JPH07249666A - Iron concentration measurement method of silicon wafer - Google Patents
Iron concentration measurement method of silicon waferInfo
- Publication number
- JPH07249666A JPH07249666A JP6809194A JP6809194A JPH07249666A JP H07249666 A JPH07249666 A JP H07249666A JP 6809194 A JP6809194 A JP 6809194A JP 6809194 A JP6809194 A JP 6809194A JP H07249666 A JPH07249666 A JP H07249666A
- Authority
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- Japan
- Prior art keywords
- silicon wafer
- measured
- diffusion length
- iron concentration
- state
- Prior art date
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- Crystals, And After-Treatments Of Crystals (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、シリコンウェーハの鉄
濃度測定方法に係り、特に欠陥を高密度に発生している
シリコンウェーハの鉄濃度測定方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring iron concentration in a silicon wafer, and more particularly to a method for measuring iron concentration in a silicon wafer in which defects are generated at high density.
【０００２】[0002]
【従来の技術】従来、シリコンウェーハの鉄濃度測定方
法は、次の方法が知られている。 （イ）シリコンウェーハ表面にショットキー接合又はＰ
／Ｎ接合を形成し、ＤＬＴＳ法（Ｄｅｅｐ ｌｅｖｅｌ
ｔｒａｎｇｅｎｔ ｓｐｅｃｔｒｏ ｓｃｏｐｅ法）
によりＦｅが作る深い準位の密度を測定する。この方法
は、例えばＤｉａｇｎｏｓｔｉｃ Ｔｅｃｈｎｉｑｕｅ
ｓ ｆｏｒ Ｓｅｍｉｃｏｎｄｕｃｔｏｒ Ｄｅｖｉｃ
ｅ ａｎｄ Ｍａｔｅｒｉａｌｓ（１８０ｔｈ ＥＣＳ
Ｍｅｅｔｉｎｇ、ｐ．１１３〜１１８（１９９１）、
Ｐｕｂｌｉｓｈｅｄ ｉｎ１９９２）において示されて
いる。2. Description of the Related Art Conventionally, the following methods have been known as methods for measuring the iron concentration of silicon wafers. (A) Schottky junction or P on the silicon wafer surface
/ N junction is formed, and DLTS method (Deep level)
(transparent spectroscope method)
To measure the density of the deep level created by Fe. This method is, for example, a Diagnostic Technique.
s for Semiconductor Device
e and Materials (180th ECS
Meeting, p. 113-118 (1991),
Published in 1992).
【０００３】（ロ）シリコンウェーハの表面を、光照射
による光学励起または２００℃加熱により活性化させ、
この活性化の前後における、鉄ーボロン解離等による拡
散長変化を測定し、これに基づき鉄の濃度を定量する表
面光起電圧法（Ｓｕｒｆａｃｅ ｐｈｏｔｏｖｏｌｔａ
ｇｅ法、以下ＳＰＶ法という。）が知られており、例え
ばＳＰＶ法による重金属汚染測定（ワークショップ資
料、１９９３年１１月１６日、日本エー・ディー・イー
株式会社）において示されている。図５に、このＳＰＶ
法によるシリコンウェーハの鉄濃度測定の手順概要（ス
テップ４１〜ステップ４５）を示す。まず所定の処理後
（ａｓ ｐｒｏｃｅｓｓｅｄ）のＦｅ−Ｂ結合状態のシ
リコンウェーハが用意され（ステップ４１）、シリコン
ウェーハの少数キャリアの拡散長Ｌｂを表面光起電圧法
により測定し（ステップ４２）、次にシリコンウェーハ
を２００℃加熱等により、Ｆｅ−Ｂ→Ｆｅint ＋Ｂとな
る解離を生じさせた後に、シリコンウェーハを室温まで
急冷し（ステップ４３）、解離状態の少数キャリアの拡
散長Ｌａを測定し（ステップ４４）、鉄濃度を算出する
（ステップ４５）。この鉄濃度［Ｆｅ］は、［Ｆｅ］≒
１×１０16（Ｌａ-2−Ｌｂ-2）より算出される。ここ
で、鉄濃度［Ｆｅ］の単位はｃｍ-3、ＬａおよびＬｂの
単位はμｍである。この方法により、鉄濃度を高感度
（１０8 ｃｍ-3オーダー）に測定可能としている。(B) The surface of a silicon wafer is activated by optical excitation by light irradiation or heating at 200 ° C.,
Before and after this activation, a change in diffusion length due to iron-boron dissociation or the like is measured, and the concentration of iron is quantified based on the measurement. The surface photovoltage method (Surface photovolta)
The ge method, hereinafter referred to as SPV method. ) Is known, and is shown in, for example, heavy metal contamination measurement by SPV method (workshop data, November 16, 1993, Japan AD Corporation). This SPV is shown in FIG.
The procedure outline (step 41 to step 45) of the iron concentration measurement of the silicon wafer by the method is shown. First, a silicon wafer in an Fe-B bonded state after a predetermined process (as processed) is prepared (step 41), and the minority carrier diffusion length Lb of the silicon wafer is measured by the surface photovoltage method (step 42). After causing the dissociation of Fe-B → Fe int + B by heating the silicon wafer at 200 ° C. or the like, the silicon wafer is rapidly cooled to room temperature (step 43), and the diffusion length La of the dissociated minority carriers is measured ( In step 44), the iron concentration is calculated (step 45). This iron concentration [Fe] is [Fe] ≈
It is calculated from 1 × 10 16 (La −2 −Lb −2 ). Here, the unit of iron concentration [Fe] is cm −3 , and the units of La and Lb are μm. By this method, the iron concentration can be measured with high sensitivity (10 8 cm −3 order).
