JPH11162953A - Etching of silicon wafer - Google Patents
Etching of silicon waferInfo
- Publication number
- JPH11162953A JPH11162953A JP24526498A JP24526498A JPH11162953A JP H11162953 A JPH11162953 A JP H11162953A JP 24526498 A JP24526498 A JP 24526498A JP 24526498 A JP24526498 A JP 24526498A JP H11162953 A JPH11162953 A JP H11162953A
- Authority
- JP
- Japan
- Prior art keywords
- etching
- solution
- aqueous solution
- prepared
- 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.)
- Granted
Links
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 33
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 32
- 239000010703 silicon Substances 0.000 title claims abstract description 32
- 238000005530 etching Methods 0.000 title claims description 170
- 239000000243 solution Substances 0.000 claims abstract description 71
- KWYUFKZDYYNOTN-UHFFFAOYSA-M potassium hydroxide Substances [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims abstract description 64
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 36
- 239000007864 aqueous solution Substances 0.000 claims abstract description 32
- 239000003513 alkali Substances 0.000 claims abstract description 20
- 150000003839 salts Chemical class 0.000 claims abstract description 12
- 239000002280 amphoteric surfactant Substances 0.000 claims abstract description 10
- 229910052802 copper Inorganic materials 0.000 claims abstract description 10
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 10
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 claims abstract description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims abstract description 3
- 229910002651 NO3 Inorganic materials 0.000 claims abstract description 3
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims abstract description 3
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims abstract description 3
- 239000000203 mixture Substances 0.000 claims description 23
- 238000000034 method Methods 0.000 claims description 21
- 229910052751 metal Inorganic materials 0.000 claims description 19
- 239000002184 metal Substances 0.000 claims description 19
- 239000002253 acid Substances 0.000 claims description 18
- 239000003945 anionic surfactant Substances 0.000 claims description 10
- 239000003093 cationic surfactant Substances 0.000 claims description 10
- 229910021645 metal ion Inorganic materials 0.000 claims description 10
- 229920000620 organic polymer Polymers 0.000 claims description 10
- 239000011734 sodium Substances 0.000 claims description 9
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical group C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 7
- 229910052708 sodium Inorganic materials 0.000 claims description 7
- 229920000642 polymer Polymers 0.000 claims description 6
- DDXLVDQZPFLQMZ-UHFFFAOYSA-M dodecyl(trimethyl)azanium;chloride Chemical group [Cl-].CCCCCCCCCCCC[N+](C)(C)C DDXLVDQZPFLQMZ-UHFFFAOYSA-M 0.000 claims description 5
- 229940094506 lauryl betaine Drugs 0.000 claims description 5
- DVEKCXOJTLDBFE-UHFFFAOYSA-N n-dodecyl-n,n-dimethylglycinate Chemical group CCCCCCCCCCCC[N+](C)(C)CC([O-])=O DVEKCXOJTLDBFE-UHFFFAOYSA-N 0.000 claims description 5
- 229910052700 potassium Inorganic materials 0.000 claims description 4
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims description 2
- VBIIFPGSPJYLRR-UHFFFAOYSA-M Stearyltrimethylammonium chloride Chemical compound [Cl-].CCCCCCCCCCCCCCCCCC[N+](C)(C)C VBIIFPGSPJYLRR-UHFFFAOYSA-M 0.000 claims description 2
- 239000012670 alkaline solution Substances 0.000 claims description 2
- UPHWVVKYDQHTCF-UHFFFAOYSA-N octadecylazanium;acetate Chemical compound CC(O)=O.CCCCCCCCCCCCCCCCCCN UPHWVVKYDQHTCF-UHFFFAOYSA-N 0.000 claims description 2
- 239000011591 potassium Substances 0.000 claims description 2
- HVYJSOSGTDINLW-UHFFFAOYSA-N 2-[dimethyl(octadecyl)azaniumyl]acetate Chemical compound CCCCCCCCCCCCCCCCCC[N+](C)(C)CC([O-])=O HVYJSOSGTDINLW-UHFFFAOYSA-N 0.000 claims 1
- SYELZBGXAIXKHU-UHFFFAOYSA-N dodecyldimethylamine N-oxide Chemical compound CCCCCCCCCCCC[N+](C)(C)[O-] SYELZBGXAIXKHU-UHFFFAOYSA-N 0.000 claims 1
- 230000003746 surface roughness Effects 0.000 abstract description 13
- 239000004094 surface-active agent Substances 0.000 abstract description 9
- 125000000129 anionic group Chemical group 0.000 abstract 1
- 150000001768 cations Chemical class 0.000 abstract 1
- 235000012431 wafers Nutrition 0.000 description 77
- 238000004140 cleaning Methods 0.000 description 54
- 230000000052 comparative effect Effects 0.000 description 18
- 238000001035 drying Methods 0.000 description 16
- 239000007788 liquid Substances 0.000 description 10
- 239000013078 crystal Substances 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 7
- 150000002500 ions Chemical class 0.000 description 7
- 229910052760 oxygen Inorganic materials 0.000 description 7
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 6
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 5
- 229910052742 iron Inorganic materials 0.000 description 5
- 238000005498 polishing Methods 0.000 description 5
- 229910021529 ammonia Inorganic materials 0.000 description 4
- -1 ammonia peroxide Chemical class 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- 125000000217 alkyl group Chemical group 0.000 description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 description 2
- 238000003486 chemical etching Methods 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 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 2
- PSZYNBSKGUBXEH-UHFFFAOYSA-M naphthalene-1-sulfonate Chemical compound C1=CC=C2C(S(=O)(=O)[O-])=CC=CC2=C1 PSZYNBSKGUBXEH-UHFFFAOYSA-M 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 239000006061 abrasive grain Substances 0.000 description 1
- 239000012190 activator Substances 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 238000001479 atomic absorption spectroscopy Methods 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 238000010835 comparative analysis Methods 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 125000000896 monocarboxylic acid group Chemical group 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000006557 surface reaction Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Mechanical Treatment Of Semiconductor (AREA)
- Weting (AREA)
Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明はシリコンウェーハの
マクロな形状精度である平坦度とミクロな形状精度であ
る表面粗さの双方を良好にする化学エッチング方法に関
する。更に詳しくはシリコン単結晶インゴットを切断し
て得た薄円板をラッピングして洗浄した後のシリコンウ
ェーハをエッチングするのに適した方法に関するもので
ある。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemical etching method for improving both flatness, which is a macro shape accuracy, and surface roughness, which is a micro shape accuracy, of a silicon wafer. More specifically, the present invention relates to a method suitable for etching a silicon wafer after lapping and cleaning a thin disk obtained by cutting a silicon single crystal ingot.
【0002】[0002]
【従来の技術】シリコンウェーハはシリコン単結晶イン
ゴットを引上げ、そのインゴットを切断して得た薄円板
をラッピング、エッチング、ポリッシングの順に加工さ
れる。近年、デバイスの集積度が向上するにつれて、超
LSI用ウェーハに極めて高い形状精度が要求されてい
る。従来、図2に示すようにラッピングしたシリコンウ
ェーハはラッピング後洗浄が行われ、次いでエッチング
前洗浄、エッチング、エッチング後洗浄が行われた後、
酸素ドナー消去のための熱処理が行われる。ここで、ラ
ッピング後洗浄はラッピングパウダ、ラッピングスラリ
ー等を除去することを目的とする。ラッピング後洗浄で
は界面活性剤を添加したアルカリ性洗浄液又はアンモニ
ア過水を主要成分とする洗浄液が用いられ、5槽の洗浄
槽に順次シリコンウェーハを浸漬して洗浄している。ま
たエッチング前洗浄は有機物及びラッピング後の残留物
を取り除くことを目的とする。ここではアルカリ水溶液
を主要成分とする洗浄液が用いられ、7槽の洗浄槽に順
次シリコンウェーハを浸漬して洗浄している。更にエッ
チング後洗浄は酸素ドナー消去の前洗浄の意味もあり、
清浄度が必要とされ、そのためアンモニア過水を主要成
分とする洗浄液が用いられ、8槽の洗浄槽に順次シリコ
ンウェーハを浸漬して洗浄している。2. Description of the Related Art A silicon wafer is processed by pulling up a silicon single crystal ingot, lapping a thin disk obtained by cutting the ingot, etching and polishing. In recent years, as the degree of integration of devices has increased, extremely high shape accuracy has been required for VLSI wafers. Conventionally, as shown in FIG. 2, the wrapped silicon wafer is subjected to cleaning after lapping, followed by pre-etching cleaning, etching, and post-etching cleaning.
