表面に拡散させて、これによりサンプル内に取り残されるＣｕの量を低減することができる。
The method in the step (v) and the step (vi) is a method in which the sample is maintained at the second temperature for 30 minutes or more and then allowed to cool from the second temperature to room temperature. Here, if the second temperature is set to 300 ° C. and the thickness of the sample (silicon wafer) is assumed to be 750 μm, for example, the lower limit maintenance time is set to 30 minutes. This is because it is sufficient to precipitate Cu .
In the above method, when the maintenance time is less than 30 minutes, Cu may not be sufficiently deposited on crystal defects caused by oxygen in the sample . By the above method, Cu is precipitated on oxygen-induced crystal defects in the sample, and excess Cu other than that precipitated on the crystal defects is diffused to the sample surface, whereby the amount of Cu left in the sample is reduced. Can be reduced.
次に、図１（vii）に示すように、室温まで冷却したサンプル表面を洗浄した後、ケミカルエッチング処理する。具体的には、サンプルを純水で超音波洗浄した後、フッ硝酸水溶液を用いて、ＪＩＳＺ８７４１に規定された入射角２０度としたときのサンプル表面の光沢度を７００以上に均一化する。こうすることにより、サンプルの表面粗さが小さくなり、Ｃｕの再結合ライフタイムを高精度に測定することができる。続いて、図１（viii）に示すように、ケミカルエッチング処理したサンプルのＣｕの再結合ライフタイムを測定する。この測定方法としては、光で励起される少数キャリアのライフタイムを測定するμ−ＰＣＤ法が簡便で測定精度が高いため、好適である。 Next, as shown in FIG. 1 (vii), the sample surface cooled to room temperature is washed and then subjected to chemical etching. Specifically, after the sample is ultrasonically cleaned with pure water, the aqueous gloss of nitric acid is used to equalize the gloss of the sample surface to 700 or more when the incident angle is 20 degrees as defined in JISZ8741. By doing so, the surface roughness of the sample is reduced, and the recombination lifetime of Cu can be measured with high accuracy. Subsequently, as shown in FIG. 1 (viii), the Cu recombination lifetime of the chemically etched sample is measured. As this measurement method, the μ-PCD method for measuring the lifetime of minority carriers excited by light is convenient and has high measurement accuracy, and thus is preferable.
＜第２実施形態＞
次に、本発明の第２実施形態のシリコンウェーハの検査方法を工程順に説明する。
〔参照用サンプルの準備から検量線の作成まで〕
図２（Ａ）に示すように、先ずＣＺ法により育成された棒状のシリコン単結晶から切り出された複数のウェーハを参照用サンプルとして準備する。次いで、図２（Ｂ）に示すように、第１実施形態と同様のこれらの参照用サンプルの熱処理を行う。 次に、図２（Ｃ）に示すように、熱処理した複数の参照用サンプルの酸素析出物密度と分布を測定する。この酸素析出物密度と分布の測定は、赤外散乱（ＩＲ）トモグラフィ（レイテックス社製ＭＯ−４４１）でＬＳＴＤ（Laser Scattering Tomograph Defects）密度と分布を測定することが測定精度が高いため、好ましい。次に、図２（Ｄ）に示すように、熱処理した参照用サンプルの表面をＣｕで汚染する。Ｃｕ汚染は、第１実施形態と同様に行う。
Second Embodiment
Next, the silicon wafer inspection method according to the second embodiment of the present invention will be described in the order of steps.
[From preparation of reference sample to creation of calibration curve]
As shown in FIG. 2A, first, a plurality of wafers cut out from a rod-shaped silicon single crystal grown by the CZ method are prepared as reference samples. Next, as shown in FIG. 2B, these reference samples are heat-treated as in the first embodiment. Next, as shown in FIG. 2C, the oxygen precipitate density and distribution of the plurality of heat-treated reference samples are measured. Since the measurement of the oxygen precipitate density and distribution is high in measuring accuracy by measuring LSTD (Laser Scattering Tomograph Defects) density and distribution by infrared scattering (IR) tomography (MO-441 manufactured by Raytex), preferable. Next, as shown in FIG. 2D, the surface of the heat-treated reference sample is contaminated with Cu. Cu contamination is performed in the same manner as in the first embodiment.
次に、図２（Ｅ）〜（Ｇ）に示すように、Ｃｕ汚染後の参照用サンプルに対して、第１実施形態と同様に、第１温度までの昇温によるＣｕの拡散熱処理、第２温度での維持、室温冷却を行う。次に、図２（Ｈ）及び（Ｉ）に示すように、第１実施形態と同様に、室温まで冷却した参照用サンプルの表面を洗浄した後、ケミカルエッチング処理し、続いて参照用サンプルのＣｕの再結合ライフタイムを測定する。続いて、図２（Ｊ）に示すように、参照用サンプルに関して、よこ軸に得られたＣｕの再結合ライフタイムを、たて軸に上述した熱処理後に測定したＬＳＴＤ密度（酸素析出物密度）をプロットし、複数の再結合ライフタイムの値と複数の酸素析出物密度の値から相関直線を作成し、これを検量線とする。 Next, as shown in FIGS. 2 (E) to 2 (G), a Cu diffusion heat treatment by heating up to the first temperature is performed on the reference sample after Cu contamination, as in the first embodiment, Maintain at 2 temperatures and cool to room temperature. Next, as shown in FIGS. 2 (H) and (I), as in the first embodiment, the surface of the reference sample cooled to room temperature is washed and then subjected to chemical etching, followed by the reference sample. The recombination lifetime of Cu is measured. Subsequently, as shown in FIG. 2 (J), with respect to the reference sample, the recombination lifetime of Cu obtained on the horizontal axis was measured after the above-described heat treatment on the vertical axis (LSTD density (oxygen precipitate density)). Is plotted, a correlation line is created from a plurality of recombination lifetime values and a plurality of oxygen precipitate density values, and this is used as a calibration curve.