【０００４】[0004]
【発明が解決しようとする課題】しかしながら、上記従
来技術には次のような問題点がある。すなわち、（イ）
においては、接合形成およびＤＬＴＳ測定に長い時間を
要し、例えば、真空蒸着による接合形成に１時間、さら
に１点のＤＬＴＳ測定時間が１時間以上と多大な工数を
必要とする問題がある。次に、（ロ）においては、酸素
析出誘起欠陥等の欠陥が高密度の発生しているシリコン
ウェーハでは、鉄濃度［Ｆｅ］を実際よりも大きな値と
して算出する問題がある。すなわち、シリコンウェーハ
厚さ方向におけるキャリアの再結合中心（酸素析出誘起
欠陥、Ｆｅ−Ｂ、格子間のＦｅなど）の分布が均一でな
い場合には、正確な少数キャリアの拡散長Ｌａ、Ｌｂが
求められない。例えば、３ステップＩＧ（内部ゲッタリ
ング）処理を施したシリコンウェーハでは、両端面部に
無欠陥層を形成しており、酸素析出誘起欠陥等の欠陥の
分布が不均一な構造となるので、無欠陥層の影響を受け
る拡散長Ｌａ、Ｌｂを測定することになる。また、無欠
陥層をエッチング等により除去し、再結合中心の厚さ方
向における分布の均一性を確保したとしても、欠陥が高
密度に発生しているシリコンウェーハでは、２００℃加
熱などにより活性化する再結合中心が、Ｆｅ−Ｂ以外に
も存在するためである。However, the above-mentioned prior art has the following problems. That is, (a)
In the above, there is a problem that it takes a long time to form a junction and to measure DLTS, and for example, it takes 1 hour to form a junction by vacuum vapor deposition, and the time required to measure one DLTS is 1 hour or more, which is a large number of steps. Next, in (b), there is a problem that the iron concentration [Fe] is calculated as a value larger than the actual value in a silicon wafer in which defects such as oxygen precipitation-induced defects are generated at a high density. That is, when the distribution of carrier recombination centers (oxygen precipitation induced defects, Fe-B, interstitial Fe, etc.) in the thickness direction of the silicon wafer is not uniform, accurate diffusion lengths La and Lb of minority carriers are obtained. I can't. For example, in a silicon wafer that has been subjected to a three-step IG (internal gettering) process, defect-free layers are formed on both end faces, and the distribution of defects such as oxygen precipitation-induced defects is non-uniform. The diffusion lengths La and Lb affected by the layers will be measured. Further, even if the defect-free layer is removed by etching or the like to ensure the uniformity of the distribution of recombination centers in the thickness direction, a silicon wafer in which defects are generated at a high density is activated by heating at 200 ° C. or the like. This is because the recombination center that exists exists in addition to Fe-B.
【０００５】本発明は、上記従来技術の問題点に着目
し、酸素析出誘起欠陥等の欠陥を高密度に発生している
シリコンウェーハの鉄濃度を正確にかつ簡便に測定可能
なシリコンウェーハの鉄濃度測定方法を提供することを
目的とする。The present invention focuses on the above-mentioned problems of the prior art, and it is possible to accurately and easily measure the iron concentration of a silicon wafer having a high density of defects such as oxygen precipitation-induced defects. It is intended to provide a method for measuring concentration.
【０００６】[0006]
【課題を解決するための手段】上記目的を達成するた
め、本発明に係るシリコンウェーハの鉄濃度測定方法に
おいて、第１発明は、ｐ型シリコンウェーハにおけるＦ
ｅ−Ｂ結合状態の少数キャリアの拡散長Ｌｂと活性化し
てＦｅint ＋Ｂに解離後急冷した状態の少数キャリアの
拡散長Ｌａとを表面光起電圧法により測定し、測定値に
基づく値の差より鉄濃度を求めるシリコンウェーハの鉄
濃度測定方法において、初めに活性化後急冷した状態の
拡散長Ｌａを測定し、再結合し、再結合状態の拡散長Ｌ
ｂ１を測定し、これら測定値に基づく値の差よりｐ型シ
リコンウェーハの高密度な欠陥層の鉄濃度を求めること
を特徴とする。第２発明は、ｐ型シリコンウェーハにお
けるＦｅ−Ｂ結合状態の少数キャリアの拡散長Ｌｂと活
性化してＦｅint ＋Ｂに解離後急冷した状態の少数キャ
リアの拡散長Ｌａとを表面光起電圧法により測定し、測
定値に基づく値の差より鉄濃度を求めるシリコンウェー
ハの鉄濃度測定方法において、初めに活性化後急冷し、
再結合し、再結合状態の拡散長Ｌｂ１を測定し、再度活
性化後急冷した状態の拡散長Ｌａ１を測定し、これら測
定値に基づく値の差よりｐ型シリコンウェーハの高密度
な欠陥層の鉄濃度を求めることを特徴とする。第３発明
は、第１発明または第２発明において、前記欠陥層が、
無欠陥層をエッチングで除去して露出する欠陥層であ
る。In order to achieve the above-mentioned object, in the method for measuring the iron concentration of a silicon wafer according to the present invention, the first invention is the F concentration in a p-type silicon wafer.
The diffusion length Lb of the minority carrier in the e-B bond state and the diffusion length La of the minority carrier in the activated and dissociated into Fe int + B and then rapidly cooled were measured by the surface photovoltage method, and the difference based on the measured value was used. In the method for measuring the iron concentration of a silicon wafer for determining the iron concentration, first, the diffusion length La in the rapidly cooled state after activation is measured and recombined, and the diffusion length L in the recombined state is measured.
b1 is measured, and the iron concentration of the high-density defect layer of the p-type silicon wafer is obtained from the difference between the values based on these measured values. The second invention is to measure the diffusion length Lb of a minority carrier in a Fe—B bonded state and the diffusion length La of a minority carrier in an activated and dissociated state into Fe int + B and then rapidly cooled in a p-type silicon wafer by a surface photovoltage method. Then, in the iron concentration measuring method of the silicon wafer to obtain the iron concentration from the difference of the value based on the measured value, first after activation, rapidly cooled,
The diffusion length Lb1 in the recombined state and the recombined state is measured, the diffusion length La1 in the rapidly cooled state after activation is measured again, and the difference in the values based on these measurement values is used to measure the high-density defect layer of the p-type silicon wafer. It is characterized in that the iron concentration is obtained. A third invention is the first or second invention, wherein the defect layer is
It is a defect layer exposed by removing the defect-free layer by etching.
