JP6947137B2 - Wafer metal contamination evaluation method and wafer manufacturing process management method - Google Patents
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- 229910052751 metal Inorganic materials 0.000 title claims description 163
- 239000002184 metal Substances 0.000 title claims description 157
- 238000011109 contamination Methods 0.000 title claims description 59
- 238000004519 manufacturing process Methods 0.000 title claims description 46
- 238000007726 management method Methods 0.000 title claims description 4
- 238000011156 evaluation Methods 0.000 title description 14
- 235000012431 wafers Nutrition 0.000 claims description 96
- 238000001514 detection method Methods 0.000 claims description 63
- 238000000034 method Methods 0.000 claims description 47
- 238000007689 inspection Methods 0.000 claims description 12
- 238000000921 elemental analysis Methods 0.000 claims description 11
- 238000004611 spectroscopical analysis Methods 0.000 claims description 3
- 238000000550 scanning electron microscopy energy dispersive X-ray spectroscopy Methods 0.000 description 12
- 238000005530 etching Methods 0.000 description 8
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 5
- 238000005498 polishing Methods 0.000 description 5
- 238000012545 processing Methods 0.000 description 5
- 238000007796 conventional method Methods 0.000 description 4
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- 239000002245 particle Substances 0.000 description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- SWXQKHHHCFXQJF-UHFFFAOYSA-N azane;hydrogen peroxide Chemical compound [NH4+].[O-]O SWXQKHHHCFXQJF-UHFFFAOYSA-N 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
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- 238000010894 electron beam technology Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
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- 229910052742 iron Inorganic materials 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
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Description
本発明は、ウェーハの金属汚染の評価方法およびウェーハの製造工程の管理方法に関する。 The present invention relates to a method for evaluating metal contamination of a wafer and a method for controlling a wafer manufacturing process.
一般的に、半導体デバイス用のシリコンウェーハの製造工程は、チョクラルスキー（ＣＺ）法等を使用して単結晶インゴットを育成する単結晶製造工程と、この単結晶インゴットをスライスし、鏡面状に加工するウェーハ加工工程からなる。さらに、付加価値をつけるために、熱処理をするアニール工程やエピタキシャル層を形成するエピタキシャル成長工程を含む場合がある。 Generally, the manufacturing process of a silicon wafer for a semiconductor device is a single crystal manufacturing process in which a single crystal ingot is grown using the Czochralski (CZ) method or the like, and the single crystal ingot is sliced into a mirror surface. It consists of a wafer processing process to be processed. Further, in order to add value, an annealing step of heat treatment and an epitaxial growth step of forming an epitaxial layer may be included.
このようなウェーハ製造工程中には、歩留まりを低下させる金属不純物が混入する場合がある。特に、加工工程では、研磨布や研磨スラリーの交換、洗浄工程ではフィルターの交換に挙げられるようなイベントで発生することが知られている。よって、ウェーハ製造工程中、特に前記イベント後の金属汚染を評価し、管理することは非常に重要である。 During such a wafer manufacturing process, metal impurities that reduce the yield may be mixed. In particular, it is known that it occurs in an event such as replacement of a polishing cloth or a polishing slurry in a processing process and replacement of a filter in a cleaning process. Therefore, it is very important to evaluate and control metal contamination during the wafer manufacturing process, especially after the event.
従来、ウェーハ製造工程中の金属汚染評価方法としては、特許文献１のように、アンモニア−過酸化水素水の溶液（ＳＣ−１溶液）で長時間のエッチング処理を行い、異物検査装置にてエッチング処理後の輝点の増加数から、金属汚染の有無を評価する方法が提案されている。
また、特許文献２には、ウェーハを汚染している金属元素を特定する方法として、ドライエッチング処理後に異物検査装置にて輝点を検出し、走査型電子顕微鏡（Ｓｃａｎｎｉｎｇ Ｅｌｅｃｔｒｏｎ Ｍｉｃｒｏｓｃｏｐｅ。以下、ＳＥＭとも言う）とエネルギー分散型Ｘ線分光分析（Ｅｎｅｒｇｙ Ｄｉｓｐｅｒｓｉｖｅ Ｘ−ｒａｙ ｓｐｅｃｔｒｏｍｅｔｒｙ。以下、ＥＤＸとも言う）にて、輝点の元素分析を行い、金属元素を特定する方法が提案されている。
Conventionally, as a metal contamination evaluation method in a wafer manufacturing process, as in
Further, in
しかし、特許文献１の方法では金属汚染の有無は判定出来ても、ウェーハを汚染している金属元素を特定出来なく、製造工程の改善が難しい。また、特許文献２の方法では、金属元素の特定に留まり、金属汚染の有無を判定する指標がなく、ウェーハの製造工程の管理には不適である。
さらに、特許文献１、２の両手法とも、薬液保管の厳重な管理が求められ、薬液準備や薬液処理に大変手間がかかる。さらに、長時間のエッチング処理が必要なため、結果を得るには人手と時間がかかる。
However, even if the presence or absence of metal contamination can be determined by the method of
Further, both methods of
本発明は上記問題に鑑みてなされたものであり、長時間のエッチング処理が必要なく、ウェーハの金属汚染の有無や金属元素を評価できる方法を提供することを目的とする。 The present invention has been made in view of the above problems, and an object of the present invention is to provide a method capable of evaluating the presence or absence of metal contamination of a wafer and metal elements without the need for long-time etching treatment.