A heat treatment for erasing oxygen donors is performed. Here, the cleaning after lapping aims at removing lapping powder, lapping slurry and the like. In the cleaning after lapping, an alkaline cleaning liquid to which a surfactant is added or a cleaning liquid containing ammonia peroxide as a main component is used, and silicon wafers are sequentially immersed in five cleaning tanks for cleaning. The pre-etch cleaning aims at removing organic substances and residues after lapping. Here, a cleaning liquid containing an alkaline aqueous solution as a main component is used, and silicon wafers are sequentially immersed in seven cleaning tanks for cleaning. Furthermore, post-etch cleaning also has the meaning of cleaning before oxygen donor erasure,
Cleanliness is required. Therefore, a cleaning liquid containing ammonia peroxide as a main component is used, and silicon wafers are sequentially immersed in eight cleaning tanks for cleaning.
【0003】エッチングには、酸エッチング又はアルカ
リエッチングのいずれかの方法が採られる。このエッチ
ング工程では、1〜2槽からなるエッチング槽を用い
て、ラッピング工程で両面を同時に研磨することにより
平坦度、板厚ともに精度高く加工したシリコンウェーハ
に対して、残留砥粒と加工変質層を除く目的で、ウェー
ハ表面を20〜50μm程度化学的に除去している。酸
エッチングは、シリコンウェーハに対して選択エッチン
グ性がなく、表面粗さが小さいためミクロな形状精度が
向上し、かつエッチング能率の高い利点がある。この酸
エッチングのエッチング液には、フッ酸(HF)と硝酸
(HNO3)の混酸を水(H2O)或いは酢酸(CH3C
OOH)で希釈した3成分素によるエッチング液が主と
して用いられている。酸エッチングで上記利点が得られ
るのは、上記エッチング液により拡散律速の条件に基づ
いてエッチングが進行し、この拡散律速の条件下では、
結晶表面の面方位、結晶欠陥等に反応速度は依存せず、
結晶表面における拡散が主たる効果を持つためと考えら
れている。一方、アルカリエッチングは、平坦度に優れ
マクロな形状精度が向上し、かつ金属汚染が少なく、酸
エッチングにおけるNOxのような有害副産物の問題や
取扱い上の危険性もない特長がある。このアルカリエッ
チングのエッチング液には、KOHやNaOHが用いら
れている。アルカリエッチングで上記特長が得られるの
は、このエッチングが基本的に表面反応律速の条件に基
づいて進行するためであると考えられている。[0003] Either acid etching or alkali etching is used for etching. In this etching step, a silicon wafer processed with high precision in both flatness and plate thickness by simultaneously polishing both surfaces in a lapping step using an etching tank composed of one or two tanks is used. For the purpose of removing, the surface of the wafer is chemically removed by about 20 to 50 μm. Acid etching has the advantages of not having a selective etching property with respect to a silicon wafer and having a small surface roughness, thereby improving micro-shape accuracy and high etching efficiency. An etching solution for this acid etching is a mixture of hydrofluoric acid (HF) and nitric acid (HNO 3 ) in water (H 2 O) or acetic acid (CH 3 C).
An etchant based on a ternary element diluted with OOH) is mainly used. The advantage obtained by the acid etching is that the etching proceeds by the etching solution under the condition of diffusion control, and under the condition of diffusion control,
The reaction rate does not depend on the plane orientation of the crystal surface, crystal defects, etc.,
It is believed that diffusion at the crystal surface has a major effect. On the other hand, the alkali etching has features that the flatness is excellent, the macro shape accuracy is improved, the metal contamination is small, and there is no problem of harmful by-products such as NOx in acid etching and there is no danger in handling. KOH or NaOH is used as an etchant for this alkali etching. It is considered that the above characteristics are obtained by the alkali etching because the etching basically proceeds based on the condition of the surface reaction.
【0004】[0004]
【発明が解決しようとする課題】しかしながら、酸エッ
チングにしても、アルカリエッチングにしても上記組成
のエッチング液を用いた場合、ウェーハの形状精度の制
御が非常に難しい問題点があった。即ち、酸エッチング
はシリコンウェーハの表面粗さを良好にする反面、酸エ
ッチングが進行するにつれ、ウェーハ外周部がだれて、
マクロな形状精度である平坦度が損なわれ、薬液のコス
トが高く、しかもエッチング液の組成を制御しかつ維持
することが困難な欠点があった。However, in the case of using an etching solution having the above-mentioned composition in both the acid etching and the alkali etching, there is a problem that it is very difficult to control the shape accuracy of the wafer. That is, while acid etching improves the surface roughness of the silicon wafer, as the acid etching progresses, the outer peripheral portion of the wafer sags,
The flatness, which is a macro shape accuracy, is impaired, the cost of the chemical solution is high, and it is difficult to control and maintain the composition of the etching solution.
【0005】また、アルカリエッチングは、シリコンウ
ェーハの平坦度を良好にする反面、異方性エッチングで
あるため、ミクロな形状精度である表面粗さに劣る不具
合があった。このアルカリエッチングは上述したように
反応律速であり、エッチング速度はシリコンウェーハの
結晶面方位に強く依存し、次の式(1)の特性があり、[0005] Although the alkali etching improves the flatness of the silicon wafer, it is anisotropic etching, and thus has a disadvantage that the surface roughness, which is a microscopic shape accuracy, is inferior. As described above, this alkali etching is reaction-limited, and the etching rate strongly depends on the crystal plane orientation of the silicon wafer, and has the following formula (1).
【0006】[0006]
【数1】 (Equation 1)
【0007】このため、特に{100}ウェーハをアル
カリエッチングすると、ミクロな形状精度である表面粗
さが悪化していた。更に、従来のラッピングからエッチ
ング後洗浄まで、20有余の洗浄槽及びエッチング槽が
配置されるため、取扱いが複雑になる上、薬液量、設
備、時間、操作員等を多く要し、比較的エッチングコス
トが高くなる問題点もあった。本発明の目的は、マクロ
な形状精度である平坦度とミクロな形状精度である表面
粗さの双方を良好にするシリコンウェーハの化学エッチ
ング方法を提供することにある。[0007] For this reason, in particular, when the {100} wafer is alkali-etched, the surface roughness, which is a microscopic shape accuracy, has deteriorated. In addition, since there are more than 20 cleaning tanks and etching tanks from conventional lapping to post-etch cleaning, handling becomes complicated and requires a large amount of chemicals, equipment, time, operators, etc., and relatively etching is required. There was also a problem that the cost became high. An object of the present invention is to provide a method for chemically etching a silicon wafer, which can improve both flatness, which is a macro shape accuracy, and surface roughness, which is a micro shape accuracy.
