JP2023038054A - Cleaning method and manufacturing method of silicon wafer, and evaluation method and management method of hydrogen peroxide concentration in cleaning solution - Google Patents
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- 238000004140 cleaning Methods 0.000 title claims abstract description 298
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 title claims abstract description 171
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 107
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 107
- 239000010703 silicon Substances 0.000 title claims abstract description 107
- 238000000034 method Methods 0.000 title claims abstract description 93
- 238000011156 evaluation Methods 0.000 title claims abstract description 22
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 16
- 238000007726 management method Methods 0.000 title abstract description 3
- 238000007788 roughening Methods 0.000 claims abstract description 119
- 239000000243 solution Substances 0.000 claims abstract description 61
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims abstract description 36
- 239000000908 ammonium hydroxide Substances 0.000 claims abstract description 30
- 239000007864 aqueous solution Substances 0.000 claims abstract description 16
- 239000007788 liquid Substances 0.000 claims description 89
- 238000005406 washing Methods 0.000 claims description 48
- 238000011835 investigation Methods 0.000 claims description 46
- 238000012545 processing Methods 0.000 claims description 13
- 239000002245 particle Substances 0.000 claims description 12
- 235000011114 ammonium hydroxide Nutrition 0.000 abstract description 29
- 235000012431 wafers Nutrition 0.000 description 139
- 238000005530 etching Methods 0.000 description 17
- 239000000126 substance Substances 0.000 description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 12
- 230000008569 process Effects 0.000 description 11
- 238000007254 oxidation reaction Methods 0.000 description 10
- 239000000203 mixture Substances 0.000 description 8
- 230000003647 oxidation Effects 0.000 description 8
- 229910004298 SiO 2 Inorganic materials 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 230000005660 hydrophilic surface Effects 0.000 description 5
- 238000005498 polishing Methods 0.000 description 5
- 239000005871 repellent Substances 0.000 description 5
- 230000003746 surface roughness Effects 0.000 description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 4
- 238000002835 absorbance Methods 0.000 description 4
- 229910052739 hydrogen Inorganic materials 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 238000004630 atomic force microscopy Methods 0.000 description 2
- 230000008859 change Effects 0.000 description 2
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- 238000002156 mixing Methods 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 238000000137 annealing Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
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- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000007429 general method Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- QOSATHPSBFQAML-UHFFFAOYSA-N hydrogen peroxide;hydrate Chemical compound O.OO QOSATHPSBFQAML-UHFFFAOYSA-N 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
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- 239000005416 organic matter Substances 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 150000002978 peroxides Chemical class 0.000 description 1
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- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02041—Cleaning
- H01L21/02043—Cleaning before device manufacture, i.e. Begin-Of-Line process
- H01L21/02052—Wet cleaning only
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
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- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
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- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
- H01L21/304—Mechanical treatment, e.g. grinding, polishing, cutting
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- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
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- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
- H01L21/67005—Apparatus not specifically provided for elsewhere
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Abstract
Description
本発明は、シリコンウェーハの表裏面又は裏面を粗化することができるシリコンウェーハの洗浄方法および製造方法、並びに洗浄液中の過酸化水素濃度評価方法および過酸化水素濃度管理方法に関する。 The present invention relates to a silicon wafer cleaning method and manufacturing method capable of roughening the front and back surfaces or the back surface of a silicon wafer, a hydrogen peroxide concentration evaluation method in a cleaning liquid, and a hydrogen peroxide concentration control method.
半導体デバイス用のシリコンウェーハの製造工程は、チョクラルスキー（ＣＺ）法等を使用して単結晶インゴットを育成する単結晶製造工程と、この単結晶インゴットをスライスし、鏡面状に加工するウェーハ加工工程とから構成され、さらに付加価値をつけるために、熱処理をするアニール工程やエピタキシャル層を形成するエピタキシャル成長工程を含む場合がある。 The manufacturing process of silicon wafers for semiconductor devices consists of a single crystal manufacturing process in which a single crystal ingot is grown using the Czochralski (CZ) method, etc., and a wafer processing process in which the single crystal ingot is sliced and processed into a mirror surface. In order to further add value, it may include an annealing step for heat treatment and an epitaxial growth step for forming an epitaxial layer.
この鏡面状に加工する工程には、ＤＳＰ（両面研磨）工程とその後のＣＭＰ（片面研磨）工程がある。より具体的には、パーティクル品質や搬送の観点からＤＳＰ加工されたウェーハは乾燥させず、必要に応じて洗浄した後、水中保管でＣＭＰ工程へ搬送される。したがってＣＭＰ工程では水中保管されたウェーハをロボット等でチャックしＣＭＰ装置へ搬送する必要がある。また、ＣＭＰ加工後も同様に研磨剤や純水などで濡れたウェーハをチャックし、必要に応じて洗浄工程へ搬送する必要がある。 The process of mirror-finishing includes a DSP (double-sided polishing) process and a subsequent CMP (single-sided polishing) process. More specifically, from the viewpoint of particle quality and transportation, the DSP-processed wafers are not dried, but are washed as necessary and then stored in water and transported to the CMP process. Therefore, in the CMP process, it is necessary to chuck the wafer stored in water by a robot or the like and transport it to the CMP apparatus. Also, after the CMP process, similarly, it is necessary to chuck the wafer wet with an abrasive or pure water and transport it to a cleaning process as necessary.
このようにウェーハの加工工程では、ドライではなくウェットな環境下でウェーハを搬送することが必須であるが、特にこのようなウェット環境下では、チャックで吸着されたウェーハを脱離させる際に、チャックを解除しても脱離されず、搬送不良を引き起こすことがあった。この原因としてはチャックされるウェーハ面の粗さが影響していると考えられ、チャックされるウェーハ面粗さが良好過ぎると、チャックとの接触面積が増え、チャックを解除してもウェーハが脱離しにくくなると考えられ、対してウェーハの面粗さが悪いと接触面積が減り、ウェーハが脱離しやすくなると考えられる。一般的にチャックされた面は少なからずチャック痕が形成されやすく、品質が低下することからチャック面はシリコンウェーハの裏面であることが多い。したがって、搬送不良低減の観点からは特にシリコンウェーハ裏面のみ粗い方が良く、そのようなウェーハの製造方法が求められている。 In this way, in the wafer processing process, it is essential to transport the wafer in a wet environment rather than a dry environment. Even if the chuck is released, the wafer is not detached, causing a transport failure. The reason for this is considered to be the roughness of the chucked wafer surface. On the other hand, if the surface roughness of the wafer is poor, the contact area is reduced and the wafer is likely to be detached. In general, the chucked surface is likely to form chuck marks in no small amount, degrading the quality, so the chucked surface is often the back surface of the silicon wafer. Therefore, from the viewpoint of reducing transportation defects, it is preferable that only the back surface of the silicon wafer is rough, and a method for manufacturing such a wafer is desired.
一般的なシリコンウェーハの洗浄方法として、ＲＣＡ洗浄と呼ばれる方法がある。このＲＣＡ洗浄とはＳＣ１（Ｓｔａｎｄａｒｄ Ｃｌｅａｎｉｎｇ １）洗浄、ＳＣ２（Ｓｔａｎｄａｒｄ Ｃｌｅａｎｉｎｇ ２）洗浄、ＤＨＦ（Ｄｉｌｕｔｅｄ Ｈｙｄｒｏｆｌｕｏｒｉｃ Ａｃｉｄ）洗浄を、目的に応じて組み合わせて行う洗浄方法である。
このＳＣ１洗浄とは、アンモニア水と過酸化水素水を任意の割合で混合し、アルカリ性の洗浄液によるシリコンウェーハ表面のエッチングによって付着パーティクルをリフトオフさせ、さらにシリコンウェーハとパーティクルの静電気的な反発を利用して、シリコンウェーハへの再付着を抑えながらパーティクルを除去する洗浄方法である。また、ＳＣ２洗浄とは、塩酸と過酸化水素水を任意の割合で混合した洗浄液で、シリコンウェーハ表面の金属不純物を溶解除去する洗浄方法である。また、ＤＨＦ洗浄とは、希フッ酸によってシリコンウェーハ表面のケミカル酸化膜を除去する洗浄方法である。さらに、強い酸化力を有するオゾン水洗浄も使用される場合があり、シリコンウェーハ表面に付着している有機物の除去やＤＨＦ洗浄後のシリコンウェーハ表面のケミカル酸化膜形成を行っている。シリコンウェーハの洗浄は、目的に応じてこれらの洗浄を組み合わせて行われている。
この中でＳＣ１洗浄はエッチングを伴う洗浄であるため、ＳＣ１洗浄後はウェーハの面粗さが増加することが一般的に知られている。
As a general silicon wafer cleaning method, there is a method called RCA cleaning. The RCA cleaning is a cleaning method in which SC1 (Standard Cleaning 1) cleaning, SC2 (Standard Cleaning 2) cleaning, and DHF (Diluted Hydrofluoric Acid) cleaning are combined according to the purpose.
This SC1 cleaning involves mixing ammonia water and hydrogen peroxide water in an arbitrary ratio, etching the surface of the silicon wafer with an alkaline cleaning liquid to lift off adhering particles, and further utilizing electrostatic repulsion between the silicon wafer and the particles. It is a cleaning method that removes particles while suppressing redeposition to silicon wafers. SC2 cleaning is a cleaning method for dissolving and removing metal impurities on the surface of a silicon wafer with a cleaning liquid in which hydrochloric acid and hydrogen peroxide are mixed at an arbitrary ratio. DHF cleaning is a cleaning method for removing a chemical oxide film on the surface of a silicon wafer with dilute hydrofluoric acid. Furthermore, ozone water cleaning with strong oxidizing power is sometimes used to remove organic matter adhering to the silicon wafer surface and to form a chemical oxide film on the silicon wafer surface after DHF cleaning. Cleaning of silicon wafers is performed in combination with these cleaning methods depending on the purpose.
Among them, SC1 cleaning involves etching, so it is generally known that the surface roughness of the wafer increases after SC1 cleaning.
また、ウェーハの面粗さを評価する手法としては、ＡＦＭ（原子間力顕微鏡：Ａｔｏｍｉｃ Ｆｏｒｃｅ Ｍｉｃｒｏｓｃｏｐｙ）により得られるＳａ（３次元算出平均高さ）値やパーティクルカウンターにより得られるＨａｚｅ値を指標とすることができる。Ｈａｚｅとはいわゆる曇りとして表現されるものであり、シリコン表面の粗さの指標として広く用いられており、このＨａｚｅレベルが高いとはウェーハの面が粗いことを示す。パーティクルカウンターによるＨａｚｅ検査はスループットが非常に高く、ウェーハ全面を検査することができる。 In addition, as a method for evaluating the surface roughness of a wafer, the Sa (three-dimensional calculated average height) value obtained by AFM (Atomic Force Microscopy) and the Haze value obtained by a particle counter are used as indices. be able to. Haze is expressed as so-called cloudiness and is widely used as an index of silicon surface roughness, and a high haze level indicates that the wafer surface is rough. Haze inspection using a particle counter has a very high throughput and can inspect the entire wafer surface.
特許文献１には水酸化アンモニウムと過酸化水素と水の組成が１：１：５～１：１：２０００の範囲の希釈水溶液でシリコンウェーハを洗浄し、異なる厚さの自然酸化膜を形成させる方法が記載されている。
特許文献２にはＳＣ１洗浄において、水酸化アンモニウムから電離されたＯＨ－の濃度が高いとＳｉの直接エッチングが優先的に起こり、ウェーハ表面粗さが増加することが記載されている。
また、特許文献３～６にも、シリコンウェーハなどの半導体基板の洗浄に関する技術が開示されている。
In
また、ＳＣ１洗浄液は特に高温下で用いられる場合には分解や蒸発反応により水酸化アンモニウムや過酸化水素濃度が低下する。そのため薬液濃度をモニターし、濃度が一定になるように調整することが望ましい。ＳＣ１洗浄液の濃度を評価する方法としては吸光度や屈折率による濃度測定方法があり、その精度も高いことが知られているが、その濃度範囲は限られる。特に低濃度の薬液の場合は現状評価することが困難である。 Further, when the SC1 cleaning liquid is used at high temperature, the concentration of ammonium hydroxide and hydrogen peroxide decreases due to decomposition and evaporation reaction. Therefore, it is desirable to monitor the concentration of the chemical solution and adjust it so that the concentration becomes constant. As a method for evaluating the concentration of the SC1 cleaning liquid, there is a concentration measurement method based on absorbance or refractive index, which is known to have high accuracy, but its concentration range is limited. Especially in the case of low-concentration chemicals, it is difficult to evaluate at present.