上記目的を達成するために、本発明は、ウェーハの金属汚染の評価方法であって、
被評価ウェーハ表面の輝点を異物検査装置にて検出して輝点数を集計する第１工程と、
該第１工程で検出した被評価ウェーハ表面の輝点の元素分析を走査型電子顕微鏡とエネルギー分散型Ｘ線分光分析にて行い、該元素分析で金属元素が検出された輝点数を集計する第２工程と、
（前記第２工程で集計した輝点数）／（前記第１工程で集計した輝点数）から金属検出率を算出する第３工程と、
前記第３工程で算出した金属検出率が、予め設定した所定の金属検出率を超えた場合に、前記被評価ウェーハに金属汚染が発生していると評価する第４工程とからなることを特徴とするウェーハの金属汚染の評価方法を提供する。
In order to achieve the above object, the present invention is a method for evaluating metal contamination of a wafer.
The first step of detecting the bright spots on the surface of the wafer to be evaluated with a foreign matter inspection device and totaling the number of bright spots,
Elemental analysis of the bright spots on the surface of the wafer to be evaluated detected in the first step is performed by a scanning electron microscope and energy dispersive X-ray spectroscopic analysis, and the number of bright spots in which a metal element is detected in the elemental analysis is totaled. 2 steps and
The third step of calculating the metal detection rate from (the number of bright spots aggregated in the second step) / (the number of bright spots aggregated in the first step), and
When the metal detection rate calculated in the third step exceeds a predetermined metal detection rate set in advance, the fourth step is to evaluate that metal contamination has occurred in the wafer to be evaluated. Provided is a method for evaluating metal contamination of a wafer.
このような本発明のウェーハの金属汚染の評価方法であれば、第３工程で算出した上記金属検出率（全体の金属検出率とも言う）と上記予め設定した所定の金属検出率（全体の金属検出率の規格値とも言う）に基づいて、例えばウェーハ製造工程中における、規格を超えるようなウェーハの金属汚染の有無を判定することができる。また、上記元素分析からウェーハ製造工程中にウェーハを汚染した金属元素を特定することができる。このためウェーハ製造工程における金属汚染の管理ができる。さらに、従来法において必要であったエッチング処理も不要とすることができ、手間がかからず、人手と時間も少なくて済む。 In the method for evaluating metal contamination of a wafer of the present invention, the metal detection rate calculated in the third step (also referred to as the total metal detection rate) and the preset predetermined metal detection rate (total metal) are used. Based on the detection rate (also referred to as the standard value), it is possible to determine, for example, the presence or absence of metal contamination of the wafer exceeding the standard during the wafer manufacturing process. Further, from the above elemental analysis, it is possible to identify the metal element that contaminated the wafer during the wafer manufacturing process. Therefore, metal contamination in the wafer manufacturing process can be controlled. Further, the etching process required in the conventional method can be eliminated, which saves time and effort and requires less manpower and time.
このとき、前記第３工程において、前記第２工程の元素分析で検出した金属元素の種類ごとに個別の金属検出率をさらに算出し、
前記第４工程において、前記被評価ウェーハに金属汚染が発生していると評価された場合に、前記個別の金属検出率から、金属汚染の原因の金属元素の種類を特定することができる。
At this time, in the third step, individual metal detection rates are further calculated for each type of metal element detected in the elemental analysis of the second step.
In the fourth step, when it is evaluated that the wafer to be evaluated has metal contamination, the type of metal element causing the metal contamination can be specified from the individual metal detection rate.
このように、上記のような各金属元素（例えば、Ｎｉ、Ｃｕ、Ｆｅ、Ａｌなど）の個別の金属検出率に着目することで、より具体的に、ウェーハ製造工程中で金属汚染を引き起こした主な原因の金属元素を迅速に特定できる。 In this way, by focusing on the individual metal detection rates of each metal element (for example, Ni, Cu, Fe, Al, etc.) as described above, more specifically, metal contamination was caused in the wafer manufacturing process. The main causative metal element can be quickly identified.