【0008】[0008]
【課題を解決するための手段】請求項1に係る発明は、
アルカリ水溶液に金属塩、アニオン界面活性剤、カチオ
ン界面活性剤、両性界面活性剤又は極性基を有する有機
高分子を添加して調製されたエッチング液を20〜60
℃の温度にした後、このエッチング液にシリコンウェー
ハを浸漬してエッチングすることを特徴とするシリコン
ウェーハのエッチング方法である。金属塩、アニオン界
面活性剤、カチオン界面活性剤、両性界面活性剤又は極
性基を有する有機高分子を含まないエッチング液にシリ
コンウェーハを浸漬した場合には、ラッピング後のダメ
ージ及び粗さによって、このウェーハの表面電位は不均
一になると推察される。しかし、本発明の金属塩、アニ
オン界面活性剤、カチオン界面活性剤、両性界面活性剤
又は極性基を有する有機高分子を含んだアルカリ水溶液
でエッチングすると、エッチング液中で金属塩の金属イ
オン、界面活性剤又は有機高分子の極性基がマイナス電
位のウェーハ表面に付着するため、ウェーハの表面電位
は均一化する。これは付着による表面電位の均一化とエ
ッチング反応とが平衡状態を作り出し、見かけ上、表面
電位の分布を均一にしたエッチングサイクルを実現した
ものと考えられる。この状態でエッチングが進行する
と、ウェーハ表面は均一にエッチングされ、ウェーハの
ミクロな形状精度である表面粗さを劣化させない。この
エッチングはアルカリエッチングであるため、反応律速
で行われ、ウェーハのマクロな形状精度である平坦度を
良好にする。なお、本明細書で「平坦度」とはシリコン
ウェーハのマクロな形状精度であって、「平坦度が良好
である」とはウェーハの厚み分布が均一であることを意
味し、「表面粗さ」とはシリコンウェーハのミクロな形
状精度であって、「平坦度が良好である」とはウェーハ
の表面のラフネスアベレージ(Roughness average: R
a)が小さいことを意味する。The invention according to claim 1 is
An etching solution prepared by adding a metal salt, an anionic surfactant, a cationic surfactant, an amphoteric surfactant or an organic polymer having a polar group to an aqueous alkali solution is used for 20 to 60 times.
This is a method of etching a silicon wafer, wherein the silicon wafer is immersed in the etching solution and then etched after the temperature is set to a temperature of ° C. When a silicon wafer is immersed in an etching solution that does not contain a metal salt, an anionic surfactant, a cationic surfactant, an amphoteric surfactant or an organic polymer having a polar group, the damage and roughness after lapping cause It is assumed that the surface potential of the wafer becomes non-uniform. However, when etching with an alkali aqueous solution containing the metal salt of the present invention, an anionic surfactant, a cationic surfactant, an amphoteric surfactant or an organic polymer having a polar group, the metal ion of the metal salt, the interface Since the activator or the polar group of the organic polymer adheres to the wafer surface having a negative potential, the surface potential of the wafer becomes uniform. This is presumably because the uniformization of the surface potential due to adhesion and the etching reaction created an equilibrium state, and an etching cycle in which the distribution of the surface potential was apparently uniform was realized. When etching proceeds in this state, the wafer surface is uniformly etched, and does not deteriorate the surface roughness, which is the microscopic shape accuracy of the wafer. Since this etching is alkali etching, the etching is performed at a reaction-determining rate, and the flatness, which is a macro shape accuracy of the wafer, is improved. In this specification, “flatness” is the macro shape accuracy of a silicon wafer, and “good flatness” means that the thickness distribution of the wafer is uniform, and “surface roughness” "Is the microscopic shape accuracy of the silicon wafer, and" good flatness "is the roughness average (Roughness average: R) of the surface of the wafer.
a) means small.
【0009】[0009]
【発明の実施の形態】本発明のシリコンウェーハの化学
エッチングは、ウェーハの平坦度と表面粗さの双方を良
好にする必要があるときに行われる。例えばシリコン単
結晶インゴットを切断して得た薄円板をラッピング(機
械研磨)した後で、又はシリコンウェーハを酸素ドナー
消去熱処理してポリッシング(機械的化学的研磨)した
後で、或いは仕上った後で、行われる。好ましくはラッ
ピング後に行われる。本発明のエッチング液は、アルカ
リ水溶液に金属塩、アニオン界面活性剤、カチオン界面
活性剤、両性界面活性剤又は極性基を有する有機高分子
を添加して調製される。アルカリ水溶液としてはNH4
OH水溶液、NaOH水溶液、KOH水溶液又はエチレ
ンジアミン水溶液が挙げられる。このときNH4OH水
溶液、NaOH水溶液、KOH水溶液又はエチレンジア
ミン水溶液は容積比でNH4OH/H2O=0.01〜
1.0、重量比でNaOH/H2O=0.2〜0.5、
重量比でKOH/H2O=0.2〜0.5又は重量比で
H2NCH2CH2NH2/H2O=0.2〜0.5の組成
を有する。NH4OH(アンモニア水)の濃度は20〜
40%の中から選択され、特に市販されている29%濃
度のNH4OHが容易に入手できるため好ましい。Na
OH(水酸化ナトリウム液)の濃度は10〜60%の中
から選択され、特に市販されている48%濃度のNaO
Hが容易に入手できるため好ましい。またKOH(水酸
化カリウム液)の濃度は10〜60%の中から選択さ
れ、特に市販されている48%濃度のKOHが容易に入
手できるため好ましい。更にH2NCH2CH2NH2(エ
チレンジアミン液)の濃度は10〜50%の中から選択
され、特に市販されている40%濃度のH2NCH2CH
2NH2が容易に入手できるため好ましい。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Chemical etching of a silicon wafer according to the present invention is performed when it is necessary to improve both the flatness and the surface roughness of the wafer. For example, after lapping (mechanical polishing) of a thin disk obtained by cutting a silicon single crystal ingot, or after polishing (mechanical chemical polishing) by performing an oxygen donor erasure heat treatment, or after finishing In, it is done. Preferably, it is performed after lapping. The etching solution of the present invention is prepared by adding a metal salt, an anionic surfactant, a cationic surfactant, an amphoteric surfactant or an organic polymer having a polar group to an aqueous alkali solution. NH 4 as the alkaline aqueous solution
An OH aqueous solution, an NaOH aqueous solution, a KOH aqueous solution, or an ethylenediamine aqueous solution can be used. At this time, the aqueous solution of NH 4 OH, the aqueous solution of NaOH, the aqueous solution of KOH, or the aqueous solution of ethylenediamine has a volume ratio of NH 4 OH / H 2 O = 0.01 to
1.0, NaOH in a weight ratio / H 2 O = 0.2~0.5,
Having a composition of H 2 NCH 2 CH 2 NH 2 / H 2 O = 0.2~0.5 with KOH / H 2 O = 0.2~0.5 or weight by weight. The concentration of NH 4 OH (ammonia water) is 20 ~
NH 4 OH, which is selected from among 40% and is particularly preferably commercially available at a concentration of 29%, is preferred. Na
The concentration of OH (sodium hydroxide solution) is selected from 10 to 60%, and particularly, commercially available 48% concentration NaO
H is preferred because it is readily available. The concentration of KOH (potassium hydroxide solution) is selected from 10% to 60%, and particularly preferred is a commercially available 48% concentration KOH which can be easily obtained. Further, the concentration of H 2 NCH 2 CH 2 NH 2 (ethylenediamine solution) is selected from 10 to 50%, and particularly, a commercially available 40% concentration of H 2 NCH 2 CH 2 is used.