【０００７】[0007]
【作用】上記構成による本発明の作用を説明する。高密
度な欠陥層を有するシリコンウェーハの拡散長Ｌａを測
定後、Ｆｅ−Ｂに再結合状態でＳＰＶ法により拡散長Ｌ
ｂ１を測定するので、Ｆｅ−Ｂ以外にも存在する再結合
中心の影響を排除して、鉄およびボロンについての少数
キャリアの拡散長Ｌａ、Ｌｂ１の変化を正確に測定可能
とする。すなわち、欠陥が高密度に発生しているシリコ
ンウェーハでは、Ｆｅ−Ｂ以外に酸素析出誘起欠陥、格
子間のＦｅ等の再結合中心が存在し、２００℃加熱など
により活性化するすると共に、Ｆｅ−Ｂ（不活性状態）
へ再結合する放置後も活性状態にある。したがって、本
発明は、Ｆｅ−Ｂ以外の再結合中心の影響を排除して、
正確な測定が可能となる。これにより得られる（Ｌａ-2
−Ｌｂ１-2）に定数を乗じて鉄濃度を求めるので正確な
値となる。The operation of the present invention having the above construction will be described. After measuring the diffusion length La of a silicon wafer having a high-density defect layer, the diffusion length L is measured by the SPV method in the state of recombining with Fe-B.
Since b1 is measured, the influence of recombination centers existing in addition to Fe—B can be eliminated, and changes in the diffusion lengths La and Lb1 of minority carriers for iron and boron can be accurately measured. That is, in a silicon wafer in which defects are generated at a high density, oxygen precipitation-induced defects and inter-lattice recombination centers such as Fe exist in addition to Fe-B, and they are activated by heating at 200 ° C. -B (inactive state)
It remains active after being left to recombine with. Therefore, the present invention eliminates the effect of recombination centers other than Fe-B,
Accurate measurement is possible. This gives (La -2
An accurate value is obtained because the iron concentration is calculated by multiplying -Lb1 -2 ) by a constant.
【０００８】さらに、拡散長Ｌｂ１の測定後、拡散長Ｌ
ａ１を測定することにより、測定すべき多数のシリコン
ウェーハをまとめて活性化処理後、比較的長時間となる
Ｆｅ−Ｂへの再結合もまとめて行い、その後個々に比較
的短時間となる拡散長Ｌｂ１、Ｌａ１の測定を行うの
で、トータルの測定工数低減に有用である。さらには、
３ステップＩＧ処理等が施され、両端面部に無欠陥層を
形成するシリコンウェーハ等の場合、エッチングにより
無欠陥層を除去して欠陥層を露出させるので、ＳＰＶ法
による測定部分の欠陥分布は均一となり、上記と同様に
正確な測定が可能となる。Further, after measuring the diffusion length Lb1, the diffusion length L
By measuring a1, a large number of silicon wafers to be measured are collectively activated, and then recombined with Fe-B, which takes a relatively long time, are also collectively taken, and then diffusion takes a relatively short time individually. Since the lengths Lb1 and La1 are measured, it is useful for reducing the total number of measurement steps. Moreover,
In the case of a silicon wafer or the like, which is subjected to a three-step IG process or the like to form a defect-free layer on both end surfaces, the defect-free layer is removed by etching to expose the defect layer, so that the defect distribution of the measurement portion by the SPV method is uniform. Therefore, it becomes possible to perform accurate measurement in the same manner as above.
【０００９】[0009]
【実施例】以下に、本発明に係るシリコンウェーハの鉄
濃度測定方法の実施例につき、図面を参照しつつ詳述す
る。図１に本実施例のシリコンウェーハの鉄濃度測定の
手順概要（ステップ２１〜ステップ２７）、図２に図１
の主要ステップでのシリコンウェーハの状態概要を示
す。図２において、（ａ）は鉄濃度測定対象のシリコン
ウェーハ、（ｂ）はエッチングで除去後のシリコンウェ
ーハ、（ｃ）は拡散長Ｌａの測定、（ｄ）は拡散長Ｌｂ
１の測定を示す。Embodiments of the method for measuring the iron concentration of a silicon wafer according to the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an outline of the procedure for measuring the iron concentration of a silicon wafer according to this embodiment (steps 21 to 27), and FIG.
The following is an outline of the state of the silicon wafer in the main steps of. In FIG. 2, (a) is a silicon wafer whose iron concentration is to be measured, (b) is a silicon wafer after being removed by etching, (c) is a measurement of diffusion length La, and (d) is a diffusion length Lb.
1 shows the measurement of 1.
【００１０】まず、ステップ２１および図２（ａ）にお
いて、本実施例の適用対象となるシリコンウェーハ１０
は、ボロンをドーパントとするｐ型のシリコンウェーハ
１０であり、厚さ方向の内部に欠陥層１を有するととも
に、両端面には無欠陥層２が形成されている。この欠陥
層１は、酸素析出誘起欠陥等の欠陥を高密度に、例えば
通常高密度と言われる１０7 ／ｃｍ3 程度以上に有して
いる。このシリコンウェーハ１０は、チョクラルスキー
（ＣＺ）法、あるいは新しいＣＺ法である、磁界下引上
げ（ＭＣＺ）法、リチャージ引上げ（ＲＣＣＺ）法、連
続チャージ引上げ（ＣＣＣＺ）法等により単結晶化され
たインゴットを、スライス等のウェーハ加工により鏡面
研磨ウェーハとした後、３ステップＩＧ処理を施してあ
る。なお、シリコンウェーハ１０は、内部、全体あるい
は一部に高密度な欠陥層１を有するものであれば良いの
で、エピタキシャル層、埋込み層など、半導体デバイス
用に施される構成を有してよく、ＩＧ処理も２ステップ
ＩＧ処理など必要に応じた熱処理条件などで処理されて
よく、さらにはＩＧ処理を施さないものでもよい。ま
た、後述するＳＰＶ法測定により、シリコンウェーハ１
０の欠陥層１の鉄濃度を測定する関係から、欠陥層１の
厚さは測定深さとなる厚さ、通常は２００μｍ程度以上
が好ましく、同様な理由から欠陥層１の抵抗率は０．０
５Ω・ｃｍ程度以上が好ましい。First, in step 21 and FIG. 2A, the silicon wafer 10 to which the present embodiment is applied is applied.