また、本発明は、ウェーハの製造工程の管理方法であって、
上記本発明のウェーハの金属汚染の評価方法により、前記第４工程において、前記被評価ウェーハに金属汚染が発生していると評価した場合に、
該被評価ウェーハの製造履歴調査及び／又はウェーハ製造工程の改善を行うことを特徴とするウェーハの製造工程の管理方法を提供する。
Further, the present invention is a method for controlling a wafer manufacturing process.
When it is evaluated that the wafer to be evaluated has metal contamination in the fourth step by the method for evaluating metal contamination of the wafer of the present invention,
Provided is a method for managing a wafer manufacturing process, which comprises investigating the manufacturing history of the wafer to be evaluated and / or improving the wafer manufacturing process.
このような本発明の管理方法によって、ウェーハへの金属汚染の観点からウェーハ製造工程を管理すれば、汚染原因の金属元素の特定が容易になり、金属汚染が抑制されたウェーハの製造を安定して行うことが出来る。 If the wafer manufacturing process is managed from the viewpoint of metal contamination of the wafer by such a management method of the present invention, it becomes easy to identify the metal element causing the contamination, and the production of the wafer in which the metal contamination is suppressed is stabilized. Can be done.
以上のように、本発明のウェーハの金属汚染の評価方法であれば、従来法のように長時間のエッチング処理を行う必要もなく、ウェーハの金属汚染の有無や金属元素を、簡便に時間をかけずに評価することができる。また、本発明のウェーハの製造工程の管理方法であれば、ウェーハ製造工程中の金属汚染を精度よく、かつ簡便に管理することができる。それにより、金属汚染の抑制されたウェーハを安定して製造することができる。 As described above, according to the method for evaluating metal contamination of a wafer of the present invention, it is not necessary to perform an etching process for a long time as in the conventional method, and the presence or absence of metal contamination on a wafer and metal elements can be easily determined. It can be evaluated without calling. Further, according to the method for controlling the wafer manufacturing process of the present invention, metal contamination during the wafer manufacturing process can be managed accurately and easily. As a result, a wafer in which metal contamination is suppressed can be stably manufactured.
以下、図面を参照して本発明について実施の形態を説明するが、本発明はこれに限定されるものではない。
前述したように、従来法では金属汚染の有無の判定と金属元素の特定の両方を行うことができず、また長時間のエッチング処理を必要とするため、人手、時間、コストがかかるという問題があった。
そこで本発明者らは鋭意検討を重ね、異物検査装置にて、被評価ウェーハ表面の輝点を検出して集計し（第１工程）、検出した輝点を走査型電子顕微鏡とエネルギー分散型Ｘ線分光分析（ＳＥＭ−ＥＤＸ）で元素分析して金属元素が検出された輝点数を集計し（第２工程）、（第２工程で集計した輝点数）／（第１工程で集計した輝点数）から金属検出率を算出し（第３工程）、前記金属検出率とその規格値（管理値）から、ウェーハ製造工程中の金属汚染の有無を評価する（第４工程）方法を見出した。さらには、この評価方法を用いることで、ウェーハの製造工程の管理、より具体的には製造工程における金属汚染管理が出来ることを見出し、本発明の評価方法および管理方法を完成させた。
Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.
As mentioned above, the conventional method cannot both determine the presence or absence of metal contamination and identify the metal element, and requires a long etching process, which causes a problem of labor, time, and cost. there were.
Therefore, the present inventors repeated diligent studies, detected and aggregated the bright spots on the surface of the wafer to be evaluated by the foreign matter inspection device (first step), and the detected bright spots were collected by the scanning electron microscope and the energy dispersive X. The number of bright spots in which metal elements were detected by elemental analysis by line spectroscopic analysis (SEM-EDX) was totaled (second step), (the number of bright spots totaled in the second step) / (the number of bright spots totaled in the first step). ), And a method for evaluating the presence or absence of metal contamination in the wafer manufacturing process (fourth step) was found from the metal detection rate and its standard value (control value). Furthermore, they have found that by using this evaluation method, it is possible to control the manufacturing process of wafers, more specifically, to control metal contamination in the manufacturing process, and completed the evaluation method and management method of the present invention.