2 NH 2 is preferred because it is readily available.
【0010】NH4OH/H2O、NaOH/H2O、K
OH/H2O又はH2NCH2CH2NH2/H2Oを容積比
又は重量比で規定するのは、エッチングの特性を決定す
る第1の因子であり、主にエッチング速度、ウェーハの
表面状態等を決定するためである。ここでNH4OH/
H2Oの容積比が0.01未満、NaOH/H2O又はK
OH/H2Oの重量比がO.2未満、H2NCH2CH2N
H2/H2Oの重量比が0.2未満では、本来のアルカリ
エッチングが行わず、所望のエッチング量が得られな
い。またNH4OH/H2Oの容積比が1.0を超える
か、又はNaOH/H2O又はKOH/H2Oの重量比が
0.5を超えるか、或いはH2NCH2CH2NH2/H2
Oの重量比が0.5を超えると、エッチング過多とな
り、ウェーハの表面が荒れる。好ましい割合はNH4O
H/H2O=0.05〜0.5(容積比)、NaOH/
H2O=0.25〜0.35(重量比)、KOH/H2O
=0.25〜0.35(重量比)又はH2NCH2CH2
NH2/H2O=0.25〜0.35(重量比)である。
アルカリ水溶液に添加する金属塩としては、Cu,Ni
又はFeの硝酸塩、硫酸塩又は塩化物が挙げられる。具
体的には、Cu(NO3)2、CuSO4、Ni(NO3)2、
FeCl2等が例示される。この場合、エッチング液は
アルカリ水溶液がNH4OH水溶液であるときには0.
01〜1.0ppm、好ましくは0.05〜0.2pp
mのCu,Ni又はFeの金属イオンを含んで調製され
る。またアルカリ水溶液がNaOH水溶液又はKOH水
溶液であるときには0.2〜0.5ppm、好ましくは
0.3〜0.4ppmのCu,Ni又はFeの金属イオ
ンを含んで調製される。更にアルカリ水溶液がH2NC
H2CH2NH2水溶液であるときには0.2〜0.5p
pm、好ましくは0.3〜0.4ppmのCu,Ni又
はFeの金属イオンを含んで調製される。NH 4 OH / H 2 O, NaOH / H 2 O, K
Defining OH / H 2 O or H 2 NCH 2 CH 2 NH 2 / H 2 O by volume ratio or weight ratio is the first factor that determines the characteristics of etching, and mainly includes etching rate, wafer This is for determining the surface state and the like. Where NH 4 OH /
H 2 O volume ratio less than 0.01, NaOH / H 2 O or K
When the weight ratio of OH / H 2 O is O.O. Less than 2, H 2 NCH 2 CH 2 N
If the weight ratio of H 2 / H 2 O is less than 0.2, the original alkali etching is not performed, and a desired etching amount cannot be obtained. Also, the volume ratio of NH 4 OH / H 2 O exceeds 1.0, or the weight ratio of NaOH / H 2 O or KOH / H 2 O exceeds 0.5, or H 2 NCH 2 CH 2 NH 2 / H 2
If the weight ratio of O exceeds 0.5, the etching becomes excessive and the surface of the wafer becomes rough. The preferred ratio is NH 4 O
H / H 2 O = 0.05-0.5 (volume ratio), NaOH /
H 2 O = 0.25 to 0.35 (weight ratio), KOH / H 2 O
= 0.25-0.35 (weight ratio) or H 2 NCH 2 CH 2
It is NH 2 / H 2 O = 0.25~0.35 ( weight ratio).
Examples of the metal salt to be added to the alkaline aqueous solution include Cu, Ni
Alternatively, a nitrate, a sulfate or a chloride of Fe may be used. Specifically, Cu (NO 3 ) 2 , CuSO 4 , Ni (NO 3 ) 2 ,
FeCl 2 is exemplified. In this case, when the alkaline aqueous solution is an NH 4 OH aqueous solution, the etching solution is 0.1 mL.
01-1.0 ppm, preferably 0.05-0.2 pp
It is prepared containing m of Cu, Ni or Fe metal ions. When the alkaline aqueous solution is a NaOH aqueous solution or a KOH aqueous solution, it is prepared to contain 0.2 to 0.5 ppm, preferably 0.3 to 0.4 ppm of metal ions of Cu, Ni or Fe. Further, the aqueous alkali solution is H 2 NC
0.2 to 0.5 p when H 2 CH 2 NH 2 aqueous solution
pm, preferably containing 0.3 to 0.4 ppm of metal ions of Cu, Ni or Fe.
【0011】アルカリ水溶液に添加する界面活性剤とし
ては、アニオン界面活性剤、カチオン界面活性剤又は両
性界面活性剤がある。これらの界面活性剤を上記アルカ
リ水溶液に0.1〜2.0重量%、好ましくは0.2〜
1.0重量%添加することによりエッチング液が調製さ
れる。アニオン界面活性剤としてはアルキルナフタレン
スルホン酸ナトリウム、アルキルジフェニルエーテルジ
スルホン酸ナトリウム、アルキルリン酸カリウムが、カ
チオン界面活性剤としてはラウリルトリメチルアンモニ
ウムクロライド、ステアリルトリメチルアンモニウムク
ロライド、ステアリルアミンアセテートが、また両性界
面活性剤としてはラウリルベタインが挙げられる。更に
極性基を有する有機高分子としてはポリスルホン酸型高
分子、ポリカルボン酸型高分子、ポリスルホン酸型高分
子が挙げられる。金属塩、界面活性剤などの添加物の濃
度が上記下限値未満ではウェーハの表面電位を均一化す
るまでには至らず、上記上限値を超えるとエッチング後
にウェーハ表面に残留する金属塩、界面活性剤などの量
が多くなり過ぎ、洗浄して除去することが困難になる。
このように調製されたエッチング液は、エッチング時に
は20〜60℃に維持される。20℃未満ではエッチン
グ速度が極めて遅くなり、60℃を超えるとウェーハの
面粗さが増大する。この温度は好ましくは30〜50℃
である。エッチング時間は全エッチング量が20〜50
μm程度になるように決められる。このエッチング量は
残留砥粒の多寡及び加工変質層の厚さによる。The surfactant to be added to the aqueous alkali solution includes an anionic surfactant, a cationic surfactant or an amphoteric surfactant. 0.1 to 2.0% by weight, preferably 0.2 to 2.0% by weight of these surfactants in the aqueous alkali solution.
An etchant is prepared by adding 1.0% by weight. Examples of anionic surfactants include sodium alkylnaphthalenesulfonate, sodium alkyldiphenyletherdisulfonate, and potassium alkylphosphate, and examples of the cationic surfactant include lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, and stearylamine acetate. Examples include lauryl betaine. Further, examples of the organic polymer having a polar group include a polysulfonic acid type polymer, a polycarboxylic acid type polymer, and a polysulfonic acid type polymer. If the concentration of the additive such as a metal salt and a surfactant is less than the lower limit, the surface potential of the wafer is not uniformized, and if the concentration exceeds the upper limit, the metal salt remaining on the wafer surface after etching and the surface activity are higher. The amount of the agent or the like becomes too large, and it becomes difficult to remove the agent by washing.
The etching solution thus prepared is maintained at 20 to 60 ° C. during etching. If the temperature is lower than 20 ° C., the etching rate becomes extremely slow. If the temperature exceeds 60 ° C., the surface roughness of the wafer increases. This temperature is preferably 30-50 ° C
It is. The etching time is 20-50 for the total etching amount.
It is determined to be about μm. The amount of etching depends on the amount of residual abrasive grains and the thickness of the affected layer.