Is a p-type silicon wafer 10 using boron as a dopant, which has a defect layer 1 inside in the thickness direction and defect-free layers 2 formed on both end faces. The defect layer 1 has defects such as oxygen precipitation induced defects at a high density, for example, about 10 7 / cm 3 or more which is usually called high density. The silicon wafer 10 was single-crystallized by the Czochralski (CZ) method or a new CZ method such as a magnetic field pulling (MCZ) method, a recharge pulling (RCCZ) method, and a continuous charge pulling (CCCZ) method. The ingot is processed into a mirror-polished wafer by wafer processing such as slicing, and then subjected to a 3-step IG process. Since the silicon wafer 10 may have the high-density defect layer 1 inside, in whole or in part, it may have a structure such as an epitaxial layer or a buried layer for semiconductor devices, The IG treatment may also be performed under heat treatment conditions, such as a two-step IG treatment, as necessary, and may not be performed. In addition, the silicon wafer 1 is measured by the SPV method described later.
From the relationship of measuring the iron concentration of the defect layer 1 of 0, the thickness of the defect layer 1 is preferably a thickness which is the measurement depth, usually about 200 μm or more. For the same reason, the resistivity of the defect layer 1 is 0.0
It is preferably about 5 Ω · cm or more.
【００１１】次に、ステップ２２および図２（ｂ）に示
すように、欠陥層１を露出させる目的で、シリコンウェ
ーハ１０の無欠陥層２など欠陥層１とは欠陥密度が異な
る部分を化学エッチングにより除去する。確実に欠陥層
１を露出するために、欠陥層１表面の一部までエッチン
グしてもよい。ここで使用されるエッチング液は、フッ
酸と硝酸の混液、またはフッ酸と硝酸に水あるいは酢酸
を加えた混液など、一般的なシリコン用エッチング液が
使用される。このエッチング後のシリコンウェーハ１０
は平滑な鏡面状態が好ましく、フッ酸と硝酸に水あるい
は酢酸を加えた混液で、温度制御と攪拌を行うことが好
ましい。なお、後述するＳＰＶ法による測定は、露出し
た欠陥層１を測定するので、エッチングにて除去する無
欠陥層２は、片面だけでもよい。本ステップの前から、
露出する高密度な欠陥層１を有するシリコンウェーハ１
０の場合は、本ステップを省略してよいことはいうまで
もない。Next, as shown in step 22 and FIG. 2B, in order to expose the defect layer 1, a portion of the silicon wafer 10 having a defect density different from that of the defect layer 1 such as the defect-free layer 2 is chemically etched. To remove. In order to surely expose the defect layer 1, a part of the surface of the defect layer 1 may be etched. As the etching solution used here, a general etching solution for silicon such as a mixed solution of hydrofluoric acid and nitric acid or a mixed solution of hydrofluoric acid and nitric acid with water or acetic acid is used. Silicon wafer 10 after this etching
Is preferably in a smooth mirror-like state, and it is preferable to perform temperature control and stirring with a mixed liquid of hydrofluoric acid and nitric acid to which water or acetic acid is added. Since the measurement by the SPV method described later measures the exposed defect layer 1, the defect-free layer 2 to be removed by etching may be only one side. From before this step,
Silicon wafer 1 having exposed high-density defect layer 1
In the case of 0, it goes without saying that this step may be omitted.
【００１２】次に、ステップ２３において、まず活性化
処理が施される。この活性化処理は、光照射による光学
励起、加熱炉等により、欠陥層１の測定対象となる領域
の鉄ーボロンが解離する状態に活性化する。この解離が
完了あるいは完了と見なせる状態になった後に急冷す
る。すなわち、活性化はＦｅ−Ｂ→Ｆｅint ＋Ｂとなる
解離が生じる状態とするものであり、解離温度となる約
２００℃以上が好ましく、さらにＦｅint の過飽和な固
溶による欠陥層１の表面などへの析出を防止するため、
約２００℃〜約２２０℃がより好ましい。上記解離は、
２００℃で３分程度で完了すると言われており、活性化
状態の保持は、シリコンウェーハ１０の厚さにもよる
が、３０分程度以内が好ましい。この活性化保持後、シ
リコンウェーハ１０をＦｅ−Ｂへの再結合速度が小さい
温度域、一般的には室温程度に急冷する。ステップ２４
および図２（ｃ）に示すように、上記急冷後、欠陥層１
を露出したシリコンウェーハ１０は、短時間内にＳＰＶ
法による測定装置３にて、Ｆｅint ＋Ｂとなる解離状態
１ａの欠陥層１の表面１ｃから、少数キャリアの拡散長
Ｌａが測定される。Next, in step 23, activation processing is first performed. In this activation treatment, iron-boron in the region of the defect layer 1 to be measured is dissociated by optical excitation by light irradiation, a heating furnace, or the like. After this dissociation is completed or can be regarded as completed, it is rapidly cooled. That is, the activation is a state in which dissociation of Fe-B → Fe int + B occurs, and a dissociation temperature of about 200 ° C. or higher is preferable, and further, the surface of the defect layer 1 due to the supersaturated solid solution of Fe int , To prevent precipitation into
More preferred is about 200 ° C to about 220 ° C. The above dissociation is
It is said that the process is completed in about 3 minutes at 200 ° C., and it is preferable to keep the activated state within about 30 minutes, although it depends on the thickness of the silicon wafer 10. After this activation and holding, the silicon wafer 10 is rapidly cooled to a temperature range where the rate of recombination with Fe-B is small, generally about room temperature. Step 24
And, as shown in FIG. 2C, after the rapid cooling, the defect layer 1
The exposed silicon wafer 10 can be used for SPV within a short time.