図１は本発明のウェーハの金属汚染の評価方法およびウェーハの製造工程の管理方法の一例を示すフローチャートである。
まず、第１工程について説明する。図１のＳ１のように、金属汚染評価用のウェーハ（被評価ウェーハ）の表面を異物検査装置にて検査し、輝点を検出し、その輝点数を集計する。すなわち、輝点の個数と各輝点の座標とを取得する。
異物検査装置としては、ウェーハ表面をレーザー光により走査し、異物からの光散乱強度を測定することで、異物を検出する光散乱方式のパーティクルカウンタ（例えば、ＫＬＡ−Ｔｅｎｃｏｒ社製 ＳｕｒｆＳｃａｎ ＳＰ５など）や、ウェーハ表面からの反射光の差を検出することで異物を検出するコンフォーカル光学系のレーザー顕微鏡（例えばレーザーテック社製 ＭＡＧＩＣＳなど）を用いれば良い。
FIG. 1 is a flowchart showing an example of a method for evaluating metal contamination of a wafer and a method for controlling a wafer manufacturing process according to the present invention.
First, the first step will be described. As shown in S1 of FIG. 1, the surface of the wafer for metal contamination evaluation (evaluated wafer) is inspected by a foreign matter inspection device, bright spots are detected, and the number of bright spots is totaled. That is, the number of bright spots and the coordinates of each bright spot are acquired.
The foreign matter inspection device includes a light scattering type particle counter (for example, SurfScan SP5 manufactured by KLA-Tencor) that detects foreign matter by scanning the surface of the wafer with laser light and measuring the light scattering intensity from the foreign matter. , A laser microscope of a confocal optical system (for example, MAGICS manufactured by Lasertech Co., Ltd.) that detects foreign matter by detecting the difference in reflected light from the wafer surface may be used.
次に、第２工程について説明する。図１のＳ２のように、第１工程のＳ１で取得した座標をもとに輝点のＳＥＭ観察を行い、電子線照射により発生した特性Ｘ線に基づいて、ＥＤＸ分析を行う。続いて、金属元素が検出された輝点数を集計する。 Next, the second step will be described. As shown in S2 of FIG. 1, SEM observation of bright spots is performed based on the coordinates acquired in S1 of the first step, and EDX analysis is performed based on the characteristic X-rays generated by electron beam irradiation. Then, the number of bright spots in which the metal element is detected is totaled.
この時、ＳＥＭ−ＥＤＸのサンプリング数は異物検査装置で得られた全輝点が望ましいが、第１工程におけるＳ１での輝点数が例えば１００００個以上の場合は、領域を限定することでサンプリングする輝点数を減らしても構わない。
より具体的に説明すると、後の工程で第１工程での輝点数と第２工程での輝点数を用いて算出する金属検出率について述べるが、その率を算出するにあたって、ウェーハ全面での輝点数が多すぎる場合は、ウェーハ全面ではなく、領域を適宜限定し、その領域内での輝点に限定して第１工程での輝点数と第２工程での輝点数から金属検出率を算出することができる。なお、算出したこの金属検出率を、さらに後の工程で規格値と比較するが、この規格値についても同様の領域から設定したものとし、同じ領域内について比較できるようにする。
At this time, the sampling number of SEM-EDX is preferably all bright spots obtained by the foreign matter inspection device, but when the number of bright spots in S1 in the first step is, for example, 10,000 or more, sampling is performed by limiting the region. You may reduce the number of bright spots.
More specifically, the metal detection rate calculated by using the number of bright spots in the first step and the number of bright spots in the second step will be described in a later step. If the number of points is too large, the area is appropriately limited instead of the entire surface of the wafer, and the metal detection rate is calculated from the number of bright points in the first step and the number of bright points in the second step by limiting to the bright points in that area. can do. The calculated metal detection rate will be compared with the standard value in a later step, but it is assumed that this standard value is also set from the same region so that the comparison can be performed within the same region.
図２には、ＳＥＭ−ＥＤＸの評価例を示しており、ＳＥＭによる観察図とＥＤＸ分析によるグラフである。グラフの横軸は特性Ｘ線のエネルギーレベル（ｋｅＶ）であり、縦軸は特性Ｘ線の強度（カウント）である。ここではＡｌを含んだ異物（パーティクル）であることが分かる。このように、ＥＤＸ分析により、簡便に異物中の成分を特定することができる。 FIG. 2 shows an evaluation example of SEM-EDX, which is an observation diagram by SEM and a graph by EDX analysis. The horizontal axis of the graph is the energy level (keV) of the characteristic X-ray, and the vertical axis is the intensity (count) of the characteristic X-ray. Here, it can be seen that it is a foreign substance (particle) containing Al. In this way, the components in the foreign substance can be easily identified by the EDX analysis.