前述したように、加工工程中の搬送不良低減のためにチャックされる裏面が粗いシリコンウェーハが必要とされている。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、シリコンウェーハの表裏面又は裏面を粗化できる洗浄方法、片側の面のみが選択的に粗化されたシリコンウェーハを得ることができるシリコンウェーハの製造方法、及び粗化挙動に影響を与える洗浄液中の微量の過酸化水素濃度の評価方法、管理方法を提供することにある。 As mentioned above, there is a need for a chucked silicon wafer with a rough backside to reduce transport failures during processing. The present invention has been made to solve the above problems, and provides a cleaning method capable of roughening the front and rear surfaces or the rear surface of a silicon wafer, and a silicon wafer having only one surface selectively roughened. An object of the present invention is to provide a method for manufacturing a silicon wafer, and a method for evaluating and controlling a minute amount of hydrogen peroxide concentration in a cleaning liquid that affects roughening behavior.
上記目的を達成するために、本発明は、シリコンウェーハを粗化する洗浄方法であって、
自然酸化膜がないベア面が露出した調査用シリコンウェーハを、水酸化アンモニウムを含み、かつ、過酸化水素濃度が０～０．１５ｗｔ％の水溶液である洗浄液で洗浄することで粗化された前記調査用シリコンウェーハの表裏面又は裏面の粗化量と、
前記洗浄液の温度と、
前記洗浄液中の水酸化アンモニウム濃度と、
前記洗浄液中の過酸化水素濃度との相関関係を予め取得しておく洗浄液濃度調査工程と、
該洗浄液濃度調査工程で取得しておいた前記相関関係に基づいて、所望の粗化量から、前記洗浄液の温度、前記洗浄液中の水酸化アンモニウム濃度及び過酸化水素濃度の粗化洗浄条件を決定する粗化洗浄条件決定工程と、
該粗化洗浄条件決定工程で決定した粗化洗浄条件で、自然酸化膜がないベア面が露出した粗化対象シリコンウェーハを洗浄することで、該粗化対象シリコンウェーハの表裏面又は裏面を粗化する粗化洗浄工程とを有することを特徴とするシリコンウェーハの洗浄方法を提供する。
To achieve the above object, the present invention provides a cleaning method for roughening a silicon wafer, comprising:
The silicon wafer for investigation, in which the bare surface without a natural oxide film is exposed, is roughened by washing with a cleaning liquid that is an aqueous solution containing ammonium hydroxide and having a hydrogen peroxide concentration of 0 to 0.15 wt%. The amount of roughening on the front and back surfaces or the back surface of the silicon wafer for investigation,
the temperature of the cleaning liquid;
ammonium hydroxide concentration in the cleaning solution;
a cleaning solution concentration investigation step of obtaining in advance a correlation with the concentration of hydrogen peroxide in the cleaning solution;
Based on the correlation obtained in the cleaning liquid concentration investigation step, roughening cleaning conditions such as the temperature of the cleaning liquid, the ammonium hydroxide concentration, and the hydrogen peroxide concentration in the cleaning liquid are determined from the desired amount of roughening. a roughening cleaning condition determining step;
The front and rear surfaces or the rear surface of the silicon wafer to be roughened is roughened by washing the silicon wafer to be roughened, the bare surface of which is free of the natural oxide film, exposed under the roughening washing condition determined in the roughening washing condition determining step. A method for cleaning a silicon wafer, characterized by comprising a roughening cleaning step.
このようなシリコンウェーハの洗浄方法であれば、表裏面又は裏面が所望の粗化量で粗化されたウェーハの製造が可能となる。さらに、粗化量に対する過酸化水素濃度依存性を調査することで、より好適な粗化洗浄条件を選定出来る。特には、粗化量のバラツキが小さくなるように粗化洗浄条件を選定して洗浄することができる。 With such a method for cleaning a silicon wafer, it is possible to manufacture a wafer in which the front and back surfaces or the back surface is roughened by a desired roughening amount. Furthermore, by examining the hydrogen peroxide concentration dependence of the roughening amount, more suitable roughening cleaning conditions can be selected. In particular, washing can be performed by selecting roughening washing conditions so as to reduce variations in the amount of roughening.
このとき、前記洗浄液濃度調査工程において、
前記調査用シリコンウェーハの前記洗浄前後にパーティクルカウンターにてＨａｚｅ値を取得し、前記洗浄後のＨａｚｅ値の増加量を前記粗化量とすることができる。
At this time, in the cleaning liquid concentration investigation step,
A haze value can be obtained with a particle counter before and after the cleaning of the silicon wafer for investigation, and an increase in the haze value after the cleaning can be used as the roughening amount.
このような方法であれば、簡便かつスループット良く粗化挙動、粗化量をモニターできる。 With such a method, the roughening behavior and the amount of roughening can be monitored simply and with high throughput.
また、前記粗化洗浄条件決定工程において前記粗化洗浄条件を決定するとき、
前記過酸化水素濃度が、該過酸化水素濃度の変動に対する前記粗化量の変動が所定値以下の濃度範囲内であり、かつ、前記粗化洗浄工程における前記洗浄後の粗化対象シリコンウェーハ表面に、該洗浄中に形成された自然酸化膜が残るように、
前記粗化洗浄条件を決定することができる。
Further, when determining the roughening cleaning conditions in the roughening cleaning condition determination step,
The hydrogen peroxide concentration is within a concentration range in which the variation in the amount of roughening with respect to the variation in the hydrogen peroxide concentration is a predetermined value or less, and the surface of the silicon wafer to be roughened after the cleaning in the roughening cleaning step. In addition, so that the native oxide film formed during the cleaning remains,
The roughening cleaning conditions can be determined.
このような方法であれば、洗浄液中の過酸化水素濃度が変化したとしても所望の粗化量で粗化されたウェーハを一層安定的に供給することができる。また、粗化度合いが一層十分なウェーハを得ることができる。 With such a method, even if the concentration of hydrogen peroxide in the cleaning liquid changes, it is possible to more stably supply wafers roughened to a desired roughening amount. Also, a wafer with a more sufficient degree of roughening can be obtained.
また、前記粗化洗浄条件決定工程において、前記洗浄液の温度を８０℃以上とすることができる。 Further, in the roughening cleaning condition determining step, the temperature of the cleaning liquid can be set to 80° C. or higher.
このような方法であれば、過酸化水度濃度の変動に対する粗化量の変動をより小さくでき、粗化されたウェーハをより一層安定的に供給することができる。 With such a method, fluctuations in the amount of roughening with respect to fluctuations in the concentration of water peroxide can be reduced, and roughened wafers can be supplied more stably.
また、本発明は、本発明のシリコンウェーハの洗浄方法により洗浄され、表裏面が粗化されたシリコンウェーハの片方の面に対し、ＣＭＰ加工を行い、前記片方の面とは反対側の面のみが選択的に粗化されているシリコンウェーハを得ることを特徴とするシリコンウェーハの製造方法を提供する。 Further, according to the present invention, one surface of a silicon wafer which has been cleaned by the method for cleaning a silicon wafer of the present invention and whose front and back surfaces have been roughened is subjected to CMP processing, and only the surface opposite to the one surface is subjected to CMP processing. Provided is a method for producing a silicon wafer characterized by obtaining a silicon wafer in which is selectively roughened.
このように、表裏面を粗化した後、片方の面のみ研磨することで、片方の面は良好な面状態で、該片方の面とは反対側の面のみが選択的に粗化されたウェーハを作製することができる。 In this way, after roughening the front and back surfaces, only one surface is polished, so that one surface is in a good surface state and only the surface opposite to the one surface is selectively roughened. Wafers can be produced.
また、本発明は、本発明のシリコンウェーハの洗浄方法により、枚葉方式で裏面のみが洗浄されて粗化されているシリコンウェーハを得ることを特徴とするシリコンウェーハの製造方法を提供する。 The present invention also provides a method for producing a silicon wafer, characterized in that a silicon wafer having only its back surface cleaned and roughened by a single wafer method is obtained by the method for cleaning a silicon wafer according to the present invention.
このように、裏面のみ洗浄して粗化されたウェーハを作製することができる。 In this way, a roughened wafer can be produced by cleaning only the back surface.
また、本発明は、洗浄液中の過酸化水素濃度を評価する方法であって、
自然酸化膜を有する調査用シリコンウェーハを、水酸化アンモニウムを含み、かつ、過酸化水素濃度が０～０．１５ｗｔ％の水溶液である洗浄液で洗浄することで粗化された前記調査用シリコンウェーハの表裏面又は裏面の粗化量と、
前記洗浄液の温度と、
前記洗浄液中の水酸化アンモニウム濃度と、
前記洗浄液中の過酸化水素濃度との相関関係を予め取得しておく洗浄液濃度調査工程と、
該洗浄液濃度調査工程で取得しておいた前記相関関係に基づいて、
自然酸化膜を有するシリコンウェーハを、少なくとも水酸化アンモニウムを含む水溶液である評価対象洗浄液で洗浄することで粗化された前記シリコンウェーハの表裏面又は裏面の粗化量と、
前記評価対象洗浄液の温度と、
前記評価対象洗浄液中の水酸化アンモニウム濃度とから、
前記評価対象洗浄液中の過酸化水素濃度を評価する過酸化水素濃度評価工程とを有することを特徴とする洗浄液中の過酸化水素濃度評価方法を提供する。
The present invention also provides a method for evaluating the concentration of hydrogen peroxide in a cleaning liquid, comprising:
A silicon wafer for investigation having a natural oxide film was roughened by cleaning the silicon wafer for investigation with a cleaning liquid that is an aqueous solution containing ammonium hydroxide and having a hydrogen peroxide concentration of 0 to 0.15 wt%. The amount of roughening on the front and back surfaces or the back surface,
the temperature of the cleaning liquid;
ammonium hydroxide concentration in the cleaning solution;
a cleaning solution concentration investigation step of obtaining in advance a correlation with the concentration of hydrogen peroxide in the cleaning solution;
Based on the correlation obtained in the cleaning solution concentration investigation step,
A roughening amount of the front and back surfaces or the back surface of the silicon wafer roughened by cleaning the silicon wafer having a natural oxide film with an evaluation target cleaning liquid that is an aqueous solution containing at least ammonium hydroxide;
the temperature of the cleaning liquid to be evaluated;
From the concentration of ammonium hydroxide in the cleaning liquid to be evaluated,
and a hydrogen peroxide concentration evaluation step of evaluating the hydrogen peroxide concentration in the cleaning liquid to be evaluated.
このような洗浄液中の過酸化水素濃度評価方法であれば、粗化挙動に影響を与える微量の過酸化水素濃度を精度良く評価することができる。 With such a method for evaluating the concentration of hydrogen peroxide in the cleaning liquid, it is possible to accurately evaluate the minute concentration of hydrogen peroxide that affects the roughening behavior.
また、本発明は、洗浄液中の過酸化水素濃度管理方法であって、
本発明の洗浄液中の過酸化水素濃度評価方法により、前記評価対象洗浄液中の過酸化水素濃度を評価し、
該評価結果に基づき、評価後の洗浄液中の過酸化水素濃度を調整することを特徴とする洗浄液中の過酸化水素濃度管理方法を提供する。
The present invention also provides a method for controlling the concentration of hydrogen peroxide in a cleaning liquid, comprising:
Evaluating the concentration of hydrogen peroxide in the cleaning solution to be evaluated by the method for evaluating the concentration of hydrogen peroxide in the cleaning solution of the present invention,
A method for controlling the concentration of hydrogen peroxide in a cleaning liquid is provided, which comprises adjusting the concentration of hydrogen peroxide in the cleaning liquid after evaluation based on the evaluation results.