The diffusion length La of minority carriers is measured from the surface 1c of the defect layer 1 in the dissociated state 1a which becomes Fe int + B by the measuring device 3 by the method.
【００１３】続いて、ステップ２５において、解離した
Ｆｅint ＋ＢがＦｅ−Ｂへ再結合するまでシリコンウェ
ーハ１０を放置する。この放置は、解離温度より低い温
度で保持されれば良いが、室温では１週間程度で、８０
℃では２０分程度で、再結合がほぼ完了すると言われて
おり、室温〜１００℃程度で、２０分〜１週間程度が好
ましく、作業上の効率を考慮して、８０〜１００℃程度
がより好ましい場合もある。ステップ２６および図２
（ｄ）に示すように、放置後、Ｆｅ−Ｂへ再結合したシ
リコンウェーハ１０は、測定装置３で測定可能な温度、
一般的には室温程度で、Ｆｅ−Ｂに再結合状態１ｂの欠
陥層１の表面１ｃから、測定装置３にて少数キャリアの
拡散長Ｌｂ１が測定される。Subsequently, in step 25, the silicon wafer 10 is left until the dissociated Fe int + B is recombined with Fe-B. This standing may be carried out at a temperature lower than the dissociation temperature, but at room temperature it takes about 1 week,
It is said that the recombination is almost completed in about 20 minutes at ℃, room temperature to about 100 ℃, about 20 minutes to 1 week is preferable, and in consideration of work efficiency, about 80 to 100 ℃ is more preferable. Sometimes preferred. Step 26 and FIG.
As shown in (d), after standing, the silicon wafer 10 recombined with Fe-B has a temperature that can be measured by the measuring device 3,
Generally, the diffusion length Lb1 of minority carriers is measured by the measuring device 3 from the surface 1c of the defect layer 1 in the recombination state 1b with Fe-B at about room temperature.
【００１４】次に、ステップ２７において、以上により
測定された拡散長Ｌａ、Ｌｂ１に基づき、欠陥層１の鉄
濃度［Ｆｅ］が求められるが、一般的には、鉄濃度［Ｆ
ｅ］＝定数×（Ｌａ -2−Ｌｂ１-2）となる。さらに、
ＤＬＴＳ法での鉄濃度等を参考にして、鉄濃度［Ｆｅ］
（ｃｍ-3）≒１×１０16（Ｌａ-2−Ｌｂ１-2）が得ら
れ、ここでＬａ、Ｌｂ１の単位はμｍである。Next, in step 27, the iron concentration [Fe] of the defect layer 1 is obtained based on the diffusion lengths La and Lb1 measured as described above. Generally, the iron concentration [F] is obtained.
e] = constant × (La −2 −Lb 1 −2 ). further,
The iron concentration [Fe] with reference to the iron concentration in the DLTS method
(Cm −3 ) ≈1 × 10 16 (La −2 −Lb 1 −2 ) is obtained, where the units of La and Lb 1 are μm.
【００１５】本実施例で測定する拡散長Ｌａ、Ｌｂ１と
従来のＳＰＶ法で測定する拡散長Ｌａ、Ｌｂとの違いを
図３で説明する。すなわち、従来技術では、高密度な欠
陥層１を露出するシリコンウェーハ１０（図２（ｂ）参
照）と仮定した場合、時間Ｔ0 でＦｅ−Ｂ結合状態にお
ける少数キャリアの拡散長Ｌｂを測定し、次に活性化に
よりＦｅint ＋Ｂへ解離した状態（時間Ｔ1 ）で少数キ
ャリアの拡散長Ｌａを測定し、鉄濃度［Ｆｅ］（ｃ
ｍ-3）≒１×１０16（Ｌａ-2−Ｌｂ-2）を求めている。
一方、本発明においては、活性化によりＦｅint ＋Ｂへ
解離した状態（時間Ｔ1 ）で少数キャリアの拡散長Ｌａ
を測定し、放置によりＦｅ−Ｂへ再結合状態（時間
Ｔ2 ）で少数キャリアの拡散長Ｌｂ１を測定し、鉄濃度
［Ｆｅ］（ｃｍ-3）≒１×１０16（Ｌａ-2−Ｌｂ１-2）
を求める。図から明らかなように、測定する拡散長Ｌａ
は同じ値となるが、拡散長Ｌｂと拡散長Ｌｂ１とは異な
る値である。なお、従来技術で、欠陥層と異なる密度の
層、例えば無欠陥層などを表面に形成する状態のシリコ
ンウェーハの場合は、測定される拡散長Ｌａ、Ｌｂには
目的以外の層も含むので、より精度が落ちる。The difference between the diffusion lengths La and Lb1 measured in this embodiment and the diffusion lengths La and Lb measured by the conventional SPV method will be described with reference to FIG. That is, in the prior art, assuming that the silicon wafer 10 (see FIG. 2B) that exposes the high-density defect layer 1 is measured, the diffusion length Lb of the minority carriers in the Fe—B bonded state is measured at time T 0. Then, the diffusion length La of minority carriers is measured in a state of being dissociated into Fe int + B by activation (time T 1 ), and the iron concentration [Fe] (c
m −3 ) ≈1 × 10 16 (La −2 −Lb −2 ) is obtained.
On the other hand, in the present invention, the diffusion length La of minority carriers in the state of being dissociated into Fe int + B by activation (time T 1 )
Was measured, by measuring the diffusion length Lb1 of minority carriers in the recombination state (time T 2) to the Fe-B on standing, the iron concentration [Fe] (cm -3) ≒ 1 × 10 16 (La -2 -Lb1 -2 )
Ask for. As is clear from the figure, the diffusion length La to be measured
Has the same value, but the diffusion length Lb and the diffusion length Lb1 are different values. In the prior art, in the case of a silicon wafer in which a layer having a density different from that of the defect layer, for example, a defect-free layer or the like is formed on the surface, the measured diffusion lengths La and Lb include layers other than the target layer. More accurate.