続いて、第３工程について説明する。図１のＳ３のように、（ＳＥＭ−ＥＤＸで金属元素が検出された輝点数：すなわち、第２工程で集計した輝点数）／（異物検査装置での輝点数：すなわち、第１工程で集計した輝点数）から金属検出率（全体の金属検出率）を算出する。 Subsequently, the third step will be described. As shown in S3 of FIG. 1, (the number of bright spots where a metal element was detected by SEM-EDX: that is, the number of bright spots aggregated in the second step) / (the number of bright spots in the foreign matter inspection device: that is, the total number of bright spots in the first step). The metal detection rate (total metal detection rate) is calculated from the number of bright spots.
さらに第４工程について説明する。図１のＳ４のようにこの全体の金属検出率と、予め設定した所定の金属検出率（全体の金属検出率の規格値）を比較する。そして、その比較の結果（Ｓ５）、全体の金属検出率が、上記全体の規格値を超えた場合は、図１のＳ６のように金属汚染が発生していると判断する。この予め設定した所定の金属検出率は、出来るだけ小さい方が望ましいが、例えば加工工程での研磨布や研磨スラリーの交換や、洗浄工程でのフィルターの交換等のイベントのない定常状態（通常時とも言う）の金属検出率を採用するなど適宜設定することができる。すなわち、定常状態のウェーハに関して、予め、図１のＳ１−Ｓ３と同様の処理を行って上記規格値を求めておくことができる。 Further, the fourth step will be described. As shown in S4 of FIG. 1, the overall metal detection rate is compared with a preset predetermined metal detection rate (standard value of the overall metal detection rate). Then, as a result of the comparison (S5), when the overall metal detection rate exceeds the above-mentioned overall standard value, it is determined that metal contamination has occurred as shown in S6 of FIG. It is desirable that this preset predetermined metal detection rate be as small as possible, but in a steady state without events such as replacement of polishing pad and polishing slurry in the processing process and replacement of the filter in the cleaning process (normal time). It can be set as appropriate, such as by adopting the metal detection rate of). That is, the standard value can be obtained in advance by performing the same processing as in S1-S3 of FIG. 1 for the wafer in the steady state.
そして、上記のように金属汚染が発生していると判断された場合は、Ｓ７のように、被評価ウェーハの製造履歴調査を行ったり、ウェーハ製造工程へフィードバックし、原因を究明して製造工程の改善をする。この調査と改善を両方行うこともできる。 Then, when it is determined that metal contamination has occurred as described above, as in S7, the manufacturing history of the wafer to be evaluated is investigated, feedback is given to the wafer manufacturing process, the cause is investigated, and the manufacturing process is performed. To improve. Both this research and improvement can be done.
一方、Ｓ３の金属検出率が予め設定した金属検出率を下回った場合（すなわち、全体の金属検出率が規格内の場合）は、Ｓ８のように、金属汚染に関して問題なしと判断し、被評価ウェーハを通常通り次工程へ進めれば良い。 On the other hand, when the metal detection rate of S3 is lower than the preset metal detection rate (that is, when the overall metal detection rate is within the standard), it is judged that there is no problem with metal contamination as in S8, and the evaluation is performed. The wafer may proceed to the next process as usual.
また、特に第３工程においては、その前の工程である第２工程のＳ２のＳＥＭ−ＥＤＸにて複数の金属元素が検出された場合は、上述した全体の金属検出率、言い換えると全ての金属元素に関する金属検出率のほかに、各金属元素の金属検出率（個別の金属検出率）を算出することが望ましい。そして、第４工程において金属汚染発生の評価があった場合には、個別の金属検出率にも着目し、特定の金属元素の検出率が高い場合は、該金属元素がウェーハ製造工程中で金属汚染を引き起こした原因の金属元素と判断出来る。このときの参考として、例えば、単純に各々の金属元素の個別の金属検出率同士の大小を比較して判断しても良いし、あるいは、全体の金属検出率のときと同様に、金属元素の種類ごとに予め定常状態における金属検出率（個別の金属検出率の規格値）を求めて設定しておき、その個別の規格値と、被評価ウェーハにおける実際の個別の金属検出率を比較して判断することができる。これにより、ウェーハの金属汚染の主な原因となる金属元素を速やかに特定でき、工程改善等を迅速に行うことが出来る。 Further, particularly in the third step, when a plurality of metal elements are detected by SEM-EDX in S2 of the second step, which is the previous step, the above-mentioned overall metal detection rate, in other words, all metals. In addition to the metal detection rate for elements, it is desirable to calculate the metal detection rate (individual metal detection rate) for each metal element. Then, when the occurrence of metal contamination is evaluated in the fourth step, attention is also paid to the individual metal detection rate, and when the detection rate of a specific metal element is high, the metal element is a metal in the wafer manufacturing process. It can be judged that it is the metal element that caused the contamination. As a reference at this time, for example, it may be determined by simply comparing the magnitudes of the individual metal detection rates of each metal element, or as in the case of the overall metal detection rate, of the metal element. The metal detection rate (standard value of individual metal detection rate) in the steady state is obtained and set in advance for each type, and the individual standard value is compared with the actual individual metal detection rate of the wafer to be evaluated. You can judge. As a result, the metal element that is the main cause of metal contamination of the wafer can be quickly identified, and the process can be quickly improved.