〔検査用サンプルの準備から酸素析出物密度の推定まで〕
図２（Ｋ）〜（Ｒ）に示すように、検査用サンプルを準備した後、検査用サンプルの酸素析出物密度を測定することなく、検査用サンプルに対して、参照用サンプルと同様に、熱処理、Ｃｕ汚染、第１温度までの昇温によるＣｕ拡散熱処理、第２温度での維持、室温冷却、ケミカルエッチング処理、Ｃｕの再結合ライフタイム測定を行う。続いて、図２（Ｓ）に示すように、得られた再結合ライフタイムの値を上述した検量線に照合して、検査用サンプルの酸素析出物密度を推定する。この結果、選択エッチングを行って酸素析出物を顕在化させる必要はなく、また高価な赤外散乱トモグラフィ装置で長時間費やすことなく、検査用サンプルの酸素析出物を高精度で簡易に識別することができる。
[From preparation of test sample to estimation of oxygen precipitate density]
As shown in FIGS. 2 (K) to (R), after preparing the test sample, without measuring the oxygen precipitate density of the test sample, the test sample is similar to the reference sample, Heat treatment, Cu contamination, Cu diffusion heat treatment by heating up to the first temperature, maintenance at the second temperature, room temperature cooling, chemical etching treatment, and Cu recombination lifetime measurement are performed. Subsequently, as shown in FIG. 2 (S), the obtained recombination lifetime value is collated with the calibration curve described above to estimate the oxygen precipitate density of the test sample. As a result, it is not necessary to perform selective etching to reveal oxygen precipitates, and the oxygen precipitates in the test sample can be easily and accurately identified without spending a long time with an expensive infrared scattering tomography apparatus. be able to.
次に本発明の実施例を比較例とともに詳しく説明する。 Next, examples of the present invention will be described in detail together with comparative examples.
＜実施例１＞
図２（Ａ）に示すように、ＣＺ法によりＣＯＰや転移クラスタが存在しないＰi領域及びＰv領域を含むように引上げられた棒状のシリコン単結晶から１０枚のシリコンウェーハを切り出した。切り出したウェーハは厚さ１ｍｍ、直径３００ｍｍ、抵抗値１０Ω・ｃｍ、酸素濃度１０×１０１７ａｔｏｍｓ／ｃｍ３（旧ＡＳＴＭ）であった。
<Example 1>
As shown in FIG. 2A, ten silicon wafers were cut out from a rod-like silicon single crystal pulled to include a Pi region and a Pv region where COP and transition clusters do not exist by CZ method. The cut out wafer had a thickness of 1 mm, a diameter of 300 mm, a resistance value of 10 Ω · cm, and an oxygen concentration of 10 × 10 17 atoms / cm 3 (former ASTM).
これらのウェーハを参照用サンプルとして、図２（Ｂ）に示すように、参照用サンプル内の酸素析出物サイズを２０ｎｍ以上にするために、これらの参照用サンプルを１０００℃、１６時間、乾燥酸素雰囲気で熱処理した。図２（Ｃ）に示すように、熱処理した１枚のサンプルを劈開し、劈開面における参照用サンプルのＬＳＴＤ（Laser Scattering Tomograph Defects）密度を赤外散乱（ＩＲ）トモグラフィ（レイテックス社製ＭＯ−４４１）で測定することにより、参照用サンプルの酸素析出物密度と分布を求めた。 Using these wafers as reference samples, as shown in FIG. 2 (B), in order to make the oxygen precipitate size in the reference sample 20 nm or more, these reference samples were dried oxygen at 1000 ° C. for 16 hours. Heat-treated in the atmosphere. As shown in FIG. 2C, one heat-treated sample is cleaved, and the LSTD (Laser Scattering Tomograph Defects) density of the reference sample on the cleavage plane is determined by infrared scattering (IR) tomography (MO manufactured by Raytex). -441), the oxygen precipitate density and distribution of the reference sample were determined.
次に、図２（Ｄ）に示すように、水１リットルに硝酸銅(II)三水和物Ｃｕ(ＮＯ３)２・３Ｈ２Ｏ（硝酸銅含有割合９９質量％）１００ｇを溶解した硝酸銅水溶液をＣｕデコレーション用の銅含有溶液として調製し、この硝酸銅水溶液を上記熱処理した上記参照用サンプルを硝酸銅水溶液に浸漬させた後、サンプルを自然乾燥させることにより、参照用サンプルの表面をＣｕで汚染した。Ｃｕの汚染量は１．７×１０１５ａｔｏｍｓ／ｃｍ２以上であった。 Next, as shown in FIG. 2 (D), nitric acid in which 100 g of copper (II) nitrate trihydrate Cu (NO 3 ) 2 .3H 2 O (copper nitrate content 99 mass%) was dissolved in 1 liter of water. A copper aqueous solution was prepared as a copper-containing solution for Cu decoration, and after the above heat-treated copper nitrate aqueous solution was immersed in the copper nitrate aqueous solution, the sample was allowed to air dry so that the surface of the reference sample was Contaminated with Cu. The contamination amount of Cu was 1.7 × 10 15 atoms / cm 2 or more.