【００１６】この違いは、従来技術では、２００℃加熱
で、Ｆｅ−Ｂ→Ｆｅint ＋Ｂ以外の変化は無いと仮定し
ていることによる。すなわち、高密度に酸素析出誘起欠
陥等を発生しているシリコンウェーハでは、Ｆｅ−Ｂ以
外の再結合中心（酸素析出誘起欠陥、格子間のＦｅな
ど）が存在し、拡散長Ｌｂ測定時にはＦｅ−Ｂ以外の再
結合中心は不活性であるが、２００℃加熱等の活性化処
理により、このＦｅ−Ｂ以外の再結合中心も活性化す
る。従って、従来技術の拡散長ＬｂにはＦｅ−Ｂ以外の
再結合中心の変化も含んでいる。一方、本発明の拡散長
Ｌｂ１はＦｅ−Ｂのみの変化を測定しており、正確な鉄
濃度が得られる。This difference is based on the assumption that in the prior art, there is no change other than Fe-B → Fe int + B at 200 ° C. heating. That is, recombination centers other than Fe-B (oxygen precipitation-induced defects, interstitial Fe, etc.) exist in a silicon wafer in which oxygen precipitation-induced defects and the like are generated at high density, and Fe- at the time of measuring the diffusion length Lb. Although the recombination centers other than B are inactive, the recombination centers other than Fe-B are also activated by activation treatment such as heating at 200 ° C. Therefore, the diffusion length Lb in the prior art also includes changes in recombination centers other than Fe-B. On the other hand, the diffusion length Lb1 of the present invention measures the change of only Fe-B, and an accurate iron concentration can be obtained.
【００１７】次に、本発明に係わる別の実施例に関し、
図４に示す本実施例のシリコンウェーハの鉄濃度測定の
手順概要（ステップ３１〜ステップ３８）、図２および
図３で説明する。本実施例は、基本的には上述の実施例
と同じであるが、少数キャリアの拡散長Ｌａを時間Ｔ3
で測定する点が異なる。すなわち、化学エッチングによ
り欠陥層１を露出したシリコンウェーハ１０を（ステッ
プ３１、３２）、上述実施例と同様に、ＦｅーＢが解離
する状態に活性化させ、この解離が完了あるいは完了と
見なせる状態になった後に急冷する（ステップ３３）
が、拡散長は測定しない。その後、解離したＦｅint ＋
ＢがＦｅ−Ｂへ再結合するまでシリコンウェーハ１０を
放置し（ステップ３４）、次にステップ３５で上述実施
例と同様に少数キャリアの拡散長Ｌｂ１を測定（時間Ｔ
2 ）する。次に、再度ＦｅーＢが解離する状態に活性化
させ、この解離が完了あるいは完了と見なせる状態にな
った後に急冷し（ステップ３６）、上述実施例と同様に
拡散長Ｌａ１を測定し（ステップ３７）、鉄濃度［Ｆ
ｅ］（ｃｍ-3）≒１×１０16（Ｌａ１-2−Ｌｂ１-2）を
求める（ステップ３８）。なお、拡散長Ｌａ１と上述実
施例の拡散長Ｌａとは、測定する時間は異なるが、値は
同じである。Next, regarding another embodiment according to the present invention,
The outline of the procedure for measuring the iron concentration of the silicon wafer of this embodiment shown in FIG. 4 (steps 31 to 38) will be described with reference to FIGS. 2 and 3. This embodiment is basically the same as the above-mentioned embodiment, but the diffusion length La of the minority carrier is set to the time T 3.
The difference is that it is measured with. That is, the silicon wafer 10 having the defect layer 1 exposed by chemical etching (steps 31 and 32) is activated to a state in which Fe-B is dissociated, as in the above-described embodiment, and the dissociation is completed or can be regarded as completed. Rapidly cools down (step 33)
However, the diffusion length is not measured. After that, dissociated Fe int +
The silicon wafer 10 is allowed to stand until B is recombined with Fe-B (step 34), and then the diffusion length Lb1 of the minority carriers is measured (time T in the same manner as in the above-described embodiment) in step 35.
2 ) Do. Next, Fe-B is activated again to a state where it dissociates, and after this dissociation is complete or can be regarded as complete, it is rapidly cooled (step 36), and the diffusion length La1 is measured in the same manner as in the above-mentioned embodiment (step 36). 37), iron concentration [F
e] (cm −3 ) ≈1 × 10 16 (La1 −2 −Lb1 −2 ) is calculated (step 38). It should be noted that the diffusion length La1 and the diffusion length La of the above-described embodiment have the same values, although the measuring times are different.
【００１８】本実施例にて求められる鉄濃度［Ｆｅ］は
上述実施例と同じであるが、多数のシリコンウェーハ１
０の鉄濃度を測定する場合等に有用である。すなわち、
化学エッチング処理後の多数のシリコンウェーハ１０を
同時に活性化させ、急冷後放置して再結合させ、個々に
拡散長Ｌｂ１および拡散長Ｌａ１を測定する。したがっ
て、活性化処理が一回増加するが、放置して再結合させ
るのが一回で良いので、多数のシリコンウェーハの鉄濃
度を測定する場合は、作業時間が大幅に低減される。The iron concentration [Fe] obtained in this example is the same as that in the above example, but a large number of silicon wafers 1
This is useful when measuring an iron concentration of 0. That is,
A large number of silicon wafers 10 after the chemical etching treatment are simultaneously activated, rapidly cooled and then left to be recombined, and the diffusion length Lb1 and the diffusion length La1 are individually measured. Therefore, the activation process is increased once, but it is sufficient to leave it to be recombined once, so that the working time is greatly reduced when measuring the iron concentration of a large number of silicon wafers.