図３には、一例として異物検査装置による輝点数が８０個の被評価ウェーハのＳＥＭ−ＥＤＸ評価結果を示している。金属輝点数は１２個で、金属検出率は１５．０％と求まり、これは全体の規格値を超えており、金属汚染が発生したと評価された。さらに各金属元素の金属輝点数は、Ａｌが１０個、Ｆｅが１個、Ｎｉが１個で、金属検出率はＡｌが１２．５％、Ｆｅが１．２５％、Ｎｉが１．２５％と求まった。このように、金属検出率１５．０％においてＡｌが１２．５％とその大半を占めており、Ａｌが主原因であることが特定できる。 FIG. 3 shows, as an example, the SEM-EDX evaluation result of the wafer to be evaluated having 80 bright spots by the foreign matter inspection device. The number of metal bright spots was 12, and the metal detection rate was found to be 15.0%, which exceeded the overall standard value, and it was evaluated that metal contamination had occurred. Furthermore, the number of metal bright spots of each metal element is 10 for Al, 1 for Fe, and 1 for Ni, and the metal detection rate is 12.5% for Al, 1.25% for Fe, and 1.25% for Ni. I was asked. As described above, Al accounts for 12.5% and most of the metal detection rate of 15.0%, and it can be identified that Al is the main cause.
以上のように、本発明のウェーハの金属汚染の評価方法により、全体の金属検出率を指標とすることによって規格を超えるようなウェーハの金属汚染を評価でき、かつ、ＳＥＭ−ＥＤＸにより金属元素を特定することができる。しかも、従来法のような長時間のエッチング処理も必要とせずに、簡便に、手間、時間等をかけずに評価することができる。
さらには、金属元素の種類ごとの個別の金属検出率により、ウェーハの金属汚染の主たる原因の金属元素を迅速に特定することができる。
そして、これらの本発明の評価方法を利用したウェーハの製造工程の管理方法であれば、金属汚染を発見しつつ金属元素の種類も特定し、それによって製造工程における金属汚染の原因を迅速かつ容易に特定しやすくなる。ウェーハ製造工程中の金属汚染の管理が可能となり、さらには製造履歴の調査による製造工程の見直しや改善によって金属汚染の抑制された高品質のウェーハを安定して製造することができる。
As described above, according to the method for evaluating the metal contamination of the wafer of the present invention, the metal contamination of the wafer exceeding the standard can be evaluated by using the overall metal detection rate as an index, and the metal element can be evaluated by SEM-EDX. Can be identified. Moreover, the evaluation can be performed easily and without spending time and effort without requiring a long-time etching process as in the conventional method.
Furthermore, the metal element that is the main cause of metal contamination of the wafer can be quickly identified by the individual metal detection rate for each type of metal element.
Then, if the method of controlling the manufacturing process of the wafer using the evaluation method of the present invention is used, the type of the metal element can be specified while discovering the metal contamination, thereby quickly and easily causing the metal contamination in the manufacturing process. It becomes easier to identify. It is possible to control metal contamination during the wafer manufacturing process, and it is possible to stably manufacture high-quality wafers with suppressed metal contamination by reviewing and improving the manufacturing process by investigating the manufacturing history.
以下、本発明を実施例に基づきさらに説明するが、これらの実施例は例示的に示されるもので限定的に解釈されるべきではない。
（実施例）
本発明のウェーハの金属汚染の評価方法およびウェーハ製造工程の管理方法の実施例について説明する。
初めに、全体の金属検出率の規格値（管理値）として用いる所定の金属検出率を算出した。具体的には、イベントがない通常時のウェーハ１００枚（直径３００ｍｍ）を抜き取り、図１のＳ１−Ｓ３と同様の処理を行って上記の全体の規格値を求めておく。まず、光散乱方式のパーティクルカウンタであるＫＬＡ−Ｔｅｎｃｏｒ社製のＳｕｒｆＳｃａｎ ＳＰ５にてウェーハ表面の異物を検査した。続いて、検出された輝点の元素分析をＳＥＭ−ＥＤＸで行い、（ＳＥＭ−ＥＤＸにて金属元素が検出された輝点数）／（異物検査装置での輝点数）から金属検出率を算出したところ、１．５〜３．３％であったため、全体の規格値（所定の金属検出率）は３．３％と設定した。また、各金属元素の個別の金属検出率はＡｌが０．５％〜１．２％、Ｆｅが０．４〜０．８％、Ｎｉが０．６〜１．３％であった。これらより、参考として個別の規格値をＡｌが１．２％、Ｆｅが０．８％、Ｎｉが１．３％とした。全体および個別の金属検出率の規格値を表１にまとめる（通常時の項目参照）。
Hereinafter, the present invention will be further described based on examples, but these examples are exemplified and should not be construed in a limited manner.