次に、図２（Ｅ）に示すように、Ｃｕの拡散熱処理を行った。具体的には、Ｃｕで汚染した参照用サンプルを大気雰囲気下の電気炉に入れ、１０℃／分の速度で昇温し、７００℃で５分間維持した。続いて、図２（Ｆ）に示すように、これらの参照用サンプルを降温した。具体的には、参照用サンプルを４００℃に維持された別の電気炉に入れ、そこで４５分間維持した。続いて、図２（Ｇ）に示すように、電気炉から参照用サンプルを取り出し、放置することによって、室温まで５０℃／分の速度で急冷した。 Next, as shown in FIG. 2E, a diffusion heat treatment of Cu was performed. Specifically, a reference sample contaminated with Cu was placed in an electric furnace in an air atmosphere, heated at a rate of 10 ° C./min, and maintained at 700 ° C. for 5 minutes. Subsequently, as shown in FIG. 2F, the temperature of these reference samples was lowered. Specifically, the reference sample was placed in another electric furnace maintained at 400 ° C. and maintained there for 45 minutes. Subsequently, as shown in FIG. 2 (G), the reference sample was taken out from the electric furnace and left to stand, thereby rapidly cooling to room temperature at a rate of 50 ° C./min.
次に、図２（Ｈ）に示すように、上記参照用サンプルをケミカルエッチング処理を行った。具体的には、参照用サンプルを純水で超音波洗浄した後、ＨＦ（５０質量％）：ＨＮＯ３（４８質量％）＝１：５（体積比）の室温のエッチング液で５分間ミラーエッチングし、次いで１０分間の水洗リンスを行った。続いて、図２（Ｉ）に示すように、参照用サンプルのＣｕの再結合ライフタイムをμ−ＰＣＤ法により測定した。図２（Ｊ）に示すように、参照用サンプルに関して、よこ軸に得られたＣｕの再結合ライフタイムを、たて軸に上述した熱処理後に測定したＬＳＴＤ密度（酸素析出物密度）をプロットし、５０個以上の再結合ライフタイムの値と５０個以上の酸素析出物密度の値から相関直線を作成し、これを検量線αとした。この検量線αを図３に示す。この検量線のＲ２は０．９１２８であり、高い相関関係を示した。 Next, as shown in FIG. 2H, the reference sample was subjected to chemical etching. Specifically, after ultrasonically cleaning a reference sample with pure water, mirror etching is performed for 5 minutes with an etching solution at room temperature of HF (50 mass%): HNO 3 (48 mass%) = 1: 5 (volume ratio). Then, rinse with water for 10 minutes was performed. Subsequently, as shown in FIG. 2I, the Cu recombination lifetime of the reference sample was measured by the μ-PCD method. As shown in FIG. 2 (J), for the reference sample, the recombination lifetime of Cu obtained on the horizontal axis is plotted with the LSTD density (oxygen precipitate density) measured after the heat treatment described above on the vertical axis. A correlation line was created from 50 or more recombination lifetime values and 50 or more oxygen precipitate density values, and this was used as a calibration curve α. This calibration curve α is shown in FIG. R 2 of this calibration curve was 0.9128, indicating a high correlation.
図２（Ｋ））〜（Ｒ）に示すように、検査用サンプルを準備した後、検査用サンプルの酸素析出物密度を測定することなく、参照用サンプルと同様に検査用サンプルを処理して検査用サンプルのＣｕの再結合ライフタイムをμ−ＰＣＤ法により測定した。具体的には、参照用サンプルを準備したシリコン単結晶とは別に、ＣＺ法によりＣＯＰや転移クラスタが存在しないＰi領域及びＰv領域を含むように引上げられた棒状のシリコン単結晶からシリコンウェーハ（厚さ１ｍｍ、直径３００ｍｍ、抵抗値１０Ω・ｃｍ、酸素濃度１０×１０１７ａｔｏｍｓ／ｃｍ３（旧ＡＳＴＭ））を切り出し、このウェーハを検査用サンプルとした。この検査用サンプルに対して、参照用サンプルと同様に、熱処理、Ｃｕ汚染、第１温度までの昇温によるＣｕ拡散熱処理、第２温度での維持、室温冷却、ケミカルエッチング処理、Ｃｕの再結合ライフタイム測定を行った。 As shown in FIGS. 2 (K) to (R), after preparing the test sample, the test sample is processed in the same manner as the reference sample without measuring the oxygen precipitate density of the test sample. The recombination lifetime of Cu of the test sample was measured by the μ-PCD method. Specifically, apart from the silicon single crystal for which the reference sample is prepared, a silicon wafer (thickness) is obtained from a rod-like silicon single crystal pulled by CZ method so as to include a Pi region and a Pv region where no COP or transition cluster exists. A thickness of 1 mm, a diameter of 300 mm, a resistance value of 10 Ω · cm, an oxygen concentration of 10 × 10 17 atoms / cm 3 (former ASTM) was cut out, and this wafer was used as an inspection sample. For this test sample, as with the reference sample, heat treatment, Cu contamination, Cu diffusion heat treatment by raising the temperature to the first temperature, maintenance at the second temperature, room temperature cooling, chemical etching treatment, Cu recombination Lifetime measurement was performed.
図２（Ｓ）に示すように、得られた再結合ライフタイムの値を図３に示す検量線αに照合して、検査用サンプルのＬＳＴＤ密度（酸素析出物密度）を推定した。この検査用サンプルについて、確認のため、赤外散乱トモグラフィ（レイテックス社製ＭＯ−４４１）でＬＳＴＤ密度を測定したところ、図３のたて軸の値とほぼ同一の値を示した。 As shown in FIG. 2 (S), the value of the obtained recombination lifetime was collated with the calibration curve α shown in FIG. 3 to estimate the LSTD density (oxygen precipitate density) of the test sample. For confirmation, the LSTD density of this test sample was measured by infrared scattering tomography (MO-441 manufactured by Raytex Co., Ltd.), and the value was almost the same as the value of the vertical axis in FIG.