【0012】本発明のエッチング液でシリコンウェーハ
をエッチングすると、次の式(2)の反応が行われる。 Si+2H2O+2OH-→Si(OH)2(O-)2+2H2↑ ……(2) 図1に示すように、ラッピングしたシリコンウェーハ
は、ラッピング後洗浄を兼ねたエッチング前洗浄が行わ
れ、上記エッチング液によるエッチングが行われ、エッ
チング後洗浄が行われた後、酸素ドナー消去のための熱
処理が行われる。このエッチング前洗浄とエッチング後
洗浄のために3〜6槽の洗浄槽が用いられ、エッチング
には1〜4槽のエッチング槽が用いられる。エッチング
槽を多槽にして、エッチング工程を数回に分けて行う
と、化学反応により発生する反応熱を分散させることが
でき、この反応熱に起因したウェーハ表面におけるエッ
チング速度のばらつきを最小限に抑えることができる。
ここで、図2に示した従来のエッチングプロセスにおけ
る洗浄槽と比べて、図1に示した洗浄槽の数がより少な
いのは次の理由による。即ち、本発明では、従来のよう
な混酸エッチングがエッチング工程中になく、反応速度
が比較的小さいアルカリエッチングが主体であるため、
液中で基板の表面電位をマイナスにし易い環境になる。
従って、持込まれたパーティクル及びラッピングパウダ
ーなどは、表面電位が同一となるため、除去し易い環境
になり、エッチング前後の洗浄槽を減らすことができ
る。エッチング前洗浄では洗浄液としてKOH又はNa
OH水溶液などのアルカリ水溶液が用いられ、主として
サイズの大きなパーティクルが除去される。またエッチ
ング後洗浄では洗浄液としてアンモニア過水が用いら
れ、主として小さなパーティクルが除去される。When a silicon wafer is etched with the etching solution of the present invention, a reaction represented by the following equation (2) is performed. Si + 2H 2 O + 2OH − → Si (OH) 2 (O − ) 2 + 2H 2 … (2) As shown in FIG. 1, the wrapped silicon wafer is subjected to pre-etching cleaning which also serves as post-lapping cleaning. After etching with an etchant and cleaning after etching are performed, heat treatment for erasing oxygen donors is performed. Three to six cleaning tanks are used for pre-etching cleaning and post-etching cleaning, and one to four etching tanks are used for etching. By using multiple etching tanks and performing the etching process in several steps, the heat of reaction generated by the chemical reaction can be dispersed, and variations in the etching rate on the wafer surface due to the heat of reaction can be minimized. Can be suppressed.
Here, the number of cleaning baths shown in FIG. 1 is smaller than that of the cleaning bath in the conventional etching process shown in FIG. 2 for the following reason. That is, in the present invention, the mixed acid etching as in the prior art is not performed during the etching process, and the reaction rate is mainly alkali etching, which is relatively small.
An environment in which the surface potential of the substrate is easily reduced to a negative value in the liquid.
Therefore, the introduced particles, wrapping powder, and the like have the same surface potential, so that the environment becomes easy to remove, and the number of cleaning tanks before and after etching can be reduced. In cleaning before etching, KOH or Na
An alkaline aqueous solution such as an OH aqueous solution is used, and mainly large particles are removed. In the post-etch cleaning, ammonia peroxide is used as a cleaning liquid, and mainly small particles are removed.
【0013】[0013]
【実施例】次に本発明の実施例を比較例とともに説明す
る。 <実施例1〜4>直径6インチ、抵抗率8〜11Ωcm
のシリコン単結晶インゴットをスライスし、ベベリング
し、その後両面をラッピングし、結晶面方位が(10
0)のラッピングウェーハを用意した。エッチングはこ
のラッピングウェーハをKOH水溶液で洗浄した後、乾
燥して行った。NH4OH/H2O=0.2(容積比)の
組成を有する溶液にCu(NO3)2を添加し、0.02p
pm、0.05ppm、0.1ppm、0.9ppmの
Cu2+イオンを含む4種類のエッチング液を用意した。
各エッチング液を4槽のエッチング槽に入れ、30℃の
温度に維持した後、これらのエッチング液に上記ラッピ
ングウェーハを順次浸漬してエッチングを行った。全エ
ッチング量が約30μmになるように、エッチング時間
を決めた。エッチング後、アンモニア過水と塩酸過水を
主要成分とする洗浄液で各ウェーハを洗浄し、乾燥し
た。Next, examples of the present invention will be described together with comparative examples. <Examples 1-4> Diameter 6 inches, resistivity 8-11 Ωcm
Is sliced, beveled, and then wrapped on both sides, and the crystal plane orientation is (10).
A lapping wafer of 0) was prepared. Etching was performed by washing the wrapping wafer with an aqueous KOH solution and then drying. Cu (NO 3 ) 2 was added to a solution having a composition of NH 4 OH / H 2 O = 0.2 (volume ratio), and 0.02 p
Four types of etching solutions containing Cu 2+ ions of pm, 0.05 ppm, 0.1 ppm, and 0.9 ppm were prepared.
Each etching solution was put into four etching baths and maintained at a temperature of 30 ° C., and then the lapping wafer was sequentially immersed in these etching solutions to perform etching. The etching time was determined so that the total etching amount was about 30 μm. After the etching, each wafer was washed with a cleaning solution mainly composed of aqueous ammonia and hydrogen peroxide, and dried.
【0014】<実施例5>実施例1と同一のラッピング
ウェーハについて、NH4OH/H2O=0.1(容積
比)の組成を有する溶液にCuSO4を添加し、0.0
8ppmのCu2+イオンを含むエッチング液を用意し、
実施例1と同様にエッチングした。エッチング前後の洗
浄と乾燥は実施例1と同様に行った。 <実施例6>実施例1と同一のラッピングウェーハにつ
いて、NH4OH/H2O=0.5(容積比)の組成を有
する溶液にNi(NO3)2を添加し、0.8ppmのNi
2+イオンを含むエッチング液を用意し、実施例1と同様
にエッチングした。エッチング前後の洗浄と乾燥は実施
例1と同様に行った。 <実施例7>実施例1と同一のラッピングウェーハにつ
いて、NH4OH/H2O=0.8(容積比)の組成を有
する溶液にFeCl2を添加し、0.5ppmのFe2+
イオンを含むエッチング液を用意し、実施例1と同様に
エッチングした。エッチング前後の洗浄と乾燥は実施例
1と同様に行った。Example 5 For the same lapping wafer as in Example 1, CuSO 4 was added to a solution having a composition of NH 4 OH / H 2 O = 0.1 (volume ratio), and
Prepare an etching solution containing 8 ppm of Cu 2+ ions,
Etching was performed in the same manner as in Example 1. Cleaning and drying before and after etching were performed in the same manner as in Example 1. Example 6 Ni (NO 3 ) 2 was added to a solution having a composition of NH 4 OH / H 2 O = 0.5 (volume ratio) for the same lapping wafer as in Example 1, and 0.8 ppm of Ni
An etching solution containing 2+ ions was prepared and etched in the same manner as in Example 1. Cleaning and drying before and after etching were performed in the same manner as in Example 1. Example 7 For the same lapping wafer as in Example 1, FeCl 2 was added to a solution having a composition of NH 4 OH / H 2 O = 0.8 (volume ratio), and 0.5 ppm of Fe 2+ was added.
An etching solution containing ions was prepared and etched in the same manner as in Example 1. Cleaning and drying before and after etching were performed in the same manner as in Example 1.