このような洗浄液中の過酸化水素濃度管理方法であれば、過酸化水素濃度を精度良く管理することができ、粗化を安定して行うことができる。 With such a method for controlling the concentration of hydrogen peroxide in the cleaning liquid, the concentration of hydrogen peroxide can be controlled with high accuracy, and roughening can be stably performed.
本発明のシリコンウェーハの洗浄方法であれば、シリコンウェーハの表裏面又は裏面を粗化することができる。
また、本発明のシリコンウェーハの製造方法であれば、片方の面は良好な面状態で、該片方の面とは反対側の面のみが選択的に粗化されたウェーハを作製することができる。
また、本発明の洗浄液中の過酸化水素濃度評価方法及び管理方法であれば、粗化洗浄に用いる洗浄液中の微量の過酸化水素濃度を精度良く評価及び管理をすることができる。
According to the silicon wafer cleaning method of the present invention, the front and back surfaces or the back surface of the silicon wafer can be roughened.
Further, according to the method for producing a silicon wafer of the present invention, it is possible to produce a wafer in which one surface is in a good surface condition and only the surface opposite to the one surface is selectively roughened. .
Further, with the method for evaluating and controlling the concentration of hydrogen peroxide in the cleaning liquid of the present invention, it is possible to accurately evaluate and control the minute concentration of hydrogen peroxide in the cleaning liquid used for roughening cleaning.
以下、本発明について、実施態様の一例として、図を参照しながら詳細に説明するが、本発明はこれに限定されるものではない。
初めに本発明における粗化現象についてその方法とメカニズムを述べる。図２には、ベア面が露出したＤＳＰ後ウェーハをＳＣ１組成（液組成ＮＨ４ＯＨ：Ｈ２Ｏ２：Ｈ２Ｏ）、洗浄温度及び洗浄時間を変えて洗浄し（水準１から水準１２と表記）、パーティクルカウンターにて粗さ指標であるＨａｚｅ値を取得し、予め洗浄前に取得しておいたＨａｚｅ値との差分を示した。この洗浄後のＨａｚｅ値の増加量（以下、Ｈａｚｅ増加量とも言う）は粗化量の一例である。この値が高いほど面があれていることを示す。併せて、粗化処理なしのＲｅｆと水準５，９のＳＥＭ（走査型電子顕微鏡：Ｓｃａｎｎｉｎｇ Ｅｌｅｃｔｒｏｎｉｃ Ｍｉｃｒｏｓｃｏｐｙ）の表面観察結果も示した。
Hereinafter, the present invention will be described in detail as an example of embodiments with reference to the drawings, but the present invention is not limited thereto.
First, the method and mechanism of the roughening phenomenon in the present invention will be described. In FIG. 2, the post-DSP wafer with the bare surface exposed was cleaned with SC1 composition (liquid composition NH 4 OH:H 2 O 2 :H 2 O), while changing the cleaning temperature and cleaning time (
用いた薬液は２８質量％のアンモニア水（ＮＨ４ＯＨ）、３０質量％の過酸化水素水（Ｈ２Ｏ２）で、それぞれ質量（ｗｔ）％でも表記した。尚、質量％とは洗浄溶液とそれに含まれる溶質（水酸化アンモニウム、過酸化水素）の質量比を百分率で表した濃度で、ｗｔ％とも表記する。 The chemicals used were 28% by mass ammonia water (NH 4 OH) and 30% by mass hydrogen peroxide solution (H 2 O 2 ), each of which is also expressed in mass (wt) %. The mass % is the concentration expressed as a percentage by mass of the cleaning solution and the solute (ammonium hydroxide, hydrogen peroxide) contained therein, and is also expressed as wt %.
水準５，６，８，９，１２において顕著にＨａｚｅ値が増加していることがわかる。さらにＳＥＭ画像を見ると、水準５と水準９は凹凸形状が観察され、Ｒｅｆではこのような凹凸形状は観察されていない。以上より、これらの水準では面が大きくあれており、粗化されていることがわかる。
一方、水準３，４，１１では０．８～０．９ｐｐｍ程度増加しているが、その増加量、即ち粗化度合いが小さく、粗化されているとは言えない。さらにＬＬＳ（局所光散乱欠陥：Ｌｏｃａｌｉｚｅｄ Ｌｉｇｈｔ Ｓｃａｔｔｅｒ）数も非常に多く、欠陥品質が大きく悪化していた。洗浄後の面状態が撥水面であることから、洗浄中にベア面が露出し、Ｓｉのエッチングが顕著に進行し、エッチピットが形成されたためと考えられる。残りの水準では面状態は親水面であったが、Ｈａｚｅ増加量も僅かであった。
At
On the other hand, in
この粗化メカニズムについて詳しく述べる。ＳＣ１洗浄では過酸化水素は酸化剤として機能しＳｉは酸化されＳｉＯ２（自然酸化膜。以下、単に酸化膜とも言う。）が形成される。水酸化アンモニウムは電離反応によりＯＨ－を放出し、このＯＨ－によりウェーハ表面のＳｉＯ２がエッチングされる。一般的な薬液（洗浄液）組成（例えばＮＨ４ＯＨ：Ｈ２Ｏ２：Ｈ２Ｏ＝１：１：１０）では洗浄中は常にウェーハには酸化膜が存在しており、ベア面（Ｓｉ）が露出することなく、形成される酸化膜厚さは洗浄時間に依存せず常に約１ｎｍ程度である。これは酸化速度とエッチング速度のバランスに起因することが知られている。つまり、Ｈ２Ｏ２が所定濃度以上である薬液ではＨ２Ｏ２によるＳｉの酸化速度の方がＯＨ－によるＳｉＯ２のエッチング速度よりも速いために、Ｓｉが露出することなく常にウェーハには酸化膜が存在していると解釈できる。言い換えれば、Ｈ２Ｏ２が所定濃度以下になるとＯＨ－によるエッチング速度の方がＨ２Ｏ２によるＳｉの酸化速度よりも速くなるため、酸化が追い付かず、ＯＨ－によるＳｉのエッチング反応が進行する。このような場合は洗浄後にＳｉが露出しているため、撥水面となる。 This roughening mechanism will be described in detail. In the SC1 cleaning, hydrogen peroxide functions as an oxidizing agent, and Si is oxidized to form SiO 2 (a natural oxide film, hereinafter simply referred to as an oxide film). Ammonium hydroxide releases OH − through an ionization reaction, and this OH − etches SiO 2 on the wafer surface. With a general chemical solution (cleaning solution) composition (for example, NH 4 OH:H 2 O 2 :H 2 O=1:1:10), an oxide film always exists on the wafer during cleaning, and the bare surface (Si) is not exposed, and the thickness of the formed oxide film is always about 1 nm regardless of the cleaning time. It is known that this is due to the balance between the oxidation rate and the etching rate. In other words, in a chemical solution containing H 2 O 2 at a predetermined concentration or higher, the oxidation rate of Si by H 2 O 2 is faster than the etching rate of SiO 2 by OH − , so that Si is not exposed to the wafer at all times. It can be interpreted that an oxide film exists. In other words, when the concentration of H 2 O 2 is below a predetermined concentration, the etching rate by OH − becomes faster than the oxidation rate of Si by H 2 O 2 , so that the oxidation cannot catch up and the etching reaction of Si by OH − proceeds. do. In such a case, since Si is exposed after cleaning, the surface becomes water-repellent.
ここで粗化された水準の薬液組成は、例えば水準５のＮＨ４ＯＨ：Ｈ２Ｏ２：Ｈ２Ｏ＝１：０．４：１０００のようにＨ２Ｏ２比率がＮＨ４ＯＨよりも低いことが分かる。したがって、このような薬液でベア面のシリコンウェーハを洗浄すると、洗浄後の面状態が親水面であることから、初めに酸化反応が進行し酸化膜が形成されるが、酸化速度が遅いため、ＳｉＯ２のエッチングが相対的に優勢となり、ＳｉＯ２がエッチングされ局所的にＳｉが露出された箇所でＳｉのエッチングが進行し、粗化が進行すると考えられる。
Here, the chemical composition of the roughened level has a H 2 O 2 ratio higher than that of
このように本発明における粗化現象は酸化反応とエッチング反応のバランスがある範囲内であると進行する現象である。また安定して粗化を進行させるには、これらの反応が安定した液組成、薬液濃度で洗浄を行う必要がある。 As described above, the roughening phenomenon in the present invention is a phenomenon that progresses when the balance between the oxidation reaction and the etching reaction is within a certain range. In addition, in order to stably progress roughening, it is necessary to wash with a solution composition and a chemical solution concentration in which these reactions are stabilized.
これらを踏まえ、本発明の洗浄方法について述べる。
図１は本発明のシリコンウェーハの洗浄方法の一例を示すフローチャートである。
（工程Ｓ１：洗浄液濃度調査工程）
図１のＳ１では、安定して粗化現象が進行する粗化洗浄条件を選定するための予備試験として洗浄液濃度調査工程を行う。すなわち、粗化量と、洗浄液の温度と、洗浄液中の水酸化アンモニウム濃度と、洗浄液中の過酸化水素濃度との相関関係を予め取得しておく工程である。ここで、上記の粗化量とは、調査用シリコンウェーハ（自然酸化膜がなくベア面が露出している）を洗浄液（水酸化アンモニウムを含み、かつ、過酸化水素濃度が０～０．１５ｗｔ％の水溶液）で洗浄することで粗化された表裏面（又は裏面）の粗化量を言い、例えば、前述したＨａｚｅ増加量とすることができる。Ｈａｚｅ増加量であれば、簡便かつスループット良く粗化挙動、粗化量をモニターできるので好ましい。
なお、上記洗浄液の例としては、過酸化水素濃度が０ｗｔ％のときは、水酸化アンモニウムを含む水溶液とすることができ、また、過酸化水素濃度が０ｗｔ％ではないときは、水酸化アンモニウムと過酸化水素水を含む水溶液とすることができる。
Based on these, the cleaning method of the present invention will be described.
FIG. 1 is a flow chart showing an example of the silicon wafer cleaning method of the present invention.
(Step S1: cleaning liquid concentration investigation step)
In S1 of FIG. 1, a cleaning liquid concentration investigation step is performed as a preliminary test for selecting roughening cleaning conditions under which the roughening phenomenon progresses stably. That is, it is a step of acquiring in advance the correlation among the amount of roughening, the temperature of the cleaning liquid, the concentration of ammonium hydroxide in the cleaning liquid, and the concentration of hydrogen peroxide in the cleaning liquid. Here, the above-mentioned amount of roughening means that the silicon wafer for investigation (the bare surface is exposed without a natural oxide film) was washed with a cleaning solution (containing ammonium hydroxide and having a hydrogen peroxide concentration of 0 to 0.15 wt). % aqueous solution), which means the amount of roughening of the front and back surfaces (or the back surface) roughened by washing, and can be, for example, the above-described haze increase amount. A haze increase amount is preferable because it allows easy monitoring of the roughening behavior and the amount of roughening with high throughput.
Examples of the cleaning solution include an aqueous solution containing ammonium hydroxide when the concentration of hydrogen peroxide is 0 wt%, and an aqueous solution containing ammonium hydroxide when the concentration of hydrogen peroxide is not 0 wt%. An aqueous solution containing hydrogen peroxide can be used.
以下、洗浄液濃度調査工程について、より具体的な例を挙げて説明する。
図３には、ＮＨ４ＯＨ濃度を０．０３，０．１３，０．２５ｗｔ％の３水準でＨ２Ｏ２濃度を変化させ、自然酸化膜がないベア面の調査用シリコンウェーハを８０℃で３ｍｉｎ洗浄したときの、洗浄前後のＨａｚｅ増加量を示した。ＮＨ４ＯＨ濃度が０．０３ｗｔ％の場合については、洗浄後の面状態についても示した（〇は撥水面、●は親水面）。
Hereinafter, the cleaning liquid concentration investigation step will be described with a more specific example.