＜実施例２＞
図２（Ｅ）に示した実施例１のＣｕの拡散熱処理を以下に記載するように変更した。即ち、参照用サンプルを７００℃で５分間維持した後、同一の電気炉内で３００℃まで３℃／分の速度で徐冷した。その後、図２（Ｇ）に示すように、電気炉から参照用サンプルを取り出し、放置することによって、室温まで５０℃／分の速度で急冷した。それ以外は、図２（Ａ）〜（Ｄ）に示すように、実施例１と同様にして、参照用サンプルを準備し、ＩＲトモグラフィにより参照用サンプルの酸素析出物密度を測定し、参照用サンプルをＣｕで汚染した。
<Example 2>
The Cu diffusion heat treatment of Example 1 shown in FIG. 2 (E) was changed as described below. That is, after maintaining the reference sample at 700 ° C. for 5 minutes, it was gradually cooled to 300 ° C. at a rate of 3 ° C./min in the same electric furnace. Thereafter, as shown in FIG. 2 (G), the reference sample was taken out from the electric furnace and left to stand, thereby rapidly cooling to room temperature at a rate of 50 ° C./min. Otherwise, as shown in FIGS. 2 (A) to (D), a reference sample was prepared in the same manner as in Example 1, and the oxygen precipitate density of the reference sample was measured by IR tomography. Samples were contaminated with Cu.
以下、実施例１と同様に、図２（Ｈ）〜（Ｉ）に示すように、上記参照用サンプルをケミカルエッチング処理、μ−ＰＣＤ法によるＣｕの再結合ライフタイム測定を行った。図２（Ｊ）に示すように、参照用サンプルに関して、よこ軸に得られたＣｕの再結合ライフタイムを、たて軸に熱処理後に測定したＬＳＴＤ密度（酸素析出物密度）をプロットし、５０個以上の再結合ライフタイムの値と５０個以上の酸素析出物密度の値から相関直線を作成し、これを検量線βとした。この検量線βを図４に示す。この検量線のＲ２は０．９２７７であり、高い相関関係を示した。 Thereafter, as in Example 1, as shown in FIGS. 2H to 2I, the reference sample was subjected to chemical etching treatment and Cu recombination lifetime measurement by μ-PCD method. As shown in FIG. 2 (J), for the reference sample, the recombination lifetime of Cu obtained on the horizontal axis is plotted, and the LSTD density (oxygen precipitate density) measured after heat treatment is plotted on the vertical axis. A correlation line was created from the value of the recombination lifetime of at least one piece and the value of the density of oxygen precipitates of at least 50 pieces, and this was used as a calibration curve β. This calibration curve β is shown in FIG. R 2 of this calibration curve was 0.9277, indicating a high correlation.
図２（Ｋ）〜（Ｒ）に示すように、実施例１の検査用サンプルと同様に実施例２の検査用サンプルを準備した後、検査用サンプルの酸素析出物密度を測定することなく、実施例１の参照用サンプルと同様に検査用サンプルを処理して検査用サンプルのＣｕの再結合ライフタイムをμ−ＰＣＤ法により測定した。具体的には、参照用サンプルを準備したシリコン単結晶とは別に、ＣＺ法によりＣＯＰや転移クラスタが存在しないＰi領域及びＰv領域を含むように引上げられた棒状のシリコン単結晶からシリコンウェーハ（厚さ１ｍｍ、直径３００ｍｍ、抵抗値１０Ω・ｃｍ、酸素濃度１０×１０１７ａｔｏｍｓ／ｃｍ３（旧ＡＳＴＭ））を切り出し、このウェーハを検査用サンプルとした。この検査用サンプルに対して、参照用サンプルと同様に、熱処理、Ｃｕ汚染、第１温度までの昇温によるＣｕ拡散熱処理、第２温度での維持、室温冷却、ケミカルエッチング処理、Ｃｕの再結合ライフタイム測定を行った。 2 (K) to (R), after preparing the test sample of Example 2 in the same manner as the test sample of Example 1, without measuring the oxygen precipitate density of the test sample, The test sample was processed in the same manner as the reference sample of Example 1, and the Cu recombination lifetime of the test sample was measured by the μ-PCD method. Specifically, apart from the silicon single crystal for which the reference sample is prepared, a silicon wafer (thickness) is obtained from a rod-like silicon single crystal pulled by CZ method so as to include a Pi region and a Pv region where no COP or transition cluster exists. A thickness of 1 mm, a diameter of 300 mm, a resistance value of 10 Ω · cm, an oxygen concentration of 10 × 10 17 atoms / cm 3 (former ASTM) was cut out, and this wafer was used as an inspection sample. For this test sample, as with the reference sample, heat treatment, Cu contamination, Cu diffusion heat treatment by raising the temperature to the first temperature, maintenance at the second temperature, room temperature cooling, chemical etching treatment, Cu recombination Lifetime measurement was performed.
図２（Ｓ）に示すように、得られた再結合ライフタイムの値を図４に示す検量線βに照合して、検査用サンプルのＬＳＴＤ密度（酸素析出物密度）を推定した。この検査用サンプルについて、確認のため、赤外散乱トモグラフィ（レイテックス社製ＭＯ−４４１）でＬＳＴＤ密度を測定したところ、図４のたて軸の値とほぼ同一の値を示した。 As shown in FIG. 2 (S), the value of the obtained recombination lifetime was collated with the calibration curve β shown in FIG. 4 to estimate the LSTD density (oxygen precipitate density) of the test sample. For confirmation, the LSTD density of this test sample was measured by infrared scattering tomography (MO-441 manufactured by Raytex Co., Ltd.), and the value was almost the same as the value of the vertical axis in FIG.