(Example)
Examples of the method for evaluating metal contamination of the wafer and the method for controlling the wafer manufacturing process of the present invention will be described.
First, a predetermined metal detection rate to be used as a standard value (control value) of the overall metal detection rate was calculated. Specifically, 100 wafers (diameter 300 mm) in a normal state where there is no event are extracted, and the same processing as in S1-S3 of FIG. 1 is performed to obtain the above-mentioned overall standard value. First, foreign matter on the wafer surface was inspected with a SurfScan SP5 manufactured by KLA-Tencor, which is a light scattering type particle counter. Subsequently, the elemental analysis of the detected bright spots was performed by SEM-EDX, and the metal detection rate was calculated from (the number of bright spots in which the metal element was detected by SEM-EDX) / (the number of bright spots in the foreign matter inspection device). However, since it was 1.5 to 3.3%, the overall standard value (predetermined metal detection rate) was set to 3.3%. The individual metal detection rates of each metal element were 0.5% to 1.2% for Al, 0.4 to 0.8% for Fe, and 0.6 to 1.3% for Ni. From these, as a reference, the individual standard values were set to 1.2% for Al, 0.8% for Fe, and 1.3% for Ni. Table 1 summarizes the standard values for the overall and individual metal detection rates (see the normal items).
次に、ウェーハ製造工程から鏡面研磨後の被評価ウェーハ（直径３００ｍｍ）を１枚抜き取り、上記装置ＳＰ５にてウェーハ表面の異物を検査した。その結果、検出された輝点の数の合計は９７個であった（図１のＳ１）。
続いて、輝点の元素分析をＳＥＭ−ＥＤＸで行い、全金属輝点数は、１９個であり、全体の金属検出率は１９．６％と求まった（図１のＳ２、Ｓ３）。さらに各金属元素の金属輝点数は、Ａｌが１個、Ｆｅが１７個、Ｎｉが１個で、個別の金属検出率はＡｌが１．０％、Ｆｅが１７．５％、Ｎｉが１．０％と求まった。なお、被評価ウェーハに関するこれらの結果についても上記表１にまとめてある（被評価ウェーハの項目参照）。
Next, one wafer to be evaluated (diameter 300 mm) after mirror polishing was extracted from the wafer manufacturing process, and foreign matter on the wafer surface was inspected by the above device SP5. As a result, the total number of bright spots detected was 97 (S1 in FIG. 1).
Subsequently, elemental analysis of the bright spots was performed by SEM-EDX, and the total number of bright spots of the metal was 19, and the total metal detection rate was found to be 19.6% (S2 and S3 in FIG. 1). Furthermore, the number of metal bright spots of each metal element is 1 for Al, 17 for Fe, and 1 for Ni, and the individual metal detection rates are 1.0% for Al, 17.5% for Fe, and 1. It was found to be 0%. These results regarding the wafer to be evaluated are also summarized in Table 1 above (see the item of the wafer to be evaluated).
ここで、被評価ウェーハの金属検出率と所定の金属検出率（全体の規格値）を比較すると、被評価ウェーハの金属検出率（１９．６％）が所定の金属検出率（３．３％）を超えていることが分かり、被評価ウェーハに金属汚染が発生したと判断した。
さらに、検出された金属元素において個別の金属検出率に着目すると、表１からも分かるようにＡｌやＮｉの個別の金属検出率に比べ、Ｆｅの個別の金属検出率が非常に高く、また参考の個別の規格値との比較にしても、Ｆｅのみ規格値を超えている。これらのことから、被評価ウェーハの金属汚染の主な原因はＦｅと判断した。そしてＦｅの汚染が発生する可能性のあるウェーハ製造工程へフィードバックした。
Here, when the metal detection rate of the wafer to be evaluated is compared with the predetermined metal detection rate (overall standard value), the metal detection rate (19.6%) of the wafer to be evaluated is the predetermined metal detection rate (3.3%). ) Was found, and it was judged that metal contamination occurred on the wafer to be evaluated.