【0015】<比較例1〜3>実施例1と同一のラッピ
ングウェーハについて、NH4OH/H2O=0.2(容
積比)の組成を有する溶液にCu(NO3)2を添加し、
0.009ppm、1.2ppm、2.0ppmのCu
2+イオンを含む3種類のエッチング液を用意し、実施例
1と同様にエッチングした。エッチング前後の洗浄と乾
燥は実施例1と同様に行った。 <比較例4>実施例1と同一のラッピングウェーハにつ
いて、従来のNH4OH/H2O=0.2(容積比)の組
成を有する溶液によるアルカリエッチングを行った。即
ち、金属イオンも界面活性剤も含まないエッチング液を
単一のエッチング槽に入れ、80℃に維持した後、この
エッチング液に上記ラッピングウェーハを浸漬してエッ
チングを行った。全エッチング量が約30μmになるよ
うに、10分間ラッピングウェーハを浸漬した。エッチ
ング前洗浄はKOH水溶液で行い、エッチング後洗浄は
アンモニア過水で行った。<Comparative Examples 1 to 3> Cu (NO 3 ) 2 was added to a solution having a composition of NH 4 OH / H 2 O = 0.2 (volume ratio) for the same lapping wafer as in Example 1. ,
0.009 ppm, 1.2 ppm, 2.0 ppm Cu
Three types of etchants containing 2+ ions were prepared and etched in the same manner as in Example 1. Cleaning and drying before and after etching were performed in the same manner as in Example 1. Comparative Example 4 The same lapping wafer as in Example 1 was subjected to alkali etching using a solution having a conventional composition of NH 4 OH / H 2 O = 0.2 (volume ratio). That is, an etching solution containing neither a metal ion nor a surfactant was put into a single etching bath and maintained at 80 ° C., and then the lapping wafer was immersed in the etching solution to perform etching. The lapping wafer was immersed for 10 minutes so that the total etching amount was about 30 μm. The pre-etching cleaning was performed with a KOH aqueous solution, and the post-etching cleaning was performed with ammonia peroxide.
【0016】<実施例8>実施例1と同一のラッピング
ウェーハについて、KOH/H2O=0.35(重量
比)の組成を有する溶液にCu(NO3)2を添加し、0.
25ppmのCu2+イオンを含むエッチング液を用意
し、実施例1と同様にエッチングした。エッチング前後
の洗浄と乾燥は実施例1と同様に行った。 <実施例9>実施例1と同一のラッピングウェーハにつ
いて、KOH/H2O=0.35(重量比)の組成を有
する溶液にCuSO4を添加し、0.7ppmのCu2+
イオンを含むエッチング液を用意し、実施例1と同様に
エッチングした。エッチング前後の洗浄と乾燥は実施例
1と同様に行った。 <比較例5>実施例1と同一のラッピングウェーハにつ
いて、金属イオンも界面活性剤も含まない、従来のKO
H/H2O=0.6(重量比)の組成を有する溶液によ
るアルカリエッチングを比較例4と同様に行った。 <比較例6>実施例1と同一のラッピングウェーハにつ
いて、従来の混酸による酸エッチングを行った。即ち、
金属イオンも界面活性剤も含まない、HF/HNO3/
CH3COOH=3/5/3(容積比)のエッチング液
を用意し、このエッチング液を単一のエッチング槽に入
れ、40℃に維持した後、このエッチング液に上記ラッ
ピングウェーハを浸漬してエッチングを行った。全エッ
チング量が約30μmになるように、7分30秒間ラッ
ピングウェーハを浸漬した。エッチング前洗浄及び後洗
浄は比較例4と同様に行った。Example 8 For the same lapping wafer as in Example 1, Cu (NO 3 ) 2 was added to a solution having a composition of KOH / H 2 O = 0.35 (weight ratio).
An etching solution containing 25 ppm of Cu 2+ ions was prepared and etched in the same manner as in Example 1. Cleaning and drying before and after etching were performed in the same manner as in Example 1. Example 9 For the same lapping wafer as in Example 1, CuSO 4 was added to a solution having a composition of KOH / H 2 O = 0.35 (weight ratio), and 0.7 ppm of Cu 2+
An etching solution containing ions was prepared and etched in the same manner as in Example 1. Cleaning and drying before and after etching were performed in the same manner as in Example 1. <Comparative Example 5> For the same lapping wafer as in Example 1, the conventional KO containing neither metal ions nor surfactant was used.
Alkali etching using a solution having a composition of H / H 2 O = 0.6 (weight ratio) was performed in the same manner as in Comparative Example 4. Comparative Example 6 The same lapping wafer as in Example 1 was subjected to conventional acid etching with a mixed acid. That is,
HF / HNO 3 / containing neither metal ions nor surfactants
Prepare an etching solution of CH 3 COOH = 3/5/3 (volume ratio), put this etching solution in a single etching tank, maintain at 40 ° C., and immerse the lapping wafer in this etching solution. Etching was performed. The lapping wafer was immersed for 7 minutes and 30 seconds so that the total etching amount was about 30 μm. Pre-etching cleaning and post-etching cleaning were performed in the same manner as in Comparative Example 4.
【0017】<実施例10>実施例1と同一のラッピン
グウェーハについて、NH4OH/H2O=0.1(容積
比)の組成を有する溶液にアルキルナフタレンスルホン
酸ナトリウムを0.8重量%の割合で添加することによ
りエッチング液を用意し、実施例1と同様にエッチング
した。エッチング前後の洗浄と乾燥は実施例1と同様に
行った。 <実施例11>実施例1と同一のラッピングウェーハに
ついて、KOH/H2O=0.25(重量比)の組成を
有する溶液にアルキルナフタレンスルホン酸ナトリウム
を0.3重量%の割合で添加することによりエッチング
液を用意し、実施例1と同様にエッチングした。エッチ
ング前後の洗浄と乾燥は実施例1と同様に行った。 <比較例7>実施例1と同一のラッピングウェーハにつ
いて、KOH/H2O=0.25(重量比)の組成を有
する溶液にアルキルナフタレンスルホン酸ナトリウムを
1.2重量%の割合で添加することによりエッチング液
を用意し、実施例1と同様にエッチングした。エッチン
グ前後の洗浄と乾燥は実施例1と同様に行った。Example 10 For the same lapping wafer as in Example 1, 0.8% by weight of sodium alkylnaphthalenesulfonate was added to a solution having a composition of NH 4 OH / H 2 O = 0.1 (volume ratio). , An etching solution was prepared, and etching was performed in the same manner as in Example 1. Cleaning and drying before and after etching were performed in the same manner as in Example 1. For the same lapping wafers and <Example 11> Example 1, the addition of sodium alkyl naphthalene sulfonate solution having a composition of KOH / H 2 O = 0.25 (weight ratio) at a ratio of 0.3 wt% Thus, an etching solution was prepared and etched in the same manner as in Example 1. Cleaning and drying before and after etching were performed in the same manner as in Example 1. For the same lapping wafers and <Comparative Example 7> Example 1, the addition of sodium alkyl naphthalene sulfonate solution having a composition of KOH / H 2 O = 0.25 (weight ratio) at a ratio of 1.2 wt% Thus, an etching solution was prepared and etched in the same manner as in Example 1. Cleaning and drying before and after etching were performed in the same manner as in Example 1.
【0018】<実施例12>実施例1と同一のラッピン
グウェーハについて、NH4OH/H2O=0.25(容
積比)の組成を有する溶液にラウリルトリメチルアンモ
ニウムクロライドを0.9重量%の割合で添加すること
によりエッチング液を用意し、実施例1と同様にエッチ
ングした。エッチング前後の洗浄と乾燥は実施例1と同
様に行った。 <実施例13>実施例1と同一のラッピングウェーハに
ついて、KOH/H2O=0.25(重量比)の組成を
有する溶液にラウリルトリメチルアンモニウムクロライ
ドを0.5重量%の割合で添加することによりエッチン
グ液を用意し、実施例1と同様にエッチングした。エッ
チング前後の洗浄と乾燥は実施例1と同様に行った。 <比較例8>実施例1と同一のラッピングウェーハにつ
いて、KOH/H2O=0.3(重量比)の組成を有す
る溶液にラウリルトリメチルアンモニウムクロライドを
2.2重量%の割合で添加することによりエッチング液
を用意し、実施例1と同様にエッチングした。エッチン
グ前後の洗浄と乾燥は実施例1と同様に行った。Example 12 For the same lapping wafer as in Example 1, 0.9% by weight of lauryltrimethylammonium chloride was added to a solution having a composition of NH 4 OH / H 2 O = 0.25 (volume ratio). An etching solution was prepared by adding at a ratio, and etching was performed in the same manner as in Example 1. Cleaning and drying before and after etching were performed in the same manner as in Example 1. For the same lapping wafers and <Example 13> Example 1, the addition of lauryl trimethyl ammonium chloride in a proportion of 0.5 wt.% Solution having a composition of KOH / H 2 O = 0.25 (weight ratio) , An etching solution was prepared, and etching was performed in the same manner as in Example 1. Cleaning and drying before and after etching were performed in the same manner as in Example 1. Comparative Example 8 For the same lapping wafer as in Example 1, lauryl trimethylammonium chloride was added at a ratio of 2.2% by weight to a solution having a composition of KOH / H 2 O = 0.3 (weight ratio). , An etching solution was prepared, and etching was performed in the same manner as in Example 1. Cleaning and drying before and after etching were performed in the same manner as in Example 1.