＜比較例１＞
図２（Ｅ）〜（Ｇ）に示した実施例１の第１温度までの昇温によるＣｕ拡散熱処理、第２温度での維持、室温冷却を以下に記載するように変更した。即ち、参照用サンプルを１０００℃で５分間維持した後、電気炉から参照用サンプルを取り出し、放置することによって、室温まで５０℃／分の速度で急冷した。それ以外は、図２（Ａ）〜（Ｄ）に示すように、実施例１と同様にして、参照用サンプルを準備し、ＩＲトモグラフィにより参照用サンプルの酸素析出物密度を測定し、参照用サンプルをＣｕで汚染した。
<Comparative Example 1>
The Cu diffusion heat treatment by raising the temperature to the first temperature of Example 1 shown in FIGS. 2E to 2G, the maintenance at the second temperature, and the room temperature cooling were changed as described below. That is, after maintaining the reference sample at 1000 ° C. for 5 minutes, the reference sample was taken out from the electric furnace and allowed to stand, thereby rapidly cooling to room temperature at a rate of 50 ° C./min. Otherwise, as shown in FIGS. 2 (A) to (D), a reference sample was prepared in the same manner as in Example 1, and the oxygen precipitate density of the reference sample was measured by IR tomography. Samples were contaminated with Cu.
以下、実施例１と同様に、図２（Ｈ）〜（Ｉ）に示すように、上記参照用サンプルをケミカルエッチング処理、μ−ＰＣＤ法によるＣｕの再結合ライフタイム測定を行った。図２（Ｊ）に示すように、参照用サンプルに関して、よこ軸に得られたＣｕの再結合ライフタイムを、たて軸に熱処理後に測定したＬＳＴＤ密度（酸素析出物密度）をプロットし、５０個以上の再結合ライフタイムの値と５０個以上の酸素析出物密度の値から相関直線を作成し、これを検量線γとした。この検量線γを図５に示す。この検量線のＲ２は０．２５０７であり、低い相関関係を示した。 Thereafter, as in Example 1, as shown in FIGS. 2H to 2I, the reference sample was subjected to chemical etching treatment and Cu recombination lifetime measurement by μ-PCD method. As shown in FIG. 2 (J), for the reference sample, the recombination lifetime of Cu obtained on the horizontal axis is plotted, and the LSTD density (oxygen precipitate density) measured after heat treatment is plotted on the vertical axis. A correlation line was created from the value of the recombination lifetime of at least one and the value of the density of oxygen precipitates of 50 or more, and this was used as a calibration curve γ. This calibration curve γ is shown in FIG. R 2 of this calibration curve was 0.2507, indicating a low correlation.
図２（Ｋ）〜（Ｒ）に示すように、実施例１の検査用サンプルと同様に比較例１の検査用サンプルを準備した後、検査用サンプルの酸素析出物密度を測定することなく、実施例１の参照用サンプルと同様に検査用サンプルを処理して検査用サンプルのＣｕの再結合ライフタイムをμ−ＰＣＤ法により測定した。具体的には、参照用サンプルを準備したシリコン単結晶とは別に、ＣＺ法によりＣＯＰや転移クラスタが存在しないＰi領域及びＰv領域を含むように引上げられた棒状のシリコン単結晶からシリコンウェーハ（厚さ１ｍｍ、直径３００ｍｍ、抵抗値１０Ω・ｃｍ、酸素濃度１０×１０１７ａｔｏｍｓ／ｃｍ３（旧ＡＳＴＭ））を切り出し、このウェーハを検査用サンプルとした。この検査用サンプルに対して、降温を行うことなく、参照用サンプルと同様に、熱処理、Ｃｕ汚染、Ｃｕ拡散熱処理、室温冷却、ケミカルエッチング処理、μ−ＰＣＤ法によるＣｕの再結合ライフタイム測定を行った。 As shown in FIGS. 2 (K) to (R), after preparing the test sample of Comparative Example 1 in the same manner as the test sample of Example 1, without measuring the oxygen precipitate density of the test sample, The test sample was processed in the same manner as the reference sample of Example 1, and the Cu recombination lifetime of the test sample was measured by the μ-PCD method. Specifically, apart from the silicon single crystal for which the reference sample is prepared, a silicon wafer (thickness) is obtained from a rod-like silicon single crystal pulled by CZ method so as to include a Pi region and a Pv region where no COP or transition cluster exists. A thickness of 1 mm, a diameter of 300 mm, a resistance value of 10 Ω · cm, an oxygen concentration of 10 × 10 17 atoms / cm 3 (former ASTM) was cut out, and this wafer was used as an inspection sample. For this sample for inspection, heat treatment, Cu contamination, Cu diffusion heat treatment, room temperature cooling, chemical etching treatment, and Cu recombination lifetime measurement by μ-PCD method are performed in the same manner as the reference sample without lowering the temperature. went.
図２（Ｓ）に示すように、得られた再結合ライフタイムの値を図５に示す検量線γに照合して、検査用サンプルのＬＳＴＤ密度（酸素析出物密度）を推定した。この検査用サンプルについて、確認のため、赤外散乱トモグラフィ（レイテックス社製ＭＯ−４４１）でＬＳＴＤ密度を測定したところ、図５のたて軸の値と大きく異なる値を示した。 As shown in FIG. 2 (S), the obtained recombination lifetime value was collated with the calibration curve γ shown in FIG. 5 to estimate the LSTD density (oxygen precipitate density) of the test sample. For confirmation, the LSTD density of this test sample was measured by infrared scattering tomography (MO-441 manufactured by Raytex Co., Ltd.) and showed a value greatly different from the value of the vertical axis in FIG.
＜比較例２＞
図２（Ｅ）〜（Ｇ）に示した実施例１の第１温度までの昇温によるＣｕ拡散熱処理、第２温度での維持、室温冷却を以下に記載するように変更した。即ち、参照用サンプルを７００℃で５分間維持した後、電気炉から参照用サンプルを取り出し、放置することによって、室温まで５０℃／分の速度で急冷した。それ以外は、図２（Ａ）〜（Ｄ）に示すように、実施例１と同様にして、参照用サンプルを準備し、ＩＲトモグラフィにより参照用サンプルの酸素析出物密度を測定し、参照用サンプルをＣｕで汚染した。
<Comparative Example 2>
The Cu diffusion heat treatment by raising the temperature to the first temperature of Example 1 shown in FIGS. 2E to 2G, the maintenance at the second temperature, and the room temperature cooling were changed as described below. That is, after maintaining the reference sample at 700 ° C. for 5 minutes, the reference sample was taken out from the electric furnace and allowed to stand to be rapidly cooled to room temperature at a rate of 50 ° C./min. Otherwise, as shown in FIGS. 2 (A) to (D), a reference sample was prepared in the same manner as in Example 1, and the oxygen precipitate density of the reference sample was measured by IR tomography. Samples were contaminated with Cu.