【００１９】[0019]
【発明の効果】本発明によれば、高密度な欠陥層を有す
るシリコンウェーハを加熱し、Ｆｅ−Ｂを解離後急冷
し、ＳＰＶ法により拡散長Ｌａを測定し、次に解離した
鉄とボロンがＦｅ−Ｂへ再結合後、拡散長Ｌｂ１をＳＰ
Ｖ法により測定する、又は、先に拡散長Ｌｂ１を測定
後、拡散長Ｌａ１を測定し、これらから（Ｌａ-2−Ｌｂ
１-2）又は（Ｌａ１-2−Ｌｂ１-2）を求め、これに定
数、例えば約１×１０16を乗じて鉄濃度を求める。した
がって、Ｆｅ−Ｂ以外の再結合中心の影響を排除して拡
散長を測定するので、正確な鉄濃度が測定される。ま
た、先に拡散長Ｌｂ１を測定する場合には、比較的長時
間を要する放置処理で多数のシリコンウェーハを１度に
処理するので、工数低減が可能となり、コスト低減に寄
与する。さらに、鉄濃度測定方法は、必要に応じてシリ
コンウェーハの無欠陥層等をエッチングで除去して欠陥
層を露出させ、ＳＰＶ法により拡散長を測定するので、
高度な熟練技術を必要とせず、簡便な測定方法である。
以上により、シリコンウェーハの鉄による汚染度を正確
かつ簡便に測定可能とするので、製造工程中あるいは製
造後のシリコンウェーハの清浄度等の品質評価が的確に
かつ容易に行われる。According to the present invention, a silicon wafer having a high-density defect layer is heated, Fe-B is dissociated and then rapidly cooled, the diffusion length La is measured by the SPV method, and then dissociated iron and boron. Diffuses the diffusion length Lb1 after recombining with Fe-B.
It is measured by the V method, or after the diffusion length Lb1 is measured first, the diffusion length La1 is measured, and from these, (La −2 −Lb
1 −2 ) or (La1 −2 −Lb1 −2 ) is obtained, and this is multiplied by a constant, for example, about 1 × 10 16 to obtain the iron concentration. Therefore, the influence of recombination centers other than Fe-B is excluded and the diffusion length is measured, so that an accurate iron concentration is measured. Further, when the diffusion length Lb1 is measured first, a large number of silicon wafers are processed at once by a standing process that requires a relatively long time, so that man-hours can be reduced, which contributes to cost reduction. Further, in the iron concentration measuring method, the defect-free layer or the like of the silicon wafer is removed by etching as necessary to expose the defect layer, and the diffusion length is measured by the SPV method.
It is a simple measurement method that does not require highly skilled technology.
As described above, the degree of iron contamination of the silicon wafer can be measured accurately and easily, so that the quality evaluation such as the cleanliness of the silicon wafer during the manufacturing process or after the manufacturing can be accurately and easily performed.
【図１】本発明に係る実施例のシリコンウェーハの鉄濃
度測定の手順概要を説明する図である。FIG. 1 is a diagram illustrating an outline of a procedure for measuring an iron concentration of a silicon wafer according to an example of the present invention.
【図２】図１の主要ステップでのシリコンウェーハの状
態概要を示す図である。2 is a diagram showing an outline of the state of the silicon wafer in the main steps of FIG.
【図３】本発明に係る実施例で測定する拡散長と従来技
術に係るＳＰＶ法で測定する拡散長との違いを説明する
図である。FIG. 3 is a diagram illustrating a difference between a diffusion length measured by an example according to the present invention and a diffusion length measured by an SPV method according to a conventional technique.
【図４】本発明に係わる別の実施例のシリコンウェーハ
の鉄濃度測定の手順概要を説明する図である。FIG. 4 is a diagram for explaining the outline of the procedure for measuring the iron concentration of a silicon wafer according to another embodiment of the present invention.
【図５】従来技術に係るＳＰＶ法によるシリコンウェー
ハの鉄濃度測定の手順概要を説明する図である。FIG. 5 is a diagram illustrating an outline of a procedure for measuring the iron concentration of a silicon wafer by the SPV method according to the related art.
１ 欠陥層、２ 無欠陥層、３ ＳＰＶ法による測定装
置、１０ シリコンウェーハ、Ｌａ、Ｌａ１、Ｌｂ、Ｌ
ｂ１ 拡散長。1 defect layer, 2 defect free layer, 3 measuring device by SPV method, 10 silicon wafer, La, La1, Lb, L
b1 diffusion length.
Claims (3)
結合状態の少数キャリアの拡散長Ｌｂと活性化してＦｅ
int ＋Ｂに解離後急冷した状態の少数キャリアの拡散長
Ｌａとを表面光起電圧法により測定し、測定値に基づく
値の差より鉄濃度を求めるシリコンウェーハの鉄濃度測
定方法において、初めに活性化後急冷した状態の拡散長
Ｌａを測定し、再結合し、再結合状態の拡散長Ｌｂ１を
測定し、これら測定値に基づく値の差よりｐ型シリコン
ウェーハの高密度な欠陥層の鉄濃度を求めることを特徴
とするシリコンウェーハの鉄濃度測定方法。1. Fe-B in a p-type silicon wafer
Fe is activated by activating the diffusion length Lb of the minority carriers in the bound state.
In the method for measuring the iron concentration of a silicon wafer, the diffusion length La of the minority carriers in the state of being rapidly cooled after dissociation into int + B is measured by the surface photovoltage method, and the iron concentration is determined from the difference between the values based on the measured values. After that, the diffusion length La in the rapidly quenched state is measured, recombined, the diffusion length Lb1 in the recombined state is measured, and the iron concentration in the high-density defect layer of the p-type silicon wafer is determined from the difference between the values based on these measurement values. A method for measuring the iron concentration of a silicon wafer, which is characterized by obtaining.