In FIG. 3, the H 2 O 2 concentration was changed at three levels of 0.03, 0.13, and 0.25 wt% for the NH 4 OH concentration, and the silicon wafer for investigation with a bare surface without a native oxide film was heated at 80°C. The amount of haze increase before and after washing when washing for 3 minutes with is shown. In the case where the NH 4 OH concentration is 0.03 wt %, the surface condition after washing is also shown (○ is a water-repellent surface, ● is a hydrophilic surface).
例えばＮＨ４ＯＨ濃度が０．０３ｗｔ％の場合に着目すると、Ｈ２Ｏ２濃度に依存してＨａｚｅ増加量が変動していることが分かる。Ｈ２Ｏ２濃度が０ｗｔ％や０．００７ｗｔ％ではＨａｚｅ増加量が小さかった。Ｈ２Ｏ２が低濃度過ぎるため、酸化速度が遅すぎてしまい、Ｓｉへのエッチング作用のみが働いたためである。このことはＨ２Ｏ２が低濃度の水準のみ洗浄後の面状態が撥水面（ベアＳｉ面が露出）であることと一致する。
前述のように撥水面の場合はＳｉのエッチングが顕著となりＬＬＳ品質（ＬＬＳ数）が悪化することから、親水面となる範囲で粗化を進行させることが望ましい。Ｈ２Ｏ２濃度が０．０１９ｗｔ％から０．０７８ｗｔ％では面状態は親水面でＨａｚｅ増加量が大きく粗化が進行していた。次いで０．０９ｗｔ％以降は親水面であったが、Ｈａｚｅ増加量が小さくなった。これはＨ２Ｏ２が高濃度過ぎるため、Ｓｉの酸化速度がエッチング速度よりも著しく速くなり、相対的にエッチング作用が弱くなったためである。
For example, focusing on the case where the NH 4 OH concentration is 0.03 wt %, it can be seen that the Haze increase amount fluctuates depending on the H 2 O 2 concentration. When the H 2 O 2 concentration was 0 wt % or 0.007 wt %, the haze increase amount was small. This is because the H 2 O 2 concentration is too low, the oxidation rate is too slow, and only the etching action to Si works. This agrees with the fact that the surface state after washing only at a low concentration level of H 2 O 2 is a water-repellent surface (bare Si surface is exposed).
As described above, in the case of a water-repellent surface, etching of Si becomes significant and the LLS quality (LLS number) deteriorates. When the H 2 O 2 concentration was 0.019 wt % to 0.078 wt %, the surface state was a hydrophilic surface, and the increase in haze was large, and roughening was progressing. After 0.09 wt%, the surface was hydrophilic, but the increase in haze was small. This is because the H 2 O 2 concentration is too high, so that the oxidation rate of Si becomes significantly faster than the etching rate, and the etching action becomes relatively weak.
尚、この洗浄液濃度調査工程は複数水準のＮＨ４ＯＨ濃度、洗浄温度で実施することが好ましい。図示したようにＨａｚｅ増加量はＮＨ４ＯＨ濃度が高いほど大きくなることから、後述する工程Ｓ２で所望のＨａｚｅ増加量（悪化量）を設定する際に、複数水準の調査結果がある方が粗化洗浄条件の選定が容易となる。 It should be noted that this cleaning solution concentration investigation step is preferably carried out at multiple levels of NH 4 OH concentrations and cleaning temperatures. As shown in the figure, the higher the NH 4 OH concentration, the larger the Haze increase amount. Therefore, when setting the desired Haze increase amount (deterioration amount) in step S2 described later, it is more rough if there are multiple levels of investigation results. It becomes easy to select cleaning conditions.
また、本発明者らが調査した結果、Ｈ２Ｏ２濃度が０．１５ｗｔ％より大では、ＮＨ４ＯＨを現実的な範囲で高濃度化しても酸化速度の方が速くなってしまい、粗化が進行しなかったことから、工程Ｓ１では前述したようにＨ２Ｏ２濃度が０～０．１５ｗｔ％以下で行う。 Further, as a result of investigation by the present inventors, when the H 2 O 2 concentration is higher than 0.15 wt %, even if the concentration of NH 4 OH is increased within a practical range, the oxidation rate becomes faster, resulting in Since the quenching did not progress, step S1 is carried out at a H 2 O 2 concentration of 0 to 0.15 wt % or less as described above.
（工程Ｓ２：粗化洗浄条件決定工程）
続いて、Ｓ１の結果に基づき、Ｓ２の粗化洗浄条件決定工程を行う。すなわち、Ｓ１の相関関係に基づいて、所望の粗化量（Ｈａｚｅ増加量）から、洗浄液の温度、洗浄液中の水酸化アンモニウム濃度及び過酸化水素濃度の粗化洗浄条件を決定する工程である。
なお、所望のＨａｚｅ増加量の値については、その都度決定することができる。
(Step S2: Roughening cleaning condition determination step)
Subsequently, based on the result of S1, the roughening cleaning condition determination step of S2 is performed. That is, it is a step of determining the roughening cleaning conditions such as the temperature of the cleaning liquid, the ammonium hydroxide concentration, and the hydrogen peroxide concentration in the cleaning liquid from the desired roughening amount (haze increase) based on the correlation of S1.
Note that the desired Haze increase amount value can be determined on a case-by-case basis.
この工程では、特には、Ｓ１で得られた相関関係からＨ２Ｏ２濃度の変動に対するＨａｚｅ増加量の変動が安定した粗化洗浄条件を選定することが目的である。
図３において、ＮＨ４ＯＨ濃度が０．０３ｗｔ％の場合では、０．０３２～０．０７８ｗｔ％の範囲でＨａｚｅ増加量の変動が小さく、安定していることが分かる。この場合、例えば０．０５ｗｔ％のＨ２Ｏ２濃度にすることで、意図せず洗浄液中のＨ２Ｏ２濃度が変動したとしても、その変動に対してＨａｚｅ増加量の変動は比較的小さく安定しているので、所望のＨａｚｅ増加量から大きく外れることもなく、より安定して所望のＨａｚｅ増加量で粗化を進行させることができる。このように、粗化洗浄条件の一つとして選定するＨ２Ｏ２濃度は、Ｈ２Ｏ２濃度の変動に対するＨａｚｅ増加量の変動が比較的小さな値（所定値）以下に収まるようなＨ２Ｏ２濃度の範囲から決定すると好ましい。この所定値は、要求される精度等に応じて、０以上の数値から適宜設定することができる。
The purpose of this step is to select, from the correlation obtained in S1, roughening cleaning conditions in which the Haze increment is stable with respect to the H 2 O 2 concentration.
It can be seen from FIG. 3 that when the NH 4 OH concentration is 0.03 wt %, the increase in haze fluctuates little and is stable within the range of 0.032 to 0.078 wt %. In this case, for example, by setting the H 2 O 2 concentration to 0.05 wt %, even if the H 2 O 2 concentration in the cleaning solution unintentionally fluctuates, the Haze increase amount fluctuates relatively little with respect to the fluctuation. Since it is stable, roughening can be progressed more stably with the desired increase in haze without greatly deviating from the desired increase in haze. In this way, the H 2 O 2 concentration selected as one of the roughening cleaning conditions is such that the variation in the Haze increment with respect to the variation in the H 2 O 2 concentration falls within a relatively small value (predetermined value) or less . It is preferably determined from a range of O2 concentrations. This predetermined value can be appropriately set from a numerical value of 0 or more according to the required accuracy and the like.
次にＮＨ４ＯＨ濃度が０．１３ｗｔ％、０．２５ｗｔ％の場合に着目すると、Ｈ２Ｏ２濃度が小さい場合は酸化速度が遅く、エッチング優勢となりＨａｚｅ増加量が大きく変動しており、不安定であると判断できる。したがって、この範囲で粗化を行うことは好ましくない。ＮＨ４ＯＨ濃度が高いほど、エッチング速度が速くなったため、０．０３ｗｔ％よりもその変動が大きくなっていると考えられる。
ただ、Ｈ２Ｏ２濃度が高くなると、０．０３ｗｔ％の場合と同様に、Ｈａｚｅ増加量が安定となるＨ２Ｏ２濃度範囲が存在していることが分かる。ＮＨ４ＯＨ濃度が異なるとＨａｚｅ増加量が安定するために必要なＨ２Ｏ２濃度範囲が変化するため、予めＨ２Ｏ２の適正濃度範囲を求めておくことでより安定して粗化を進行させることができる。
Next, focusing on the case where the NH 4 OH concentration is 0.13 wt % and 0.25 wt %, when the H 2 O 2 concentration is small, the oxidation rate is slow, and the etching is dominant, and the increase in haze fluctuates greatly. can be judged to be stable. Therefore, roughening in this range is not preferable. It is believed that the higher the NH 4 OH concentration, the faster the etching rate, and therefore the variation is greater than 0.03 wt %.
However, when the H 2 O 2 concentration increases, it can be seen that there is a H 2 O 2 concentration range in which the Haze increase is stable, as in the case of 0.03 wt%. If the NH 4 OH concentration is different, the H 2 O 2 concentration range necessary for stabilizing the Haze increase amount will change . can proceed.
また、ＮＨ４ＯＨ濃度が高いほど、Ｈａｚｅ増加量が大きくなることから、ＮＨ４ＯＨ濃度を調整することで、所望の粗さ（Ｈａｚｅ増加量）を形成させることもできる。例えばＨａｚｅ増加量が５ｐｐｍのウェーハを得たい場合は、ＮＨ４ＯＨ濃度が０．０３ｗｔ％でＨ２Ｏ２濃度を０．０５ｗｔ％とし、８０℃かつ３ｍｉｎで粗化洗浄条件を選定することができる。一方、例えばＨａｚｅ増加量を３０ｐｐｍのウェーハを得たい場合は、ＮＨ４ＯＨ濃度を０．２５ｗｔ％で、Ｈ２Ｏ２濃度を０．０７ｗｔ％とし、８０℃かつ３ｍｉｎで粗化洗浄条件を選定することができる。このようにＨ２Ｏ２濃度に対するＨａｚｅ増加量の変動を把握しておくことで、より安定して粗化を進行させる粗化洗浄条件を選定することができる。 Moreover, since the haze increase amount increases as the NH 4 OH concentration increases, desired roughness (haze increase amount) can be formed by adjusting the NH 4 OH concentration. For example, when it is desired to obtain a wafer with a haze increase of 5 ppm, it is possible to select roughening cleaning conditions of NH 4 OH concentration of 0.03 wt %, H 2 O 2 concentration of 0.05 wt %, and 80° C. for 3 minutes. can. On the other hand, if it is desired to obtain a wafer with a haze increase of 30 ppm, the NH 4 OH concentration is 0.25 wt %, the H 2 O 2 concentration is 0.07 wt %, and roughening cleaning conditions are selected at 80° C. for 3 minutes. can do. By grasping the variation in the Haze increase amount with respect to the H 2 O 2 concentration in this way, it is possible to select the roughening cleaning conditions that allow the roughening to proceed more stably.
また、この工程Ｓ２では、後述する工程Ｓ３における洗浄後の粗化対象シリコンウェーハ表面に、Ｓ３での洗浄中に形成された自然酸化膜が残るような粗化洗浄条件を決定すれば、粗化度合いもより一層十分なものとすることができるため好ましい。親水面の表面を得ることもでき、ＬＬＳ数が悪化するのを防ぐこともできる。 Further, in this step S2, if a roughening cleaning condition is determined such that a natural oxide film formed during cleaning in S3 remains on the surface of the silicon wafer to be roughened after cleaning in step S3, which will be described later, roughening can be performed. It is preferable because the degree can be made more sufficient. A hydrophilic surface can also be obtained, and deterioration of the LLS number can be prevented.