以下、実施例１と同様に、図２（Ｈ）〜（Ｉ）に示すように、上記参照用サンプルをケミカルエッチング処理、μ−ＰＣＤ法によるＣｕの再結合ライフタイム測定を行った。図２（Ｊ）に示すように、参照用サンプルに関して、よこ軸に得られたＣｕの再結合ライフタイムを、たて軸に熱処理後に測定したＬＳＴＤ密度（酸素析出物密度）をプロットし、５０個以上の再結合ライフタイムの値と５０個以上の酸素析出物密度の値から相関直線を作成し、これを検量線δとした。この検量線δを図６に示す。この検量線のＲ２は０．３０６１であり、低い相関関係を示した。 Thereafter, as in Example 1, as shown in FIGS. 2H to 2I, the reference sample was subjected to chemical etching treatment and Cu recombination lifetime measurement by μ-PCD method. As shown in FIG. 2 (J), for the reference sample, the recombination lifetime of Cu obtained on the horizontal axis is plotted, and the LSTD density (oxygen precipitate density) measured after heat treatment is plotted on the vertical axis. A correlation line was created from the value of the recombination lifetime of at least one piece and the value of the density of oxygen precipitates of at least 50 pieces, and this was used as a calibration curve δ. This calibration curve δ is shown in FIG. R 2 of this calibration curve was 0.3061, indicating a low correlation.
図２（Ｋ）〜（Ｒ）に示すように、実施例１の検査用サンプルと同様に比較例１の検査用サンプルを準備した後、検査用サンプルの酸素析出物密度を測定することなく、実施例１の参照用サンプルと同様に検査用サンプルを処理して検査用サンプルのＣｕの再結合ライフタイムをμ−ＰＣＤ法により測定した。具体的には、参照用サンプルを準備したシリコン単結晶とは別に、ＣＺ法によりＣＯＰや転移クラスタが存在しないＰi領域及びＰv領域を含むように引上げられた棒状のシリコン単結晶からシリコンウェーハ（厚さ１ｍｍ、直径３００ｍｍ、抵抗値１０Ω・ｃｍ、酸素濃度１０×１０１７ａｔｏｍｓ／ｃｍ３（旧ＡＳＴＭ））を切り出し、このウェーハを検査用サンプルとした。この検査用サンプルに対して、降温を行うことなく、参照用サンプルと同様に、熱処理、Ｃｕ汚染、Ｃｕ拡散熱処理、室温冷却、ケミカルエッチング処理、μ−ＰＣＤ法によるＣｕの再結合ライフタイム測定を行った。 As shown in FIGS. 2 (K) to (R), after preparing the test sample of Comparative Example 1 in the same manner as the test sample of Example 1, without measuring the oxygen precipitate density of the test sample, The test sample was processed in the same manner as the reference sample of Example 1, and the Cu recombination lifetime of the test sample was measured by the μ-PCD method. Specifically, apart from the silicon single crystal for which the reference sample is prepared, a silicon wafer (thickness) is obtained from a rod-like silicon single crystal pulled by CZ method so as to include a Pi region and a Pv region where no COP or transition cluster exists. A thickness of 1 mm, a diameter of 300 mm, a resistance value of 10 Ω · cm, an oxygen concentration of 10 × 10 17 atoms / cm 3 (former ASTM) was cut out, and this wafer was used as an inspection sample. For this sample for inspection, heat treatment, Cu contamination, Cu diffusion heat treatment, room temperature cooling, chemical etching treatment, and Cu recombination lifetime measurement by μ-PCD method are performed in the same manner as the reference sample without lowering the temperature. went.
図２（Ｓ）に示すように、得られた再結合ライフタイムの値を図６に示す検量線δに照合して、検査用サンプルのＬＳＴＤ密度（酸素析出物密度）を推定した。この検査用サンプルについて、確認のため、赤外散乱トモグラフィ（レイテックス社製ＭＯ−４４１）でＬＳＴＤ密度を測定したところ、図６のたて軸の値と大きく異なる値を示した。 As shown in FIG. 2 (S), the value of the obtained recombination lifetime was collated with the calibration curve δ shown in FIG. 6 to estimate the LSTD density (oxygen precipitate density) of the test sample. The LSTD density of this test sample was measured by infrared scattering tomography (MO-441 manufactured by Raytex Co., Ltd.) for confirmation, and showed a value greatly different from the value of the vertical axis in FIG.
本発明の検査方法を用いれば、検査結果に基づいて、ＣＺ法によるシリコン単結晶の引上げ条件を決定し、この決定された引上げ条件で単結晶内の酸素析出物密度を制御してシリコン単結晶を育成することができる。また検査結果に基づいて、検査用サンプルを準備したシリコン単結晶から切り出されたシリコンウェーハの品質を判定することができる。 If the inspection method of the present invention is used, the pulling condition of the silicon single crystal by the CZ method is determined based on the inspection result, and the oxygen precipitate density in the single crystal is controlled by the determined pulling condition to thereby determine the silicon single crystal. Can be nurtured. Further, based on the inspection result, the quality of the silicon wafer cut out from the silicon single crystal for which the inspection sample is prepared can be determined.