【0019】<実施例14>実施例1と同一のラッピン
グウェーハについて、NH4OH/H2O=0.42(容
積比)の組成を有する溶液にラウリルベタインを1.7
重量%の割合で添加することによりエッチング液を用意
し、実施例1と同様にエッチングした。エッチング前後
の洗浄と乾燥は実施例1と同様に行った。 <実施例15>実施例1と同一のラッピングウェーハに
ついて、KOH/H2O=0.3(重量比)の組成を有
する溶液にラウリルベタインを0.9重量%の割合で添
加することによりエッチング液を用意し、実施例1と同
様にエッチングした。エッチング前後の洗浄と乾燥は実
施例1と同様に行った。 <比較例9>実施例1と同一のラッピングウェーハにつ
いて、KOH/H2O=0.3(重量比)の組成を有す
る溶液にラウリルベタインを3.1重量%の割合で添加
することによりエッチング液を用意し、実施例1と同様
にエッチングした。エッチング前後の洗浄と乾燥は実施
例1と同様に行った。Example 14 For the same lapping wafer as in Example 1, 1.7 of lauryl betaine was added to a solution having a composition of NH 4 OH / H 2 O = 0.42 (volume ratio).
An etching solution was prepared by adding at a ratio of% by weight, and etching was performed in the same manner as in Example 1. Cleaning and drying before and after etching were performed in the same manner as in Example 1. Example 15 The same lapping wafer as in Example 1 was etched by adding lauryl betaine at a ratio of 0.9% by weight to a solution having a composition of KOH / H 2 O = 0.3 (weight ratio). A liquid was prepared and etched in the same manner as in Example 1. Cleaning and drying before and after etching were performed in the same manner as in Example 1. Comparative Example 9 The same lapping wafer as in Example 1 was etched by adding lauryl betaine at a ratio of 3.1% by weight to a solution having a composition of KOH / H 2 O = 0.3 (weight ratio). A liquid was prepared and etched in the same manner as in Example 1. Cleaning and drying before and after etching were performed in the same manner as in Example 1.
【0020】<比較評価>実施例1〜9と比較例1〜6
のエッチング後の各ウェーハについて、各ウェーハに残
留するCu,Ni又はFeの量を測定した。また実施例
1〜15と比較例1〜9のエッチング後の各ウェーハに
ついて、各ウェーハを高平坦度のブロックプレートにワ
ックスで貼付けて片面研磨した後、マクロな形状精度で
ある平坦度(TTV:Total Thickness Variation)と
ミクロな形状精度である表面粗さ(SFQR:Site Foc
al Quality Range)を測定した。その結果を表1及び表
2に示す。 (a) TTV 各ウェーハをそれぞれ真空吸着盤に吸着固定した後、ウ
ェーハ表面の高さの最大値と最小値の差を求め、その値
をTTVとした。 (b) SFQR 各ウェーハを多数のサイトに分割し、各サイト内での基
準面を設け、その基準面から各サイトでのプラス側とマ
イナス側の最大変化量を測定し、このプラス側の最大変
化量の絶対値とマイナス側の最大変化量の絶対値との和
をSFQRとした。 (c) 残留するCu,Ni又はFeの量 各ウェーハの中央部にフッ酸と硝酸の混酸を滴下し、そ
の液滴がウェーハの全表面に行渡るように液滴を巡らし
た後、その液滴を回収して原子吸光分析法で分析するこ
とにより、残留するCu,Ni又はFeの量を求めた。
表1において、残留金属とは、エッチング液に含まれて
いた金属(例えばCu)がエッチングした後に残留する
当該金属(Cu)を意味する。<Comparative Evaluation> Examples 1 to 9 and Comparative Examples 1 to 6
The amount of Cu, Ni or Fe remaining on each wafer after the etching was measured. Further, for each of the etched wafers of Examples 1 to 15 and Comparative Examples 1 to 9, each wafer was attached to a high flatness block plate with wax and polished on one side, and then the flatness (TTV: Total Thickness Variation and Surface Roughness (SFQR: Site Foc)
al Quality Range) was measured. The results are shown in Tables 1 and 2. (a) TTV After each wafer was suction-fixed to a vacuum suction board, the difference between the maximum value and the minimum value of the wafer surface height was determined, and the value was defined as TTV. (b) SFQR Each wafer is divided into a number of sites, a reference plane is provided in each site, and the maximum change amount on each site is measured from the reference plane. The sum of the absolute value of the variation and the absolute value of the maximum variation on the minus side was defined as SFQR. (c) Remaining amount of Cu, Ni or Fe A mixed acid of hydrofluoric acid and nitric acid is dropped at the center of each wafer, and the liquid is circulated so that the liquid drops pass over the entire surface of the wafer. Drops were collected and analyzed by atomic absorption spectrometry to determine the amount of residual Cu, Ni or Fe.
In Table 1, the residual metal means the metal (Cu) remaining after the metal (eg, Cu) contained in the etching solution is etched.
【0021】[0021]
【表1】 [Table 1]
【0022】[0022]
【表2】 [Table 2]
【0023】金属イオンを含むエッチング液を用いてエ
ッチングした後では、残留金属の量は1×109原子/
cm2以下であることが求められる。表1から明らかな
ように、実施例1〜実施例9の金属イオンを含むエッチ
ング液のエッチング後の残留金属の量はすべて1×10
9原子/cm2以下である上、TTV及びSFQRはそれ
ぞれ1.0μm以下及び0.5μm以下の好ましい値を
示した。これに対して比較例1ではTTVが1.0μm
を上回り、比較例2では残留金属(Cu)の量が5×1
09原子/cm2であり、比較例3〜比較例6ではTT
V、SFQR及び残留金属(Cu)すべてについて実施
例1〜実施例9より劣っていた。また表2から明らかな
ように、実施例10及び実施例11は比較例7に比べ
て、実施例12及び実施例13は比較例8に比べて、更
に実施例14及び実施例15は比較例9に比べてTTV
及びSFQRについてそれぞれ良好な値を示した。After etching using an etching solution containing metal ions, the amount of residual metal is 1 × 10 9 atoms /
cm 2 or less. As is clear from Table 1, the amounts of residual metals after the etching of the etching solutions containing metal ions of Examples 1 to 9 were all 1 × 10
In addition to being 9 atoms / cm 2 or less, TTV and SFQR showed preferable values of 1.0 μm or less and 0.5 μm or less, respectively. On the other hand, in Comparative Example 1, the TTV was 1.0 μm.
In Comparative Example 2, the amount of residual metal (Cu) was 5 × 1
09 atoms / cm 2 , and in Comparative Examples 3 to 6, TT
All of V, SFQR and residual metal (Cu) were inferior to Examples 1 to 9. As is clear from Table 2, Examples 10 and 11 are compared with Comparative Example 7, Examples 12 and 13 are compared with Comparative Example 8, and Examples 14 and 15 are Comparative Examples. TTV compared to 9
And SFQR showed good values.