結合状態の少数キャリアの拡散長Ｌｂと活性化してＦｅ
int ＋Ｂに解離後急冷した状態の少数キャリアの拡散長
Ｌａとを表面光起電圧法により測定し、測定値に基づく
値の差より鉄濃度を求めるシリコンウェーハの鉄濃度測
定方法において、初めに活性化後急冷し、再結合し、再
結合状態の拡散長Ｌｂ１を測定し、再度活性化後急冷し
た状態の拡散長Ｌａ１を測定し、これら測定値に基づく
値の差よりｐ型シリコンウェーハの高密度な欠陥層の鉄
濃度を求めることを特徴とするシリコンウェーハの鉄濃
度測定方法。2. Fe-B in a p-type silicon wafer
Fe is activated by activating the diffusion length Lb of the minority carriers in the bound state.
In the method for measuring the iron concentration of a silicon wafer, the diffusion length La of the minority carriers in the state of being rapidly cooled after dissociation into int + B is measured by the surface photovoltage method, and the iron concentration is determined from the difference between the values based on the measured values. Then, it is rapidly cooled, recombined, the diffusion length Lb1 in the recombined state is measured, the diffusion length La1 in the rapidly cooled state after activation is measured again, and the high density of the p-type silicon wafer is obtained from the difference between the values based on these measurement values. Method for measuring iron concentration in a silicon wafer, characterized in that the iron concentration in a defect layer is obtained.
除去して露出する欠陥層であることを特徴とする請求項
１又は２記載のシリコンウェーハの鉄濃度測定方法。3. The method for measuring iron concentration of a silicon wafer according to claim 1, wherein the defect layer is a defect layer exposed by removing the defect-free layer by etching.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6809194A JPH07249666A (en) | 1994-03-11 | 1994-03-11 | Iron concentration measurement method of silicon wafer |
| TW084109546A TW348289B (en) | 1994-03-11 | 1995-09-12 | Method of measuring a Fe concentration of a silicon wafer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6809194A JPH07249666A (en) | 1994-03-11 | 1994-03-11 | Iron concentration measurement method of silicon wafer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH07249666A true JPH07249666A (en) | 1995-09-26 |
Family
ID=13363726
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6809194A Pending JPH07249666A (en) | 1994-03-11 | 1994-03-11 | Iron concentration measurement method of silicon wafer |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPH07249666A (en) |
| TW (1) | TW348289B (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100386688B1 (en) * | 2000-12-22 | 2003-06-02 | 주식회사 실트론 | A Method for inspection a single crystalline wafer |
| KR20040022999A (en) * | 2002-09-10 | 2004-03-18 | 삼성전자주식회사 | In-line monitoring equipment for wafer contamination and measurement method of wafer contamination |
| KR100499176B1 (en) * | 2002-11-27 | 2005-07-01 | 삼성전자주식회사 | Method for measurement of wafer contamination and apparatus for the same |
| JP2005191315A (en) * | 2003-12-25 | 2005-07-14 | Kyocera Corp | Photoelectric converter and its manufacturing method |
| JP2011054784A (en) * | 2009-09-02 | 2011-03-17 | Sumco Corp | Quantitative analysis limit determination method in iron concentration analysis in boron-doped p-type silicon |
| JP2011233761A (en) * | 2010-04-28 | 2011-11-17 | Sumco Corp | Method for measuring iron concentration in boron-doped p-type silicon, and method for manufacturing the same |
| JP2011243784A (en) * | 2010-05-19 | 2011-12-01 | Sumco Corp | Iron concentration measuring method of boron doped p-type silicon wafer and measuring apparatus, silicon wafer, as well as manufacturing method of silicon wafer |
| JP2012049344A (en) * | 2010-08-27 | 2012-03-08 | Sumco Corp | Quantitative analysis limit determining method for iron concentration analysis in boron-doped p-type silicon |
| JP2012049345A (en) * | 2010-08-27 | 2012-03-08 | Sumco Corp | Iron concentration analytical method in boron dope p-type silicon wafer, analyser for the same, silicon wafer, and method for manufacturing silicon wafer |
-
1994
- 1994-03-11 JP JP6809194A patent/JPH07249666A/en active Pending
-
1995
- 1995-09-12 TW TW084109546A patent/TW348289B/en active
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100386688B1 (en) * | 2000-12-22 | 2003-06-02 | 주식회사 실트론 | A Method for inspection a single crystalline wafer |
| KR20040022999A (en) * | 2002-09-10 | 2004-03-18 | 삼성전자주식회사 | In-line monitoring equipment for wafer contamination and measurement method of wafer contamination |
| KR100499176B1 (en) * | 2002-11-27 | 2005-07-01 | 삼성전자주식회사 | Method for measurement of wafer contamination and apparatus for the same |
| JP2005191315A (en) * | 2003-12-25 | 2005-07-14 | Kyocera Corp | Photoelectric converter and its manufacturing method |
| JP2011054784A (en) * | 2009-09-02 | 2011-03-17 | Sumco Corp | Quantitative analysis limit determination method in iron concentration analysis in boron-doped p-type silicon |
| JP2011233761A (en) * | 2010-04-28 | 2011-11-17 | Sumco Corp | Method for measuring iron concentration in boron-doped p-type silicon, and method for manufacturing the same |
| JP2011243784A (en) * | 2010-05-19 | 2011-12-01 | Sumco Corp | Iron concentration measuring method of boron doped p-type silicon wafer and measuring apparatus, silicon wafer, as well as manufacturing method of silicon wafer |
| JP2012049344A (en) * | 2010-08-27 | 2012-03-08 | Sumco Corp | Quantitative analysis limit determining method for iron concentration analysis in boron-doped p-type silicon |
| JP2012049345A (en) * | 2010-08-27 | 2012-03-08 | Sumco Corp | Iron concentration analytical method in boron dope p-type silicon wafer, analyser for the same, silicon wafer, and method for manufacturing silicon wafer |
| EP2423956A3 (en) * | 2010-08-27 | 2014-04-23 | Sumco Corporation | Method of analyzing iron concentration of boron-doped p-type silicon wafer and method of manufacturing silicon wafer |
Also Published As
| Publication number | Publication date |
|---|---|
| TW348289B (en) | 1998-12-21 |
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