Claims (10)
(ii) サンプル内の酸素析出核を酸素析出物に成長させるために前記サンプルを熱処理する工程と、
(iii) 前記熱処理したサンプル表面をＣｕで汚染する工程と、
(iv) 前記Ｃｕで汚染したサンプルをサンプル内にＣｕシリサイドが生成しない３００℃を超える第１温度まで昇温して前記Ｃｕをサンプル内に熱拡散させる工程と、
(v) 前記Ｃｕをサンプル内に熱拡散させたサンプルを前記第１温度と同じか異なる３００℃を超える第２温度で維持して前記サンプル内の酸素起因の結晶欠陥にＣｕを析出させるとともに前記結晶欠陥に析出させた以外の余剰のＣｕをサンプル表面に拡散させる工程と、
(vi) 前記第２温度で維持したサンプルを室温まで冷却する工程と、
(vii) 前記室温まで冷却したサンプル表面を洗浄した後、ケミカルエッチング処理する工程と、
(viii) 前記ケミカルエッチング処理したサンプルの前記Ｃｕの再結合ライフタイムを測定する工程と
を含むシリコンウェーハの検査方法。 (i) preparing a sample of a wafer cut from a rod-like silicon single crystal grown by the Czochralski method;
(ii) heat treating the sample to grow oxygen precipitate nuclei in the sample into oxygen precipitates;
(iii) contaminating the heat-treated sample surface with Cu;
(iv) heating the sample contaminated with Cu to a first temperature exceeding 300 ° C. at which Cu silicide is not generated in the sample and thermally diffusing the Cu into the sample;
(v) maintaining a sample obtained by thermally diffusing the Cu in the sample at a second temperature exceeding 300 ° C. which is the same as or different from the first temperature, and depositing Cu on crystal defects caused by oxygen in the sample; A step of diffusing excess Cu other than precipitated in crystal defects on the sample surface;
(vi) cooling the sample maintained at the second temperature to room temperature;
(vii) cleaning the sample surface cooled to room temperature, and then performing a chemical etching process;
(viii) a step of measuring the Cu recombination lifetime of the chemically etched sample, and a silicon wafer inspection method.
(B) サンプル内の酸素析出核を酸素析出物に成長させるために前記複数の参照用サンプルを熱処理する工程と、
(C) 前記熱処理した複数の参照用サンプルについて赤外散乱トモグラフィにより酸素析出物密度を測定する工程と、
(D) 前記熱処理した複数の参照用サンプル表面をＣｕで汚染する工程と、
(E) 前記Ｃｕで汚染した複数の参照用サンプルをサンプル内にＣｕシリサイドが生成しない３００℃を超える第１温度まで昇温して前記Ｃｕをサンプル内に熱拡散させる工程と、
(F) 前記Ｃｕをサンプル内に熱拡散させた複数の参照用サンプルを前記第１温度と同じか異なる３００℃を超える第２温度で維持して前記サンプル内の酸素起因の結晶欠陥にＣｕを析出させるとともに前記結晶欠陥に析出させた以外の余剰のＣｕをサンプル表面に拡散させる工程と、
(G) 前記第２温度で維持した参照用サンプルを室温まで冷却する工程と、
(H) 前記室温まで冷却した複数の参照用サンプル表面を洗浄した後、ケミカルエッチング処理する工程と、
(I) 前記ケミカルエッチング処理した複数の参照用サンプルの前記Ｃｕの再結合ライフタイムを測定する工程と、
(J) 前記(I)工程の測定結果と前記(C)工程の測定結果から、再結合ライフタイムと酸素析出物密度との相関直線からなる検量線を作成する工程と、
(K) チョクラルスキー法により育成された棒状のシリコン単結晶から切り出されたウェーハから検査用サンプルを準備する工程と、
(L) 前記検査用サンプルを前記(B)工程と同じ条件で熱処理する工程と、
(M) 前記熱処理した検査用サンプル表面を前記(D)工程と同じ条件でＣｕで汚染する工程と、
(N) 前記Ｃｕで汚染した検査用サンプルを前記(E)工程と同じ条件で前記Ｃｕをサンプル内に熱拡散させる工程と、
(O) 前記Ｃｕをサンプル内に熱拡散させた複数の検査用サンプルを前記(F)工程と同じ第２温度で維持して前記サンプル内の酸素起因の結晶欠陥にＣｕを析出させるとともに前記結晶欠陥に析出させた以外の余剰のＣｕをサンプル表面に拡散させる工程と、
(P) 前記第２温度で維持した検査用サンプルを室温まで冷却する工程と、
(Q) 前記室温まで冷却した検査用サンプル表面を洗浄した後、ケミカルエッチング処理する工程と、
(R) 前記ケミカルエッチング処理した検査用サンプルの前記Ｃｕの再結合ライフタイムを測定する工程と、
(S) 前記(R)工程の測定結果を前記(J)工程で作成した検量線に照合することにより、前記検査用サンプルの酸素析出物密度を推定する工程と
を含むシリコンウェーハの検査方法。 (A) preparing a plurality of reference samples from a wafer cut from a rod-shaped silicon single crystal grown by the Czochralski method;
(B) heat treating the plurality of reference samples to grow oxygen precipitate nuclei in the sample into oxygen precipitates;
(C) measuring the oxygen precipitate density by infrared scattering tomography for the plurality of heat-treated reference samples;
(D) contaminating the surface of the plurality of heat-treated reference samples with Cu;
(E) heating a plurality of reference samples contaminated with Cu to a first temperature exceeding 300 ° C. at which Cu silicide is not generated in the sample and thermally diffusing the Cu into the sample;
(F) Maintaining a plurality of reference samples obtained by thermally diffusing the Cu in the sample at a second temperature exceeding 300 ° C. which is the same as or different from the first temperature, and adding Cu to the oxygen-induced crystal defects in the sample. A step of diffusing excess Cu other than being precipitated and deposited on the crystal defects to the sample surface;
(G) cooling the reference sample maintained at the second temperature to room temperature;
(H) cleaning a plurality of reference sample surfaces cooled to the room temperature, and then performing a chemical etching process;
(I) measuring the Cu recombination lifetime of the plurality of reference samples subjected to chemical etching; and
(J) From the measurement result of the step (I) and the measurement result of the step (C), a step of creating a calibration curve consisting of a correlation line between the recombination lifetime and the oxygen precipitate density;
(K) preparing a test sample from a wafer cut from a rod-shaped silicon single crystal grown by the Czochralski method;
(L) the step of heat-treating the inspection sample under the same conditions as the step (B),
(M) a step of contaminating the heat-treated test sample surface with Cu under the same conditions as in the step (D);
(N) a step of thermally diffusing the Cu in the sample under the same conditions as the step (E) for the sample for inspection contaminated with the Cu;
(O) A plurality of inspection samples in which the Cu is thermally diffused in the sample are maintained at the same second temperature as in the step (F) to precipitate Cu on crystal defects caused by oxygen in the sample and the crystal A step of diffusing excess Cu other than the precipitated Cu on the sample surface;
(P) cooling the inspection sample maintained at the second temperature to room temperature;