続いて、洗浄液の温度（洗浄温度）の影響について述べる。
図４にはＮＨ４ＯＨ濃度が０．０３ｗｔ％、０．２５ｗｔ％で洗浄時間３ｍｉｎとして、洗浄温度を４５℃、６０℃で洗浄した場合のＨａｚｅ増加量の変動を示した。全３水準ともＨａｚｅ増加量が大きくなる条件はあるが、８０℃の場合の図３に比べて、前述のようなＨａｚｅ増加量が安定したＨ２Ｏ２濃度範囲が狭いことが分かる。したがって、洗浄温度を８０℃以上で、Ｓ１の洗浄液濃度調査工程を実施したり、Ｓ２の粗化洗浄条件決定工程での選定を行った方がより安定した粗化洗浄条件を選定しやすいと解釈できる。この理由としては温度が高い方が過酸化水素の酸化作用が安定するためと考えられる。洗浄温度の上限値は特には決められないが、例えば９０℃もあれば十分である。
Next, the influence of the temperature of the cleaning liquid (cleaning temperature) will be described.
FIG. 4 shows the change in the amount of haze increase when washing was performed at NH 4 OH concentrations of 0.03 wt % and 0.25 wt %, with a washing time of 3 minutes and washing temperatures of 45° C. and 60° C., respectively. All the three levels have conditions in which the haze increase amount is large, but compared to FIG . Therefore, it is interpreted that it is easier to select a more stable roughening cleaning condition if the cleaning temperature is set to 80° C. or higher and the cleaning solution concentration investigation step of S1 is carried out or selection is performed in the roughening cleaning condition determination step of S2. can. The reason for this is thought to be that the higher the temperature, the more stable the oxidizing action of hydrogen peroxide. Although the upper limit of the washing temperature is not particularly determined, 90° C., for example, is sufficient.
ただし、必ずしも８０℃やそれ以上である必要はなく、６０℃以下でもＨａｚｅ増加量が大きくなる領域が存在することから、粗化を進行させることは可能で、例えば薬液ライフを短くすることなどで洗浄液中のＨ２Ｏ２濃度の変動に起因したＨａｚｅ増加量のバラツキを抑制することもできる。 However, the temperature does not necessarily need to be 80°C or higher, and there is a region where the Haze increase amount is large even at 60°C or lower, so it is possible to proceed with roughening, for example, by shortening the chemical solution life. It is also possible to suppress variations in the amount of Haze increase due to variations in the H 2 O 2 concentration in the cleaning liquid.
続いて、洗浄時間の影響について述べる。
図５には、ＮＨ４ＯＨ濃度が０．０３ｗｔ％、Ｈ２Ｏ２濃度が０．０５ｗｔ％の洗浄液で、洗浄温度が８０℃で、洗浄時間を３０，６０，１８０，３６０ｓｅｃで洗浄した際のＨａｚｅ増加量を示した。洗浄時間が長いほど、Ｈａｚｅ増加量が増加していることが分かる。したがって、ＮＨ４ＯＨ濃度、Ｈ２Ｏ２濃度、洗浄温度の他、さらには洗浄時間を調整することで粗化度合いを調整することもできる。上述のようにＮＨ４ＯＨ濃度を調整しても良いし、洗浄時間を調整して粗化度合いを制御しても良く、適宜必要に応じて使い分ければよい。このように、Ｓ１での相関関係取得やＳ２での粗化洗浄条件の決定を、洗浄時間をさらに考慮して行うことも可能である。
Next, the effect of cleaning time will be described.
FIG. 5 shows the results of washing with a washing solution having an NH 4 OH concentration of 0.03 wt % and an H 2 O 2 concentration of 0.05 wt %, at a washing temperature of 80° C., and for washing times of 30, 60, 180, and 360 sec. Haze increase amount of. It can be seen that the longer the washing time, the greater the increase in haze. Therefore, the degree of roughening can be adjusted by adjusting the NH 4 OH concentration, H 2 O 2 concentration, cleaning temperature, and cleaning time. The NH 4 OH concentration may be adjusted as described above, or the cleaning time may be adjusted to control the degree of roughening. In this way, it is possible to further consider the cleaning time when acquiring the correlation in S1 and determining the roughening cleaning conditions in S2.
（工程Ｓ３：粗化洗浄工程）
続いてＳ３の粗化洗浄工程では、Ｓ２で決定した粗化洗浄条件で、自然酸化膜がないベア面の粗化対象シリコンウェーハを洗浄する。該洗浄により、粗化対象シリコンウェーハの表裏面（又は裏面）を粗化する工程である。このように、前述したＳ１、Ｓ２を経てこのＳ３の工程を行うことで、前述した所望のＨａｚｅ増加量の粗化ウェーハを確実に得ることができる。しかも、特には、所望のＨａｚｅ増加量から大きく外れることがなく（すなわち、Ｈａｚｅ増加量のバラツキが小さく）、安定した粗化度合いで作製することができる。
(Step S3: roughening cleaning step)
Subsequently, in the roughening cleaning step of S3, the roughening target silicon wafer having a bare surface without a natural oxide film is cleaned under the roughening cleaning conditions determined in S2. This cleaning is a step of roughening the front and rear surfaces (or the rear surface) of the silicon wafer to be roughened. Thus, by performing the step of S3 after the steps of S1 and S2, it is possible to reliably obtain the roughened wafer having the desired increase in haze. Moreover, in particular, it is possible to produce a stable degree of roughening without greatly deviating from the desired increase in haze (that is, the variation in increase in haze is small).
続いて、本発明の洗浄を実施する際の洗浄方式について述べる。現在、ウェーハの洗浄方式は大半が薬液や純水などの液体を使用するものでウェット洗浄と呼ばれる。その中で主な方式としては一度に多くのウェーハをまとめて洗浄するバッチ方式とウェーハを１枚ずつ処理する枚葉方式に分かれる。バッチ方式は装置構成上ウェーハの表面及び裏面の両方が薬液に浸漬するため、本発明の洗浄を行うと表裏面が粗化される。対して、枚葉方式はウェーハを回転させながら、薬液をスプレーするため、ウェーハの片面のみを洗浄することができる。本発明者らが調査したところ、本発明ではバッチ方式及び枚葉方式どちらの方式でも粗化することができる。ウェーハの製造工程を考慮し、適宜方式を選定することができる。 Next, a cleaning method for carrying out the cleaning of the present invention will be described. Currently, most wafer cleaning methods use chemicals, pure water, and other liquids, and are called wet cleaning. Among them, the main methods are divided into a batch method in which many wafers are cleaned at once and a single wafer method in which wafers are processed one by one. In the batch method, both the front and back surfaces of the wafer are immersed in the chemical liquid due to the equipment configuration, so that the front and back surfaces are roughened when the cleaning of the present invention is performed. On the other hand, in the single-wafer method, the chemical solution is sprayed while rotating the wafer, so only one side of the wafer can be cleaned. According to investigations conducted by the present inventors, roughening can be performed by either a batch method or a single wafer method in the present invention. An appropriate method can be selected in consideration of the wafer manufacturing process.
上述のように裏面のみが粗いウェーハを作製するには、枚葉方式の場合は裏面のみを洗浄すればよく、バッチ方式の場合は表裏面両方ともが粗化されてしまう。そこで本発明のシリコンウェーハの製造方法のように、本発明の洗浄方法により洗浄した後、研磨工程により、特には表面側の品質を良好にすることが望ましい。
例えば、本発明のシリコンウェーハの洗浄方法をバッチ式の洗浄機で行ってシリコンウェーハの表裏面共に粗化し、その後ＣＭＰ加工のような片面研磨を片方の面（すなわち表面）に対して行うことで、該片方の面とは反対側の面（すなわち裏面）のみが選択的に粗化されたウェーハを製造することができる。
このようなウェーハであれば、ウェット環境下でもチャック不良を引き起こさず、安定した製造が可能となる。
As described above, in order to produce a wafer having a rough back surface only, only the back surface needs to be cleaned in the case of the single-wafer method, while both the front and back surfaces are roughened in the case of the batch method. Therefore, as in the method for producing a silicon wafer of the present invention, it is desirable to improve the quality of the surface side, in particular, by polishing after cleaning by the cleaning method of the present invention.
For example, the silicon wafer cleaning method of the present invention is performed by a batch-type cleaning machine to roughen both the front and back surfaces of the silicon wafer, and then one side polishing such as CMP processing is performed on one side (that is, the front side). , it is possible to produce wafers that are selectively roughened only on the side opposite to the one side (ie the back side).
With such a wafer, chuck failure does not occur even in a wet environment, and stable production is possible.
続いて、前述した本発明の洗浄方法において粗化に用いる洗浄液に関し、該洗浄液中の過酸化水素濃度を評価する方法及び管理する方法について述べる。
上述のように本発明の粗化挙動は過酸化水素濃度に強く依存することから、過酸化水素濃度を管理することでより安定的に粗化を進行させることができる。一般的なＳＣ１洗浄液の薬液濃度を評価する方法としては吸光度や屈折率による濃度測定方法があり、その精度も高いことが知られている。しかし、本発明者らが、粗化洗浄を行うため、例えばＮＨ４ＯＨが０．２５ｗｔ％、Ｈ２Ｏ２濃度が０．０７ｗｔ％で配合した洗浄液を吸光度方式の濃度計にて濃度を計測したところ、ＮＨ４ＯＨ濃度は０．２４ｗｔ％と計測されたが、Ｈ２Ｏ２濃度は検出下限値以下となり、計測できなかった。
Next, regarding the cleaning solution used for roughening in the cleaning method of the present invention, methods for evaluating and controlling the concentration of hydrogen peroxide in the cleaning solution will be described.
As described above, the roughening behavior of the present invention strongly depends on the concentration of hydrogen peroxide. Therefore, by controlling the concentration of hydrogen peroxide, the roughening can be progressed more stably. As a general method for evaluating the chemical solution concentration of the SC1 cleaning solution, there is a concentration measurement method based on absorbance or refractive index, and it is known that the accuracy thereof is high. However, in order to perform roughening cleaning, the present inventors measured the concentration of a cleaning solution containing, for example, 0.25 wt% NH 4 OH and 0.07 wt% H 2 O 2 using an absorbance densitometer. As a result, the NH 4 OH concentration was measured to be 0.24 wt%, but the H 2 O 2 concentration was below the detection limit and could not be measured.
そこで本発明者らは上述した粗化挙動を利用してＨ２Ｏ２濃度を評価及び管理できないか鋭意検討を行った。図６は本発明の洗浄液中の過酸化水素濃度の評価方法および管理方法のフローである。
（工程Ｓ１１：洗浄液濃度調査工程）
初めにＳ１１の洗浄液濃度調査工程のように、調査用シリコンウェーハ（自然酸化膜を有する）について、粗化量（例えばＨａｚｅ増加量）と、洗浄液（水酸化アンモニウムを含み、かつ、過酸化水素濃度が０～０．１５ｗｔ％の水溶液）の温度と、洗浄液中の水酸化アンモニウム濃度と、洗浄液中の過酸化水素濃度との相関関係を取得しておく工程である。
なお、上記洗浄液の例としては、過酸化水素濃度が０ｗｔ％のときは、水酸化アンモニウムを含む水溶液とすることができ、また、過酸化水素濃度が０ｗｔ％ではないときは、水酸化アンモニウムと過酸化水素水を含む水溶液（ＳＣ１洗浄液）とすることができる。
Therefore, the present inventors have earnestly investigated whether the H 2 O 2 concentration can be evaluated and controlled using the above-described roughening behavior. FIG. 6 is a flowchart of the method for evaluating and controlling the concentration of hydrogen peroxide in the cleaning solution of the present invention.
(Step S11: cleaning liquid concentration investigation step)
First, as in the cleaning liquid concentration investigation step of S11, for the silicon wafer for investigation (having a native oxide film), the amount of roughening (for example, the amount of haze increase) and the cleaning liquid (containing ammonium hydroxide and hydrogen peroxide concentration of 0 to 0.15 wt %), the ammonium hydroxide concentration in the cleaning liquid, and the hydrogen peroxide concentration in the cleaning liquid.
Examples of the cleaning solution include an aqueous solution containing ammonium hydroxide when the concentration of hydrogen peroxide is 0 wt%, and an aqueous solution containing ammonium hydroxide when the concentration of hydrogen peroxide is not 0 wt%. An aqueous solution (SC1 cleaning solution) containing hydrogen peroxide can be used.