【0024】[0024]
【発明の効果】以上述べたように、本発明によれば、ア
ルカリ水溶液に金属塩、アニオン界面活性剤、カチオン
界面活性剤、両性界面活性剤又は極性基を有する有機高
分子を添加して調製されたエッチング液を20〜60℃
の温度にした後、このエッチング液にシリコンウェーハ
を浸漬してエッチングすることにより、シリコンウェー
ハのマクロな形状精度である平坦度とミクロな形状精度
である表面粗さの双方を良好にすることができる。特
に、本発明の方法ではエッチング前後の洗浄槽及びエッ
チング槽が従来と比べて少なくて済み、エッチングコス
トを安価にすることができる利点もある。As described above, according to the present invention, a metal salt, an anionic surfactant, a cationic surfactant, an amphoteric surfactant or an organic polymer having a polar group is added to an aqueous alkaline solution. 20 to 60 ° C
After immersing the silicon wafer in this etchant after etching at a temperature of not more than two, it is possible to improve both the flatness, which is the macro shape accuracy, and the surface roughness, which is the micro shape accuracy, of the silicon wafer. it can. In particular, in the method of the present invention, the number of cleaning tanks and etching tanks before and after etching can be reduced as compared with the conventional method, and there is also an advantage that the etching cost can be reduced.
【図1】本発明のエッチング工程及びエッチング前後の
工程を示す図。FIG. 1 is a diagram showing an etching step of the present invention and steps before and after etching.
【図2】従来のエッチング工程及びエッチング前後の工
程を示す図。FIG. 2 is a diagram showing a conventional etching step and steps before and after etching.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 高石 和成 東京都千代田区大手町1丁目5番1号 三 菱マテリアルシリコン株式会社内 (72)発明者 遠藤 光弘 東京都千代田区大手町1丁目5番1号 三 菱マテリアルシリコン株式会社内 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazunari Takaishi 1-5-1, Otemachi, Chiyoda-ku, Tokyo Within Mitsubishi Materials Silicon Co., Ltd. (72) Inventor Mitsuhiro Endo 1-5, Otemachi, Chiyoda-ku, Tokyo No. 1 Mitsubishi Materials Silicon Corporation
Claims (7)
活性剤、カチオン界面活性剤、両性界面活性剤又は極性
基を有する有機高分子を添加して調製されたエッチング
液を20〜60℃の温度にした後、前記エッチング液に
シリコンウェーハを浸漬してエッチングすることを特徴
とするシリコンウェーハのエッチング方法。An etching solution prepared by adding a metal salt, an anionic surfactant, a cationic surfactant, an amphoteric surfactant or an organic polymer having a polar group to an aqueous alkali solution is heated to a temperature of 20 to 60 ° C. And etching the silicon wafer by immersing the silicon wafer in the etching solution.
aOH水溶液、KOH水溶液又はエチレンジアミン水溶
液であって、容積比でNH4OH/H2O=0.01〜
1.0、重量比でNaOH/H2O=0.2〜0.5、
重量比でKOH/H2O=0.2〜0.5又は重量比で
H2NCH2CH2NH2/H2O=0.2〜0.5の組成
を有する請求項1記載のエッチング方法。2. The method according to claim 1, wherein the aqueous alkaline solution is an aqueous NH 4 OH solution,
an aOH aqueous solution, a KOH aqueous solution, or an ethylenediamine aqueous solution, wherein NH 4 OH / H 2 O = 0.01 to
1.0, NaOH in a weight ratio / H 2 O = 0.2~0.5,
Etching of claim 1 having a composition of H 2 NCH 2 CH 2 NH 2 / H 2 O = 0.2~0.5 with KOH / H 2 O = 0.2~0.5 or weight by weight ratio Method.
硫酸塩又は塩化物であって、エッチング液がアルカリ水
溶液に0.01〜1.0ppmの割合で前記Cu,Ni
又はFeの金属イオンを含んで調製された請求項1又は
2記載のエッチング方法。3. The metal salt is a nitrate of Cu, Ni or Fe,
A sulfate or a chloride, wherein the etching solution is contained in an alkaline aqueous solution at a rate of 0.01 to 1.0 ppm of the Cu, Ni
3. The etching method according to claim 1, wherein the etching method is prepared by containing a metal ion of Fe.
ンスルホン酸ナトリウム、アルキルジフェニルエーテル
ジスルホン酸ナトリウム又はアルキルリン酸カリウムで
あって、エッチング液がアルカリ水溶液に0.1〜2.
0重量%の割合で前記アニオン界面活性剤を含んで調製
された請求項1記載のエッチング方法。4. The method according to claim 1, wherein the anionic surfactant is sodium alkylnaphthalenesulfonate, sodium alkyldiphenyletherdisulfonate or potassium alkylphosphate, and the etching solution is 0.1 to 2.
2. The etching method according to claim 1, wherein said etching method is prepared by containing said anionic surfactant in a proportion of 0% by weight.
ルアンモニウムクロライド、ステアリルトリメチルアン
モニウムクロライド又はステアリルアミンアセテートで
あって、エッチング液がアルカリ水溶液に0.1〜2.
0重量%の割合で前記カチオン界面活性剤を含んで調製
された請求項1記載のエッチング方法。5. The method according to claim 1, wherein the cationic surfactant is lauryltrimethylammonium chloride, stearyltrimethylammonium chloride or stearylamine acetate.
2. The etching method according to claim 1, wherein said etching method is prepared by containing said cationic surfactant in a ratio of 0% by weight.
テアリルベタイン又はラウリルジメチルアミンオキサイ
ドであって、エッチング液がアルカリ水溶液に0.1〜
2.0重量%の割合で前記両性界面活性剤を含んで調製
された請求項1記載のエッチング方法。6. The amphoteric surfactant is lauryl betaine, stearyl betaine or lauryl dimethylamine oxide, and the etching solution is 0.1 to 0.1% in alkaline aqueous solution.
2. The etching method according to claim 1, wherein the amphoteric surfactant is prepared at a ratio of 2.0% by weight.
ン酸型高分子、ポリカルボン酸型高分子又はポリスルホ
ン酸型高分子であって、エッチング液がアルカリ水溶液
に0.1〜2.0重量%の割合で前記有機高分子を含ん
で調製された請求項1記載のエッチング方法。7. The organic polymer having a polar group is a polysulfonic acid type polymer, a polycarboxylic acid type polymer or a polysulfonic acid type polymer, and the etching solution is 0.1 to 2.0% by weight in an alkaline aqueous solution. The etching method according to claim 1, wherein the etching method is prepared by containing the organic polymer in a ratio of:
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|---|---|---|---|
| JP24526498A JP3686910B2 (en) | 1997-09-29 | 1998-08-31 | Etching method of silicon wafer |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9-263700 | 1997-09-29 | ||
| JP26370097 | 1997-09-29 | ||
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|---|---|---|---|
| JP2003209230A Division JP3876857B2 (en) | 1997-09-29 | 2003-08-28 | Etching method of silicon wafer |
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| Publication Number | Publication Date |
|---|---|
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| JP3686910B2 JP3686910B2 (en) | 2005-08-24 |
Family
ID=26537136
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| Country | Link |
|---|---|
| JP (1) | JP3686910B2 (en) |
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| US9868902B2 (en) | 2014-07-17 | 2018-01-16 | Soulbrain Co., Ltd. | Composition for etching |
| US10465112B2 (en) | 2014-07-17 | 2019-11-05 | Soulbrain Co., Ltd. | Composition for etching |
| JP2016072522A (en) * | 2014-09-30 | 2016-05-09 | 株式会社カネカ | Manufacturing method of silicon substrate for solar cell, manufacturing method of solar cell, and manufacturing method of solar cell module |
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