(Q) cleaning the sample surface for inspection cooled to the room temperature, and then performing a chemical etching process;
(R) measuring the Cu recombination lifetime of the chemical-etched test sample;
(S) A method for inspecting a silicon wafer, comprising: comparing the measurement result of the step (R) with the calibration curve created in the step (J) to estimate the oxygen precipitate density of the inspection sample.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2015209676A JP6459900B2 (en) | 2015-10-26 | 2015-10-26 | Inspection method of silicon wafer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2015209676A JP6459900B2 (en) | 2015-10-26 | 2015-10-26 | Inspection method of silicon wafer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2017084895A JP2017084895A (en) | 2017-05-18 |
| JP6459900B2 true JP6459900B2 (en) | 2019-01-30 |
Family
ID=58713212
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2015209676A Active JP6459900B2 (en) | 2015-10-26 | 2015-10-26 | Inspection method of silicon wafer |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP6459900B2 (en) |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01242498A (en) * | 1988-03-25 | 1989-09-27 | Shin Etsu Handotai Co Ltd | Heat treatment of gallium arsenide single crystal |
| JP2001081000A (en) * | 1999-09-08 | 2001-03-27 | Shin Etsu Handotai Co Ltd | Method of evaluating crystal defect in silicon single crystal |
| JP3778412B2 (en) * | 1999-10-15 | 2006-05-24 | 信越半導体株式会社 | Inspection wafer, method for producing the same, and inspection method using the same |
| JP2001213694A (en) * | 2000-01-27 | 2001-08-07 | Mitsubishi Materials Silicon Corp | Semiconductor wafer with low copper content |
| JP2001338959A (en) * | 2000-05-30 | 2001-12-07 | Toshiba Corp | Method and equipment for evaluating semiconductor substrate |
| JP3896919B2 (en) * | 2002-07-29 | 2007-03-22 | 信越半導体株式会社 | Method for evaluating Ni contamination of silicon wafer |
| DE102007044924A1 (en) * | 2006-09-25 | 2008-06-12 | Siltron Inc., Gumi | A method of identifying crystal defect areas in monocrystalline silicon using metal doping and heat treatment |
| JP5621612B2 (en) * | 2011-01-19 | 2014-11-12 | 株式会社Sumco | Silicon single crystal inspection method and manufacturing method |
-
2015
- 2015-10-26 JP JP2015209676A patent/JP6459900B2/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| JP2017084895A (en) | 2017-05-18 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7632349B2 (en) | Silicon wafer surface defect evaluation method | |
| TWI539041B (en) | Semiconductor wafer composed of monocrystalline silicon and method for producing it | |
| JP5519305B2 (en) | Method for detecting defects in silicon carbide single crystal | |
| US7901132B2 (en) | Method of identifying crystal defect region in monocrystalline silicon using metal contamination and heat treatment | |
| CN102768134B (en) | Method for displaying and detecting void type defects in Czochralski silicon wafer | |
| JP5621612B2 (en) | Silicon single crystal inspection method and manufacturing method | |
| KR100763834B1 (en) | Method of identifying crystal defect region in crystalline silicon using copper haze and copper solution for identifying crystal defect region | |
| TW201339378A (en) | Qualitative crystal defect evaluation method | |
| CN112986294A (en) | Wafer defect detection method and device | |
| JP5381558B2 (en) | Pulling method of silicon single crystal | |
| TWI717628B (en) | Metal pollution evaluation method | |
| US7074271B2 (en) | Method of identifying defect distribution in silicon single crystal ingot | |
| JP6459900B2 (en) | Inspection method of silicon wafer | |
| JP6418085B2 (en) | Silicon single crystal inspection method and manufacturing method | |
| JP4284886B2 (en) | Method for evaluating oxygen precipitate density in silicon wafers | |
| JP6870587B2 (en) | Evaluation method of silicon single crystal and manufacturing method of silicon wafer | |
| JP5742742B2 (en) | Metal contamination assessment method | |
| JP3933010B2 (en) | Method for measuring point defect distribution of silicon single crystal ingot | |
| JP5928363B2 (en) | Evaluation method of silicon single crystal wafer | |
| JP4675542B2 (en) | Evaluation method of gettering ability | |
| CN105900220B (en) | The heat treatment method of monocrystalline silicon wafer crystal | |
| JP5949303B2 (en) | Epitaxial growth furnace evaluation method and epitaxial wafer manufacturing method | |
| JP3915606B2 (en) | Method for measuring point defect distribution of silicon single crystal ingot | |
| JP3874255B2 (en) | Evaluation method of BMD size in silicon wafer | |
| JP2019149416A (en) | Epitaxial silicon wafer manufacturing method and epitaxial silicon wafer |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20171207 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20181005 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20181016 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20181109 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20181204 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20181217 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 6459900 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |