JP2906755B2 - Chemical purity evaluation method - Google Patents
Chemical purity evaluation methodInfo
- Publication number
- JP2906755B2 JP2906755B2 JP3219729A JP21972991A JP2906755B2 JP 2906755 B2 JP2906755 B2 JP 2906755B2 JP 3219729 A JP3219729 A JP 3219729A JP 21972991 A JP21972991 A JP 21972991A JP 2906755 B2 JP2906755 B2 JP 2906755B2
- Authority
- JP
- Japan
- Prior art keywords
- chemical solution
- wafer
- chemical
- concentration
- metal impurities
- 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.)
- Expired - Lifetime
Links
Description
【０００１】[0001]
【産業上の利用分野】本発明は、薬液の純度評価法に関
し、特に薬液中の金属不純物を高感度に分析するための
薬液の純度評価法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating the purity of a chemical solution, and more particularly to a method for evaluating the purity of a chemical solution for analyzing metal impurities in the chemical solution with high sensitivity.
【０００２】[0002]
【従来の技術】ＬＳＩの高集積化に伴い、製造プロセス
で使用される材料の高純度化が重要になってきている。
ウェハーのクリーニングを行う洗浄工程で使用される薬
液（純水を含む）の純度は、ウェハーの最終的な清浄度
を左右するため、特に高純度であることが要求される。
今後の超高集積デバイスの製造で使用される薬液中の金
属不純物濃度は、薬液の種類、あるいは元素によっては
１ｐｐｂ，あるいは０．１ｐｐｂ以下に抑える必要があ
る。従って、純度を管理するための評価技術には、管理
濃度よりもさらに１桁以上の感度が要求されるため、
０．１ｐｐｂ、あるいは０．０１ｐｐｂ以下の感度が要
求されることになる。2. Description of the Related Art As LSIs have become more highly integrated, it has become important to purify materials used in manufacturing processes.
The purity of the chemical solution (including pure water) used in the cleaning process for cleaning the wafer is required to be particularly high because the final cleanliness of the wafer is affected.
The concentration of metal impurities in a chemical used in the production of ultra-highly integrated devices in the future needs to be suppressed to 1 ppb or 0.1 ppb or less depending on the type of chemical or the element. Therefore, the evaluation technique for controlling the purity requires sensitivity that is at least one order of magnitude higher than the control concentration.
A sensitivity of 0.1 ppb or less is required.
【０００３】従来、これらの薬液中の金属不純物の分析
は、薬液槽から薬液をサンプリング容器に採取し、原子
吸光、ＩＣＰ−ＭＳなどの高感度分析装置で分析を行っ
ていた。ほとんどの薬液については、マトリックスの影
響で、直接、分析装置に導入することは困難で、純水で
希釈するか、加熱濃縮によりマトリックス成分を除去す
るなどの前処理操作を行った後、分析を行っていた。Heretofore, analysis of metal impurities in these chemicals has been performed by collecting a chemical from a chemical tank into a sampling vessel and analyzing it with a high-sensitivity analyzer such as atomic absorption or ICP-MS. It is difficult to introduce most chemicals directly into the analyzer due to the influence of the matrix.After performing pretreatment operations such as diluting with pure water or removing matrix components by heat concentration, the analysis is performed. I was going.
【０００４】[0004]
【発明が解決しようとする課題】従来技術においては、
以下のような問題点があった。１）薬液槽からの薬液の
サンプリングは煩雑で、かつ危険を伴いやすいだけでな
く、コンタミネーションの原因になる、２）サンプリン
グ容器自体からの不純物の溶出の可能性がある、３）純
水希釈分析では高感度分析ができない、４）加熱濃縮操
作には、数時間を要し、操作中のかつコンタミネーショ
ンの可能性が高い。従って、従来技術においては、操作
が煩雑で、長時間を要するだけでなく、０．１ｐｐｂ以
下の高感度分析を行うためにコンタミネーションコント
ロールを厳密に行う必要があり、分析者に高度な分析技
術と熟練が要求されるという問題があった。In the prior art,
There were the following problems. 1) Sampling of a chemical solution from a chemical solution tank is not only complicated and liable to be dangerous, but also causes contamination. 2) There is a possibility of elution of impurities from the sampling container itself. 3) Pure water dilution The analysis cannot perform high-sensitivity analysis. 4) The heating and concentration operation requires several hours, and there is a high possibility of contamination during the operation. Therefore, in the prior art, the operation is complicated and not only takes a long time, but also it is necessary to strictly control the contamination in order to perform a high-sensitivity analysis of 0.1 ppb or less. There was a problem that skill was required.
【０００５】本発明の目的は、従来技術の問題点を解決
し、薬液中の０．１ｐｐｂ以下の金属不純物の分析が行
え、薬液のサンプリングが不用で、かつ前処理操作が短
時間にかつ簡便に行える薬液の純度評価法を提供するこ
とにある。An object of the present invention is to solve the problems of the prior art, to analyze metal impurities of 0.1 ppb or less in a chemical solution, to eliminate the need for sampling of a chemical solution, and to perform a pretreatment operation in a short time and simply. It is an object of the present invention to provide a method for evaluating the purity of a chemical solution which can be performed in a short time.
【０００６】[0006]
【課題を解決するための手段】前記目的を達成するた
め、本発明に係わる純度評価法においては、表面を清浄
化したシリコンウェハーを薬液に一定時間浸漬した後、
水洗・乾燥し、当該ウェハー表面に付着した金属不純物
を分析するものである。また、ウェハー表面に付着した
金属不純物をフッ酸蒸気で分解し、分解物を回収液で回
収し、当該回収液中の金属不純物を高感度分析装置で分
析するものである。In order to achieve the above object, in the purity evaluation method according to the present invention, a silicon wafer whose surface has been cleaned is immersed in a chemical solution for a certain period of time.
It is washed and dried to analyze metal impurities attached to the wafer surface. Further, the metal impurities attached to the wafer surface are decomposed by hydrofluoric acid vapor, the decomposed product is collected by a recovery liquid, and the metal impurities in the recovery liquid are analyzed by a high-sensitivity analyzer.
【０００７】[0007]
【作用】ＬＳＩ製造用洗浄液として酸やアルカリと過酸
化水素との混合液、あるいはフッ酸などの薬液が使用さ
れる。シリコンウェハーをこれらの薬液に浸漬するとウ
ェハー表面に金属不純物が付着する。A mixed solution of an acid or alkali and hydrogen peroxide, or a chemical such as hydrofluoric acid is used as a cleaning liquid for LSI production. When a silicon wafer is immersed in these chemicals, metal impurities adhere to the wafer surface.
【０００８】例えば、アンモニア−過酸化水素混合液に
ウェハーを浸漬するとウェハー表面に自然酸化膜が生成
するが、シリコンよりも酸化物生成エンタルピーの大き
いＡｌやＦｅなどの元素は、自然酸化膜中に取り込まれ
る形で付着する。また、フッ酸にウェハーを浸漬する
と、表面の自然酸化膜が除去され、金属シリコン面が露
出するため、シリコンよりもイオン化傾向の小さいＣｕ
やＡｕなどの金属は酸化還元反応によりウェハー表面に
析出し、付着する。For example, when a wafer is immersed in a mixed solution of ammonia and hydrogen peroxide, a natural oxide film is formed on the wafer surface. Elements such as Al and Fe, which have a larger enthalpy of oxide formation than silicon, are contained in the natural oxide film. Attached in the form of being taken in. Further, when the wafer is immersed in hydrofluoric acid, the natural oxide film on the surface is removed and the metal silicon surface is exposed.
Metals such as Au and Au precipitate and adhere to the wafer surface by an oxidation-reduction reaction.
【０００９】ウェハー表面への付着濃度は、薬液中濃度
に対応することがわかっている。従って、薬液中の不純
物濃度のウェハー表面への付着濃度の関係を求めておけ
ば、ウェハー表面の濃度を分析することにより薬液中の
濃度を求められる。[0009] It has been found that the concentration attached to the wafer surface corresponds to the concentration in the chemical solution. Therefore, if the relationship between the impurity concentration in the chemical solution and the adhesion concentration on the wafer surface is determined, the concentration in the chemical solution can be determined by analyzing the concentration on the wafer surface.
【００１０】[0010]
【実施例】次に、本発明について図面を参照して説明す
る。Next, the present invention will be described with reference to the drawings.
【００１１】（実施例１）図１は、本発明の実施例１を
示す評価操作のフローチャート図である。本実施例では
アンモニア−過酸化水素混合液の純度評価例を示す。表
面を清浄化したウェハーを図２に示すように薬液中に浸
漬する。図２において、シリコンウェハー１はウェハー
キャリア２にセットして、薬液槽３内のアンモニア−過
酸化水素混合液４に浸漬する。一定時間浸漬し、水洗・
乾燥後、ウェハー表面に付着した金属不純物濃度を分析
する。分析の前処理操作として、ウェハー表面に付着し
た金属不純物をフッ酸蒸気で分解し、分解物を回収液で
回収し、当該回収液中のＡｌとＦｅの濃度を黒鉛炉原子
吸光法（フッ酸蒸気分解−原子吸光法）で分析する。(Embodiment 1) FIG. 1 is a flowchart of an evaluation operation according to Embodiment 1 of the present invention. In this embodiment, an example of evaluating the purity of an ammonia-hydrogen peroxide mixture will be described. The wafer whose surface has been cleaned is immersed in a chemical solution as shown in FIG. In FIG. 2, a silicon wafer 1 is set on a wafer carrier 2 and immersed in an ammonia-hydrogen peroxide mixed solution 4 in a chemical solution tank 3. Soak for a certain time,
After drying, the concentration of metal impurities attached to the wafer surface is analyzed. As a pre-processing operation of the analysis, metal impurities attached to the wafer surface are decomposed by hydrofluoric acid vapor, the decomposed product is recovered by a recovery solution, and the concentrations of Al and Fe in the recovery solution are measured by a graphite furnace atomic absorption method (hydrofluoric acid). (Vapor decomposition-atomic absorption method).
【００１２】アンモニア−過酸化水素混合液中のＡｌと
Ｆｅの濃度のウェハー表面に付着した濃度の関係を図３
に示す。この場合、薬液組成は、ＮＨ４０Ｈ：Ｈ２０
２：Ｈ２０＝１：１：５で、薬液温度は７０℃、浸漬時
間は１０分である。両者の間に直線的な相関があり、ウ
ェハー表面濃度から薬液中濃度が簡単に求められる。FIG. 3 shows the relationship between the concentration of Al and Fe in the ammonia-hydrogen peroxide mixture and the concentration attached to the wafer surface.
Shown in In this case, the chemical composition is NH40H: H20
2: H20 = 1: 1: 5, chemical temperature 70 ° C., immersion time 10 minutes. There is a linear correlation between the two, and the concentration in the chemical solution can be easily obtained from the wafer surface concentration.
【００１３】フッ酸蒸気分解−原子吸光法でのＡｌ，Ｆ
ｅの定量下限は各々、２ｘ１０の９乗，１×１０の９乗
原子／平方センチメートルであることから、図３より本
法での薬液中のこれらの元素の定量下限は０．０１ｐｐ
ｂであり、要求レベルを満足する分析感度が得られる。Al, F by hydrofluoric acid vapor decomposition-atomic absorption method
Since the lower limit of quantification of e is 2 × 10 ninth power and 1 × 10 ninth atom / square centimeter, respectively, the lower limit of quantification of these elements in the chemical solution by this method is 0.01 pp from FIG.
b, an analytical sensitivity satisfying the required level can be obtained.
【００１４】ウェハー表面への付着濃度は、浸漬時間に
より変化するが、浸漬時間を一定にすれば再現性があ
る。従って、浸漬時間は任意でよい。本法で分析できる
元素（ウェハー表面に付着する元素）は、上述したよう
にシリコンよりも酸化物生成エンタルピーの大きい元素
に限定されるが、ＬＳＩ製造上、ウェハー表面に付着し
てデバイス特性を劣化させるのはこれらの元素であり、
薬液純度管理上、これらの元素が分析できればよい。The adhesion concentration on the wafer surface changes depending on the immersion time, but reproducibility can be obtained by keeping the immersion time constant. Therefore, the immersion time may be arbitrary. The elements that can be analyzed by this method (elements adhering to the wafer surface) are limited to elements having a larger enthalpy of oxide formation than silicon, as described above. However, in LSI manufacturing, they adhere to the wafer surface and deteriorate device characteristics. It is these elements that make
It is sufficient that these elements can be analyzed in order to control the chemical purity.
【００１５】本法においては、従来技術の薬液サンプリ
ングに該当するウェハー浸漬操作は通常作業であり、サ
ンプリングで従来問題となった点は解決できた。また、
分析の前処理操作（フッ酸蒸気分解）に要する時間は５
分／サンプル以内であり、前処理時間も数十分の１に短
縮でき、コンタミネーションも大幅に低減できた。In the present method, the wafer immersion operation corresponding to the prior art chemical solution sampling is a normal operation, and the problems that have conventionally been encountered in sampling can be solved. Also,
The time required for the analysis pretreatment operation (hydrofluoric acid vapor decomposition) is 5
Within minutes / sample, the pretreatment time could be reduced to several tenths, and contamination could be significantly reduced.
【００１６】（実施例２）図４は、本発明の実施例２を
示す評価操作のフローチャート図である。本実施例は、
フッ酸の純度評価例を示す。ウェハーを浸漬する薬液が
フッ酸に変わっている以外は、実施例１と同様である。(Embodiment 2) FIG. 4 is a flowchart of an evaluation operation according to Embodiment 2 of the present invention. In this embodiment,
An example of evaluating the purity of hydrofluoric acid is shown. Example 1 is the same as Example 1 except that the chemical for immersing the wafer is changed to hydrofluoric acid.
【００１７】フッ酸中のＣｕ濃度とウェハー表面付着濃
度の関係を図５に示す。この場合、薬液組成は、ＨＦ：
Ｈ２０＝１：４９、薬液温度は室温、ウェハー浸漬時間
は１０分である。FIG. 5 shows the relationship between the Cu concentration in hydrofluoric acid and the concentration on the wafer surface. In this case, the chemical composition is HF:
H20 = 1: 49, chemical temperature is room temperature, and wafer immersion time is 10 minutes.
【００１８】フッ酸蒸気分解法でのＣｕの定量下限は５
×１０の８乗原子／平方センチメートルであることか
ら、本法での薬液中Ｃｕの定量下限は第５図から０．１
ｐｐｂであり、要求レベルを満足できる分析感度が得ら
れる。The lower limit of quantification of Cu by hydrofluoric acid vapor decomposition is 5
Since it is × 10 8 atoms / square centimeter, the lower limit of quantification of Cu in the chemical solution in this method is 0.1 from FIG.
ppb, and an analysis sensitivity that satisfies the required level can be obtained.
【００１９】[0019]
【発明の効果】以上説明したように本発明の薬液の純度
評価法によれば、従来問題となっていた薬液槽からの薬
液のサンプリングも不用になり、分析の前処理操作にお
いても、処理時間が５分／サンプル以内と、従来の数十
分の１に短縮でき、コンタミネーションも大幅に低減で
きた。As described above, according to the method for evaluating the purity of a chemical solution of the present invention, sampling of a chemical solution from a chemical solution tank, which has been a problem in the past, becomes unnecessary, and the processing time can be reduced even in the pre-processing operation for analysis. Was less than 5 minutes / sample, which is one-tenth of the conventional value, and the contamination was significantly reduced.
【図１】本発明の実施例１を示す評価操作のフローチャ
ート図である。FIG. 1 is a flowchart illustrating an evaluation operation according to a first embodiment of the present invention.
【図２】実施例１の説明図である。FIG. 2 is an explanatory diagram of the first embodiment.
【図３】実施例１の説明図である。FIG. 3 is an explanatory diagram of the first embodiment.
【図４】本発明の実施例２を示す評価操作のフローチャ
ート図である。FIG. 4 is a flowchart illustrating an evaluation operation according to a second embodiment of the present invention.
【図５】実施例２の説明図である。FIG. 5 is an explanatory diagram of a second embodiment.
１ シリコンウェハー ２ ウェハーキャリア ３ 薬液槽 ４ アンモニア−過酸化水素混合液 DESCRIPTION OF SYMBOLS 1 Silicon wafer 2 Wafer carrier 3 Chemical tank 4 Ammonia-hydrogen peroxide mixture
Claims (2)
液に一定時間浸漬した後、水洗・乾燥し、当該ウェハー
表面に付着した金属不純物を分析することを特徴とする
薬液の純度評価法。1. A method for evaluating the purity of a chemical solution, comprising immersing a silicon wafer having a cleaned surface in a chemical solution for a certain period of time, washing and drying, and analyzing metal impurities attached to the wafer surface.
ッ酸蒸気で分解し、分解物を回収液で回収し、当該回収
液中の金属不純物を高感度分析装置で分析することを特
徴とする請求項１記載の薬液の純度評価法。2. The method according to claim 1, wherein metal impurities adhering to the wafer surface are decomposed by hydrofluoric acid vapor, the decomposed product is collected by a recovery liquid, and the metal impurities in the recovery liquid are analyzed by a high-sensitivity analyzer. Item 4. A method for evaluating the purity of a drug solution according to Item 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3219729A JP2906755B2 (en) | 1991-08-30 | 1991-08-30 | Chemical purity evaluation method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3219729A JP2906755B2 (en) | 1991-08-30 | 1991-08-30 | Chemical purity evaluation method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0562958A JPH0562958A (en) | 1993-03-12 |
| JP2906755B2 true JP2906755B2 (en) | 1999-06-21 |
Family
ID=16740063
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3219729A Expired - Lifetime JP2906755B2 (en) | 1991-08-30 | 1991-08-30 | Chemical purity evaluation method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2906755B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8192994B2 (en) | 1998-02-10 | 2012-06-05 | Angros Lee H | Method of applying a biological specimen to an analytic plate |
| US6713304B2 (en) | 1998-02-10 | 2004-03-30 | Lee H. Angros | Method of forming a containment border on an analytic plate |
| WO2006113523A2 (en) | 2005-04-15 | 2006-10-26 | Angros Lee H | Analytic substrate coating apparatus and method |
| CN112713103B (en) * | 2021-03-29 | 2021-06-25 | 西安奕斯伟硅片技术有限公司 | Method for measuring metal content in silicon wafer |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5642344A (en) * | 1979-09-14 | 1981-04-20 | Fujitsu Ltd | Evaluation for wafer washing |
| JPH01241131A (en) * | 1988-03-23 | 1989-09-26 | Oki Electric Ind Co Ltd | Removal of resist residue |
-
1991
- 1991-08-30 JP JP3219729A patent/JP2906755B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0562958A (en) | 1993-03-12 |
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