ここで、前述した本発明のシリコンウェーハの洗浄方法における工程Ｓ１の洗浄液濃度調査工程（調査用シリコンウェーハとして自然酸化膜がないものを使用）とは異なり、本発明の洗浄液中の過酸化水素濃度評価方法のこの工程Ｓ１１の洗浄液濃度調査工程で自然酸化膜を有するものを使用する理由は以下の通りである。
洗浄方法では、特には過酸化水素量の変動に対する粗化量のバラツキが小さく、安定した領域を求めるため図３のような傾向が得られるように自然酸化膜がないものを用いたが、この場合は逆に言えば粗化量に対応する過酸化水素濃度を一義的に求められなくなる。一方で自然酸化膜を有する場合は、後述するように過酸化水素濃度が高いほど粗化量が減少する傾向があり、粗化量から過酸化水素濃度を一義的に求めることができるからである。
Here, unlike the cleaning liquid concentration investigation step of step S1 in the silicon wafer cleaning method of the present invention described above (a silicon wafer without a natural oxide film is used for investigation), the hydrogen peroxide concentration in the cleaning liquid of the present invention is The reason for using the one having a natural oxide film in the cleaning solution concentration investigation step S11 of the evaluation method is as follows.
In the cleaning method, in order to find a stable region with small variations in the amount of roughening with respect to fluctuations in the amount of hydrogen peroxide, a method without a natural oxide film was used so as to obtain the tendency shown in FIG. In other words, the concentration of hydrogen peroxide corresponding to the amount of roughening cannot be determined uniquely. On the other hand, in the case of having a natural oxide film, as will be described later, the higher the hydrogen peroxide concentration, the more the amount of roughening tends to decrease, and the hydrogen peroxide concentration can be uniquely determined from the amount of roughening. .
以下、洗浄液濃度調査工程について、より具体的な例を挙げて説明する。
まず、自然酸化膜を有する調査用シリコンウェーハを用意し、Ｈａｚｅ増加量を算出するため、洗浄前にパーティクルカウンターにてＨａｚｅ値を取得する。
なお、自然酸化膜の形成方法としては、一般的なＳＣ１洗浄やオゾン水洗浄が挙げられる。これらの洗浄は洗浄後に自然酸化膜が形成されれば特に制限されない。ＳＣ１洗浄液の混合比（体積比）は例えばＮＨ４ＯＨ：Ｈ２Ｏ２：Ｈ２Ｏ＝１：１：１０、温度は３０～８０℃、洗浄時間は９０～３６０秒が好ましい。オゾン水の濃度は３～２５ｐｐｍの範囲で、温度は１０～３０℃、洗浄時間は６０～３６０秒が好ましい。
Hereinafter, the cleaning liquid concentration investigation step will be described with a more specific example.
First, a silicon wafer for investigation having a natural oxide film is prepared, and the haze value is obtained with a particle counter before cleaning in order to calculate the increase in haze.
As a method for forming a natural oxide film, general SC1 cleaning and ozone water cleaning can be used. These cleaning methods are not particularly limited as long as a natural oxide film is formed after cleaning. The mixing ratio (volume ratio) of the SC1 cleaning liquid is preferably NH 4 OH:H 2 O 2 :H 2 O=1:1:10, the temperature is preferably 30 to 80° C., and the cleaning time is preferably 90 to 360 seconds. The concentration of ozone water is preferably in the range of 3-25 ppm, the temperature is preferably 10-30° C., and the cleaning time is preferably 60-360 seconds.
次に、前述した洗浄液を種々の温度で用意し、ＮＨ４ＯＨ濃度やＨ２Ｏ２濃度を振って（さらには必要に応じて洗浄時間も振って）、自然酸化膜が存在する調査用シリコンウェーハを洗浄して表裏面（又は裏面）を粗化した後、パーティクルカウンターにてＨａｚｅ値を取得する。
図７は、洗浄温度が８０℃で、洗浄時間３ｍｉｎ、洗浄液中のＮＨ４ＯＨ濃度が０．０３ｗｔ％の場合のＨ２Ｏ２濃度に対するＨａｚｅ増加量を示した結果である。ベア面の場合（例えば図３）とは傾向が異なり、Ｈ２Ｏ２濃度が高いほど、Ｈａｚｅ増加量が減少する傾向が分かる。このように、予め、洗浄温度と、ＮＨ４ＯＨ濃度と、Ｈ２Ｏ２濃度と、Ｈａｚｅ増加量との相関関係を取得しておく。
尚、本発明者らが調査した結果、Ｈ２Ｏ２濃度が０．１５ｗｔ％より大きい場合では、Ｈａｚｅ増加量はほぼ０に近い値となり、指標とすることが難しい。一方、本発明はＨ２Ｏ２濃度が０．１５ｗｔ％以下の洗浄液に対する評価方法であり、このような微量の場合でも精度よくＨ２Ｏ２濃度を評価することでできる。
Next, the aforementioned cleaning solutions were prepared at various temperatures, and the concentrations of NH 4 OH and H 2 O 2 were varied (and the cleaning time was also varied as necessary) to obtain silicon for investigation in which a native oxide film was present. After the wafer is washed to roughen the front and back surfaces (or the back surface), the haze value is obtained with a particle counter.
FIG. 7 shows the increase in haze with respect to the H 2 O 2 concentration when the cleaning temperature is 80° C., the cleaning time is 3 minutes, and the NH 4 OH concentration in the cleaning liquid is 0.03 wt %. The trend is different from that of the bare surface (for example, FIG. 3), and it can be seen that the higher the H 2 O 2 concentration, the smaller the increase in haze. In this way, the correlation among the cleaning temperature, NH 4 OH concentration, H 2 O 2 concentration, and Haze increase amount is obtained in advance.
As a result of investigation by the present inventors, when the H 2 O 2 concentration is more than 0.15 wt %, the Haze increase amount becomes a value close to 0, which is difficult to use as an index. On the other hand, the present invention is an evaluation method for a cleaning liquid having an H 2 O 2 concentration of 0.15 wt % or less, and can accurately evaluate the H 2 O 2 concentration even in such a very small amount.
（工程Ｓ１２：過酸化水素濃度評価工程）
次にＳ１２の過酸化水素濃度評価工程のように、Ｈ２Ｏ２濃度を計測したい評価対象洗浄液（少なくとも水酸化アンモニウムを含む水溶液）で、Ｓ１１のときと同様の自然酸化膜を有するシリコンウェーハを、Ｓ１１で取得した相関関係のうちの所定の洗浄温度（さらには所定の洗浄時間）で洗浄し、Ｈａｚｅ増加量を取得する。なお、ＮＨ４ＯＨ濃度は例えば従来法により測定して求めておいても良い。
特には、洗浄温度（および洗浄時間）を予め設定しておき、Ｓ１１とＳ１２の工程を同じ洗浄温度（および洗浄時間）で行うと簡便である。
次いで、Ｓ１１で求めた相関関係に基づいて、上記で得られたＨａｚｅ増加量、洗浄温度（および洗浄時間）、ＮＨ４ＯＨ濃度から、Ｈ２Ｏ２濃度を評価することができる。
(Step S12: Hydrogen Peroxide Concentration Evaluation Step)
Next, as in the hydrogen peroxide concentration evaluation step of S12, a silicon wafer having a natural oxide film similar to that in S11 is cleaned with an evaluation target cleaning solution (aqueous solution containing at least ammonium hydroxide) whose H 2 O 2 concentration is to be measured. , wash at a predetermined washing temperature (further, a predetermined washing time) in the correlation obtained in S11, and obtain the haze increase amount. Incidentally, the NH 4 OH concentration may be obtained by measuring, for example, by a conventional method.
In particular, it is convenient to preset the washing temperature (and washing time) and perform the steps of S11 and S12 at the same washing temperature (and washing time).
Then, based on the correlation obtained in S11, the H 2 O 2 concentration can be evaluated from the above-obtained Haze increment, cleaning temperature (and cleaning time), and NH 4 OH concentration.
（工程Ｓ１３：過酸化水素濃度管理工程）
また、さらにはＳ１３の過酸化水素濃度管理工程のように、Ｓ１２で得られた評価結果に応じて、洗浄液中の過酸化水素濃度を調整することもできる。
例えば、初めにＮＨ４ＯＨ濃度が０．０３ｗｔ％、Ｈ２Ｏ２濃度が０．０５ｗｔ％となるように配合した洗浄液を用いて、所定時間洗浄した後、本発明の評価方法でＨ２Ｏ２濃度を評価したところ、０．０４ｗｔ％と判定された場合は、Ｈ２Ｏ２濃度が０．０５ｗｔ％となるように過酸化水素水を注加することができる。逆に０．０６ｗｔ％と判定された場合はＨ２Ｏ２濃度が０．０５ｗｔ％となるように純水を注加することができる。このような管理方法を行うことで、薬液ライフを長くすることもでき、Ｈａｚｅ増加量が安定した粗化ウェーハを製造することができる。
このようにして、洗浄液中の０～０．１５ｗｔ％という微量のＨ２Ｏ２濃度を精度良く評価し、また管理することができ、ひいては所望の粗化ウェーハを安定して製造可能である。
(Step S13: Hydrogen Peroxide Concentration Control Step)
Furthermore, like the hydrogen peroxide concentration control step of S13, the concentration of hydrogen peroxide in the cleaning liquid can be adjusted according to the evaluation result obtained in S12.
For example, first, after washing for a predetermined time using a cleaning solution containing NH 4 OH concentration of 0.03 wt % and H 2 O 2 concentration of 0.05 wt %, H 2 O is removed by the evaluation method of the present invention. 2 concentration is determined to be 0.04 wt %, hydrogen peroxide solution can be added so that the H 2 O 2 concentration becomes 0.05 wt %. Conversely, when it is determined to be 0.06 wt %, pure water can be added so that the H 2 O 2 concentration becomes 0.05 wt %. By performing such a management method, the chemical solution life can be lengthened, and a roughened wafer with a stable increase in haze can be manufactured.
In this way, the minute H 2 O 2 concentration of 0 to 0.15 wt % in the cleaning liquid can be accurately evaluated and controlled, and as a result, the desired roughened wafers can be produced stably.
以下、本発明を実施例に基づきさらに説明するが、これらの実施例は例示的に示されるもので限定的に解釈されるべきではない。
（実施例１）
図１の本発明の洗浄方法に示すように、初めに予備試験のＳ１の洗浄液濃度調査工程を実施した。
ＫＬＡ社製パーティクルカウンター ＳＰ３にて、ＤＳＰ加工後の自然酸化膜のないベア面のシリコンウェーハ（調査用シリコンウェーハ）のＨａｚｅ値を取得した。続いて、２８質量％のアンモニア水（ＮＨ４ＯＨ）と、さらには必要に応じて３０質量％の過酸化水素水（Ｈ２Ｏ２）を用いて、洗浄液の温度が８０℃で、ＮＨ４ＯＨ濃度が０．０３ｗｔ％と０．２５ｗｔ％の２水準の洗浄液を準備し、Ｈ２Ｏ２濃度を０～０．１５ｗｔ％の範囲内で変えて上記のベア面のシリコンウェーハを洗浄時間３ｍｉｎで洗浄した後、ＳＰ３にてＨａｚｅ値を取得し、洗浄前後の差分から粗化量の指標であるＨａｚｅ増加量を算出した。
洗浄温度が８０℃の場合における、Ｈａｚｅ増加量、ＮＨ４ＯＨ濃度、およびＨ２Ｏ２濃度の相関関係を図８に示す。
The present invention will be further described below based on examples, but these examples are shown by way of illustration and should not be construed as limiting.
(Example 1)
As shown in the cleaning method of the present invention in FIG. 1, first, a cleaning liquid concentration investigation step of S1 of a preliminary test was carried out.
A Haze value of a bare surface silicon wafer (silicon wafer for investigation) having no natural oxide film after DSP processing was obtained using a particle counter SP3 manufactured by KLA. Subsequently, 28% by mass of ammonia water (NH 4 OH) and, if necessary, 30% by mass of hydrogen peroxide solution (H 2 O 2 ) are used to wash the NH 4 at a temperature of 80° C. Two levels of cleaning solutions with OH concentrations of 0.03 wt % and 0.25 wt % were prepared, and the above bare silicon wafers were cleaned for 3 min by changing the H 2 O 2 concentration within the range of 0 to 0.15 wt %. After washing with , the haze value was obtained in SP3, and the increase in haze, which is an index of the amount of roughening, was calculated from the difference between before and after washing.
FIG. 8 shows the correlation between the haze increase amount, the NH 4 OH concentration, and the H 2 O 2 concentration when the washing temperature is 80°C.
次にＳ２の粗化洗浄条件決定工程を実施した。
Ｈａｚｅ増加量が１０ｐｐｍと３０ｐｐｍの２水準のウェーハを作製することを目的とした。Ｓ１で求めた図８の相関関係からこれらのＨａｚｅ増加量を得られるような粗化洗浄条件を決定した。
１０ｐｐｍについては、ＮＨ４ＯＨ濃度が０．０３ｗｔ％の場合に着目すると、Ｈ２Ｏ２濃度が約０．０３～０．０８ｗｔ％範囲でＨａｚｅ増加量が約５～６ｐｐｍ程度と安定した範囲が存在していること分かる。したがって、次のＳ３の工程で、粗化対象シリコンウェーハに対して用いる洗浄液は、ＮＨ４ＯＨ濃度を０．０３ｗｔ％とし、Ｈ２Ｏ２濃度を０．０３～０．０８ｗｔ％の範囲内のうちの０．０５ｗｔ％とし、洗浄温度は８０℃とした。洗浄時間については、Ｈａｚｅ増加量と洗浄時間には正の相関があり、３ｍｉｎで５～６ｐｐｍのＨａｚｅ増加量であることを踏まえ、洗浄時間を３ｍｉｎの２倍の６ｍｉｎと設定した。この設定により、約１０ｐｐｍのＨａｚｅ増加量が見込まれる。
Next, the roughening washing condition determination step of S2 was performed.
The object was to produce wafers with two levels of haze increase amounts of 10 ppm and 30 ppm. Roughening cleaning conditions for obtaining these haze increments were determined from the correlation of FIG. 8 obtained in S1.
Regarding 10 ppm, focusing on the case where the NH 4 OH concentration is 0.03 wt%, the H 2 O 2 concentration is in the range of about 0.03 to 0.08 wt%, and the haze increase amount is about 5 to 6 ppm, which is a stable range. I know it exists. Therefore, in the next step S3, the cleaning liquid used for the silicon wafer to be roughened has an NH 4 OH concentration of 0.03 wt % and an H 2 O 2 concentration of 0.03 to 0.08 wt %. 0.05 wt% of the total, and the washing temperature was 80°C. Regarding the cleaning time, there is a positive correlation between the haze increase amount and the cleaning time, and based on the fact that the haze increase amount is 5 to 6 ppm at 3 minutes, the cleaning time was set to 6 minutes, which is twice the 3 minutes. A haze increase of about 10 ppm is expected with this setting.
３０ｐｐｍについては、ＮＨ４ＯＨ濃度が０．２５ｗｔ％の場合に着目すると、Ｈ２Ｏ２濃度が０．０５～０．０９ｗｔ％の範囲でＨａｚｅ増加量が約３０ｐｐｍと安定している。このことから、洗浄液は、ＮＨ４ＯＨ濃度を０．２５ｗｔ％とし、Ｈ２Ｏ２濃度を０．０５～０．０９ｗｔ％の範囲内の０．０７ｗｔ％とし、洗浄温度は８０℃とした。洗浄時間は、３ｍｉｎで３０ｐｐｍのＨａｚｅ増加量であることから、Ｓ１のときと同様に３ｍｉｎとした。 Regarding 30 ppm, focusing on the case where the NH 4 OH concentration is 0.25 wt %, the increase in haze is stable at about 30 ppm when the H 2 O 2 concentration is in the range of 0.05 to 0.09 wt %. For this reason, the cleaning liquid had an NH 4 OH concentration of 0.25 wt %, an H 2 O 2 concentration of 0.07 wt % in the range of 0.05 to 0.09 wt %, and a cleaning temperature of 80°C. The washing time was set to 3 minutes as in the case of S1, since the haze increase amount was 30 ppm at 3 minutes.
次いで、Ｓ３の粗化洗浄工程を実施した。
Ｓ２で決定したＨａｚｅ増加量が１０ｐｐｍと３０ｐｐｍ狙いの２水準の粗化洗浄条件にて、ＤＳＰ加工後の自然酸化膜がないベア面のシリコンウェーハ（粗化対象シリコンウェーハ）を各水準５枚をバッチ式洗浄機で洗浄して両面を粗化し、ＳＰ３にてＨａｚｅ値を取得し、Ｈａｚｅ増加量を算出した。１０ｐｐｍ狙いのウェーハのＨａｚｅ増加量の平均値は１０．７ｐｐｍ、３０ｐｐｍ狙いのウェーハのＨａｚｅ増加量の平均値は３１．２ｐｐｍとなり、狙いＨａｚｅ増加量と同等の粗さを形成したウェーハを作製することができた。またＬＬＳ品質は１０ｐｐｍ狙いのウェーハでは１ｐｃｓ、３０ｐｐｍ狙いのウェーハでは０ｐｃｓとなり良好であった。
Then, the roughening cleaning step of S3 was performed.
Under two levels of roughening cleaning conditions, aiming for a haze increment of 10 ppm and 30 ppm determined in S2, 5 bare surface silicon wafers (silicon wafers to be roughened) after DSP processing with no natural oxide film for each level. Both surfaces were roughened by washing with a batch type washing machine, the haze value was obtained in SP3, and the increase in haze was calculated. The average value of the haze increase amount of the wafer aiming at 10 ppm is 10.7 ppm, and the average value of the haze increase amount of the wafer aiming at 30 ppm is 31.2 ppm. was made. In addition, the LLS quality was 1 pcs for wafers targeted at 10 ppm and 0 pcs for wafers targeted at 30 ppm, which was good.
このように両面が粗化された狙いＨａｚｅ増加量が１０ｐｐｍと３０ｐｐｍの各１枚について、その表面側に対して取り代５００ｎｍのＣＭＰ加工を行った。ＣＭＰ加工後の各ウェーハのＫＬＡ社製ＳＰ５／１９ｎｍＵｐにてＬＬＳ数を評価したところ、１０ｐｐｍ狙いでは１２ｐｃｓ、３０ｐｐｍ狙いでは９ｐｃｓとなり、後述する比較例の水準１と同等で良好な品質であった。
その後、水中保管した各ウェーハの裏面側をチャックし研磨機のステージにウェーハをアンチャックさせる搬送テストを繰り返し２００回行ったところ、２水準とも２００回ともすべて不良なく搬送することができた。
For each of the wafers with the target haze increments of 10 ppm and 30 ppm, both surfaces of which were roughened in this manner, the front side was subjected to CMP processing with a machining allowance of 500 nm. When the LLS number of each wafer after CMP processing was evaluated by KLA's SP5/19 nmUp, it was 12 pcs when aiming at 10 ppm and 9 pcs when aiming at 30 ppm.
After that, a transfer test was repeated 200 times, in which the back side of each wafer stored in water was chucked and the wafer was unchucked on the stage of the polishing machine.
（実施例２）
次に、図６の本発明の評価方法に基づき、粗化洗浄を安定的に行うための洗浄液中の過酸化水素濃度の評価を行った。
Ｈａｚｅ増加量が１０ｐｐｍとなるように、実施例１のＳ２，Ｓ３の結果を元に、ＮＨ４ＯＨ濃度が０．０３ｗｔ％でＨ２Ｏ２濃度が０．０５ｗｔ％、温度が８０℃の洗浄液の過酸化水素濃度を評価した。
初めにＳ１１の洗浄液濃度調査工程のように、洗浄温度（８０℃）、ＮＨ４ＯＨ濃度（０．０３ｗｔ％）、Ｈ２Ｏ２濃度および粗化量の相関関係を取得した。
具体的には、まず、シリコンウェーハをＮＨ４ＯＨ：Ｈ２Ｏ２：Ｈ２Ｏ＝１：１：１０の洗浄液にて８０℃で３ｍｉｎ洗浄し自然酸化膜が存在するウェーハを作製し（調査用シリコンウェーハ）、ＳＰ３にてＨａｚｅ値を取得した。次に、ＮＨ４ＯＨ濃度が０．０３ｗｔ％、洗浄温度が８０℃の洗浄液でＨ２Ｏ２濃度を変えて自然酸化膜が存在するシリコンウェーハを３ｍｉｎ洗浄した。洗浄後のウェーハのＨａｚｅ値をＳＰ３にて取得し、Ｈａｚｅ増加量を算出した。その結果は図７と同様であった。すなわち、例えばＨ２Ｏ２濃度が０．０５ｗｔ％の場合は４１ｐｐｍ、０．０２ｗｔ％の場合は１８１ｐｐｍとなり、Ｈ２Ｏ２濃度の増加に伴い粗化量（即ちＨａｚｅ増加量）が小さくなる相関関係が得られた。
(Example 2)
Next, based on the evaluation method of the present invention shown in FIG. 6, the concentration of hydrogen peroxide in the cleaning liquid for stably performing roughening cleaning was evaluated.
Based on the results of S2 and S3 in Example 1, a cleaning solution having an NH 4 OH concentration of 0.03 wt%, an H 2 O 2 concentration of 0.05 wt%, and a temperature of 80° C. was used so that the haze increase amount was 10 ppm. was evaluated for hydrogen peroxide concentration.
First, like the cleaning liquid concentration investigation step of S11, the correlation among cleaning temperature (80° C.), NH 4 OH concentration (0.03 wt %), H 2 O 2 concentration and roughening amount was obtained.
Specifically, first, a silicon wafer was washed with a cleaning solution of NH 4 OH:H 2 O 2 :H 2 O=1:1:10 at 80° C. for 3 minutes to prepare a wafer having a natural oxide film (investigation silicon wafer), and the Haze value was obtained at SP3. Next, the silicon wafer having the native oxide film was cleaned for 3 minutes with a cleaning solution having an NH 4 OH concentration of 0.03 wt % and a cleaning temperature of 80° C. while changing the H 2 O 2 concentration. The haze value of the wafer after cleaning was acquired in SP3, and the increase in haze was calculated. The results were similar to those in FIG. That is, for example, when the H 2 O 2 concentration is 0.05 wt%, it is 41 ppm , and when it is 0.02 wt%, it is 181 ppm. relationship was obtained.
次に、Ｓ１２の過酸化水素濃度評価工程を行った。
まず、この洗浄液にてシリコンウェーハを２００枚洗浄し、両面粗化されたシリコンウェーハを製造した。２００枚洗浄後の洗浄液（評価対象洗浄液）中の過酸化水素濃度を評価するため、Ｈａｚｅ値を取得してある自然酸化膜が存在するウェーハを洗浄した後、ＳＰ３にてＨａｚｅ値を取得し、Ｈａｚｅ増加量を算出した。その結果、Ｈａｚｅ増加量は６０ｐｐｍとなった。
図７の相関関係を参照すると、評価対象洗浄液中のＨ２Ｏ２濃度が約０．０４ｗｔ％と求まった。２００枚洗浄前の狙いＨ２Ｏ２濃度が０．０５ｗｔ％であることから、約０．０１ｗｔ％濃度が低下したと判断した。恐らく、２００枚洗浄したことで、ウェーハに薬液が付着したことや、純水（リンス）槽からの持ち込みが原因と考えられる。
Next, the hydrogen peroxide concentration evaluation step of S12 was performed.
First, 200 silicon wafers were washed with this washing liquid to produce silicon wafers having both sides roughened. In order to evaluate the concentration of hydrogen peroxide in the cleaning solution (cleaning solution to be evaluated) after cleaning 200 wafers, the Haze value was acquired. Haze increase amount was calculated. As a result, the haze increase was 60 ppm.
Referring to the correlation in FIG. 7, the H 2 O 2 concentration in the evaluation target cleaning liquid was found to be about 0.04 wt %. Since the target H 2 O 2 concentration before washing 200 sheets was 0.05 wt %, it was determined that the concentration decreased by about 0.01 wt %. The reason is probably that the chemical solution adhered to the wafers after washing 200 wafers, or that the wafers were brought in from a pure water (rinse) tank.
次にＳ１３の過酸化水素濃度管理工程にて、狙いＨ２Ｏ２濃度である０．０５ｗｔ％になるように、Ｈ２Ｏ２を洗浄液に注加した。
その後、確認のため、Ｈａｚｅ値を取得してある自然酸化膜が存在するウェーハを洗浄した後、ＳＰ３にてＨａｚｅ値を取得し、Ｈａｚｅ増加量を算出した。その結果、４０ｐｐｍと求まり、相関関係からＨ２Ｏ２が約０．０５ｗｔ％と求まり、Ｈ２Ｏ２濃度が狙い通りであることを確認できた。
Next, in the hydrogen peroxide concentration control step of S13, H 2 O 2 was added to the cleaning solution so as to achieve a target H 2 O 2 concentration of 0.05 wt %.
After that, for confirmation, after cleaning the wafer having the natural oxide film for which the haze value was obtained, the haze value was obtained in SP3, and the increase in haze was calculated. As a result, it was found to be 40 ppm, and from the correlation it was found that H 2 O 2 was approximately 0.05 wt %, confirming that the H 2 O 2 concentration was as intended.
以上の結果から、本発明の洗浄方法を用いることで、シリコンウェーハの表裏面（特に裏面）を、チャックによる吸着に適した粗さを示すのに十分に粗化することができたことが分かる。さらに本発明の洗浄液中の過酸化水素濃度の評価方法や管理方法を用いることで、従来困難であった微量の過酸化水素濃度を評価でき、また管理できることが分かる。 From the above results, it can be seen that by using the cleaning method of the present invention, the front and back surfaces (especially the back surface) of the silicon wafer could be sufficiently roughened to exhibit roughness suitable for adsorption by the chuck. . Furthermore, by using the method for evaluating and controlling the concentration of hydrogen peroxide in the cleaning solution of the present invention, it is possible to evaluate and manage the minute concentration of hydrogen peroxide, which has been difficult in the past.
（比較例）
ＤＳＰ加工後の自然酸化膜がないベア面のシリコンウェーハを用意し、ＳＰ３にてＨａｚｅ評価を行った。次にバッチ式洗浄機にて、表１に示した６つの水準の条件（液組成、洗浄温度、洗浄時間）にて洗浄を行った。洗浄液の調製には２８質量％のアンモニア水（ＮＨ４ＯＨ）、３０質量％の過酸化水素水（Ｈ２Ｏ２）を用いた。洗浄後のウェーハをＳＰ３で評価し、Ｈａｚｅ値を取得し、Ｈａｚｅ増加量を算出した。
(Comparative example)
A silicon wafer having a bare surface without a natural oxide film after DSP processing was prepared, and haze evaluation was performed in SP3. Next, using a batch-type washing machine, washing was carried out under six levels of conditions (liquid composition, washing temperature, washing time) shown in Table 1. 28% by mass of ammonia water (NH 4 OH) and 30% by mass of hydrogen peroxide solution (H 2 O 2 ) were used to prepare the cleaning liquid. The wafer after cleaning was evaluated by SP3, the haze value was obtained, and the increase in haze was calculated.
表１の全水準ともＨａｚｅ増加量は１ｐｐｍ以下となり、実施例１の１０ｐｐｍや３０ｐｐｍと比較すると小さいことから粗化されていないと判断した。
水準１及び水準５のウェーハに対し、取り代５００ｎｍのＣＭＰ加工を行った後、ＳＰ５／１９ｎｍＵＰにてＬＬＳ数を評価したところ、水準１では１０ｐｃｓ、水準５では３４２ｐｃｓとなった。水準１のＬＬＳレベルは実施例１と同等であったが、水準５は粗化洗浄工程時にエッチング優勢となり形成されたエッチピットがＣＭＰ工程で残留したためＬＬＳ品質が悪化したと考えられる。次に水準１と水準５のウェーハに対し、実施例１と同様のチャックテストを２００回行った。ウェーハがチャックから脱離しない不良が水準１は４回、水準５では３回発生した。
また水準５の洗浄液のＨ２Ｏ２濃度を吸光度方式の濃度計で計測したが、検出下限値以下となり評価することができなかった。
All the levels in Table 1 showed an increase in haze of 1 ppm or less, which was smaller than the values of 10 ppm and 30 ppm in Example 1. Therefore, it was judged that the surface was not roughened.
After performing CMP processing with a machining allowance of 500 nm on the wafers of
The H 2 O 2 concentration of the
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。 It should be noted that the present invention is not limited to the above embodiments. The above embodiment is an example, and any device that has substantially the same configuration as the technical idea described in the claims of the present invention and produces similar effects is the present invention. It is included in the technical scope of the invention.
Claims (8)
自然酸化膜がないベア面が露出した調査用シリコンウェーハを、水酸化アンモニウムを含み、かつ、過酸化水素濃度が０～０．１５ｗｔ％の水溶液である洗浄液で洗浄することで粗化された前記調査用シリコンウェーハの表裏面又は裏面の粗化量と、
前記洗浄液の温度と、
前記洗浄液中の水酸化アンモニウム濃度と、
前記洗浄液中の過酸化水素濃度との相関関係を予め取得しておく洗浄液濃度調査工程と、
該洗浄液濃度調査工程で取得しておいた前記相関関係に基づいて、所望の粗化量から、前記洗浄液の温度、前記洗浄液中の水酸化アンモニウム濃度及び過酸化水素濃度の粗化洗浄条件を決定する粗化洗浄条件決定工程と、
該粗化洗浄条件決定工程で決定した粗化洗浄条件で、自然酸化膜がないベア面が露出した粗化対象シリコンウェーハを洗浄することで、該粗化対象シリコンウェーハの表裏面又は裏面を粗化する粗化洗浄工程とを有することを特徴とするシリコンウェーハの洗浄方法。 A cleaning method for roughening a silicon wafer, comprising:
The silicon wafer for investigation, in which the bare surface without a natural oxide film is exposed, is roughened by washing with a cleaning liquid that is an aqueous solution containing ammonium hydroxide and having a hydrogen peroxide concentration of 0 to 0.15 wt%. The amount of roughening on the front and back surfaces or the back surface of the silicon wafer for investigation,
the temperature of the cleaning liquid;
ammonium hydroxide concentration in the cleaning solution;
a cleaning solution concentration investigation step of obtaining in advance a correlation with the concentration of hydrogen peroxide in the cleaning solution;
Based on the correlation obtained in the cleaning liquid concentration investigation step, roughening cleaning conditions such as the temperature of the cleaning liquid, the ammonium hydroxide concentration, and the hydrogen peroxide concentration in the cleaning liquid are determined from the desired amount of roughening. a roughening cleaning condition determining step;
The front and rear surfaces or the rear surface of the silicon wafer to be roughened is roughened by washing the silicon wafer to be roughened, the bare surface of which is free of the natural oxide film, exposed under the roughening washing condition determined in the roughening washing condition determining step. A method for cleaning a silicon wafer, characterized by comprising a roughening cleaning step.
前記調査用シリコンウェーハの前記洗浄前後にパーティクルカウンターにてＨａｚｅ値を取得し、前記洗浄後のＨａｚｅ値の増加量を前記粗化量とすることを特徴とする請求項１に記載のシリコンウェーハの洗浄方法。 In the cleaning liquid concentration investigation step,
2. The silicon wafer according to claim 1, wherein a haze value is obtained with a particle counter before and after the cleaning of the silicon wafer for investigation, and an increase in the haze value after the cleaning is used as the roughening amount. cleaning method.
前記過酸化水素濃度が、該過酸化水素濃度の変動に対する前記粗化量の変動が所定値以下の濃度範囲内であり、かつ、前記粗化洗浄工程における前記洗浄後の粗化対象シリコンウェーハ表面に、該洗浄中に形成された自然酸化膜が残るように、
前記粗化洗浄条件を決定することを特徴とする請求項１または請求項２に記載のシリコンウェーハの洗浄方法。 When determining the roughening cleaning conditions in the roughening cleaning condition determination step,
The hydrogen peroxide concentration is within a concentration range in which the variation in the amount of roughening with respect to the variation in the hydrogen peroxide concentration is a predetermined value or less, and the surface of the silicon wafer to be roughened after the cleaning in the roughening cleaning step. In addition, so that the native oxide film formed during the cleaning remains,
3. The method of cleaning a silicon wafer according to claim 1, wherein said roughening cleaning condition is determined.
自然酸化膜を有する調査用シリコンウェーハを、水酸化アンモニウムを含み、かつ、過酸化水素濃度が０～０．１５ｗｔ％の水溶液である洗浄液で洗浄することで粗化された前記調査用シリコンウェーハの表裏面又は裏面の粗化量と、
前記洗浄液の温度と、
前記洗浄液中の水酸化アンモニウム濃度と、
前記洗浄液中の過酸化水素濃度との相関関係を予め取得しておく洗浄液濃度調査工程と、
該洗浄液濃度調査工程で取得しておいた前記相関関係に基づいて、
自然酸化膜を有するシリコンウェーハを、少なくとも水酸化アンモニウムを含む水溶液である評価対象洗浄液で洗浄することで粗化された前記シリコンウェーハの表裏面又は裏面の粗化量と、
前記評価対象洗浄液の温度と、
前記評価対象洗浄液中の水酸化アンモニウム濃度とから、
前記評価対象洗浄液中の過酸化水素濃度を評価する過酸化水素濃度評価工程とを有することを特徴とする洗浄液中の過酸化水素濃度評価方法。 A method for evaluating the concentration of hydrogen peroxide in a cleaning liquid, comprising:
A silicon wafer for investigation having a natural oxide film was roughened by cleaning the silicon wafer for investigation with a cleaning liquid that is an aqueous solution containing ammonium hydroxide and having a hydrogen peroxide concentration of 0 to 0.15 wt%. The amount of roughening on the front and back surfaces or the back surface,
the temperature of the cleaning liquid;
ammonium hydroxide concentration in the cleaning solution;
a cleaning solution concentration investigation step of obtaining in advance a correlation with the concentration of hydrogen peroxide in the cleaning solution;
Based on the correlation obtained in the cleaning solution concentration investigation step,
A roughening amount of the front and back surfaces or the back surface of the silicon wafer roughened by cleaning the silicon wafer having a natural oxide film with an evaluation target cleaning liquid that is an aqueous solution containing at least ammonium hydroxide;
the temperature of the cleaning liquid to be evaluated;
From the concentration of ammonium hydroxide in the cleaning liquid to be evaluated,
and a hydrogen peroxide concentration evaluation step of evaluating the concentration of hydrogen peroxide in the cleaning liquid to be evaluated.
請求項７に記載の洗浄液中の過酸化水素濃度評価方法により、前記評価対象洗浄液中の過酸化水素濃度を評価し、
該評価結果に基づき、評価後の洗浄液中の過酸化水素濃度を調整することを特徴とする洗浄液中の過酸化水素濃度管理方法。 A method for controlling the concentration of hydrogen peroxide in a cleaning liquid, comprising:
Evaluating the concentration of hydrogen peroxide in the cleaning liquid to be evaluated by the method for evaluating the concentration of hydrogen peroxide in the cleaning liquid according to claim 7,
A method for controlling the concentration of hydrogen peroxide in a cleaning solution, comprising adjusting the concentration of hydrogen peroxide in the cleaning solution after evaluation based on the evaluation result.
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| KR1020247006740A KR20240051142A (en) | 2021-09-06 | 2022-07-20 | Silicon wafer cleaning and manufacturing methods, hydrogen peroxide concentration evaluation method in cleaning solution, and hydrogen peroxide concentration management method |
| PCT/JP2022/028175 WO2023032497A1 (en) | 2021-09-06 | 2022-07-20 | Silicon wafer cleaning method and production method, method for evaluating concentration of hydrogen peroxide in cleaning fluid, and method for managing hydrogen peroxide concentration in cleaning fluid |
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