Furthermore, focusing on the individual metal detection rates of the detected metal elements, as can be seen from Table 1, the individual metal detection rates of Fe are much higher than the individual metal detection rates of Al and Ni, and for reference. Even when compared with the individual standard values of, only Fe exceeds the standard value. From these facts, it was determined that Fe was the main cause of metal contamination of the wafer to be evaluated. Then, it was fed back to the wafer manufacturing process where Fe contamination may occur.
ウェーハ製造履歴を調査したところ、該被評価ウェーハは洗浄槽フィルターの交換（イベント）後に洗浄されていることが分かった。そこで、該洗浄槽フィルターをフッ化水素酸希釈液で１２時間かけて洗浄した後、新たにウェーハの洗浄を行った。続いて、この新たに洗浄したウェーハを１枚抜き取り、全体の金属検出率を算出したところ、２．１％という、規格値である３．３％以下の値になり、規格内となるウェーハの製造ができるようになった。
このように、本発明の評価方法および管理方法を用いることで、簡便にウェーハ製造工程中の金属汚染管理ができた。
As a result of investigating the wafer manufacturing history, it was found that the wafer to be evaluated was cleaned after the cleaning tank filter was replaced (event). Therefore, the washing tank filter was washed with a hydrofluoric acid diluted solution for 12 hours, and then the wafer was newly washed. Subsequently, one of the newly cleaned wafers was extracted, and the total metal detection rate was calculated. As a result, the value was 2.1%, which is less than the standard value of 3.3%, which is within the standard. It is now possible to manufacture.
As described above, by using the evaluation method and the control method of the present invention, metal contamination control during the wafer manufacturing process can be easily performed.
なお、本発明は、上記実施形態に限定されるものではない。上記実施形態は、例示であり、本発明の特許請求の範囲に記載された技術的思想と実質的に同一な構成を有し、同様な作用効果を奏するものは、いかなるものであっても本発明の技術的範囲に包含される。 The present invention is not limited to the above embodiment. The above embodiment is an example, and any one having substantially the same configuration as the technical idea described in the claims of the present invention and exhibiting the same effect and effect is the present invention. It is included in the technical scope of the invention.
Claims (3)
被評価ウェーハ表面の輝点を異物検査装置にて検出して輝点数を集計する第１工程と、
該第１工程で検出した被評価ウェーハ表面の輝点の元素分析を走査型電子顕微鏡とエネルギー分散型Ｘ線分光分析にて行い、該元素分析で金属元素が検出された輝点数を集計する第２工程と、
（前記第２工程で集計した輝点数）／（前記第１工程で集計した輝点数）から金属検出率を算出する第３工程と、
前記第３工程で算出した金属検出率が、予め設定した所定の金属検出率を超えた場合に、前記被評価ウェーハに金属汚染が発生していると評価する第４工程とからなることを特徴とするウェーハの金属汚染の評価方法。 It is a method for evaluating metal contamination of wafers.
The first step of detecting the bright spots on the surface of the wafer to be evaluated with a foreign matter inspection device and totaling the number of bright spots,
Elemental analysis of the bright spots on the surface of the wafer to be evaluated detected in the first step is performed by a scanning electron microscope and energy dispersive X-ray spectroscopic analysis, and the number of bright spots in which a metal element is detected in the elemental analysis is totaled. 2 steps and
The third step of calculating the metal detection rate from (the number of bright spots aggregated in the second step) / (the number of bright spots aggregated in the first step), and
When the metal detection rate calculated in the third step exceeds a predetermined metal detection rate set in advance, the fourth step is to evaluate that metal contamination has occurred in the wafer to be evaluated. A method for evaluating metal contamination of wafers.
前記第４工程において、前記被評価ウェーハに金属汚染が発生していると評価された場合に、前記個別の金属検出率から、金属汚染の原因の金属元素の種類を特定することを特徴とする請求項１に記載のウェーハの金属汚染の評価方法。 In the third step, individual metal detection rates are further calculated for each type of metal element detected in the elemental analysis of the second step.
In the fourth step, when it is evaluated that the metal contamination is generated in the evaluated wafer, the type of the metal element causing the metal contamination is specified from the individual metal detection rate. The method for evaluating metal contamination of a wafer according to claim 1.
請求項１または請求項２に記載のウェーハの金属汚染の評価方法により、前記第４工程において、前記被評価ウェーハに金属汚染が発生していると評価した場合に、
該被評価ウェーハの製造履歴調査及び／又はウェーハ製造工程の改善を行うことを特徴とするウェーハの製造工程の管理方法。 It is a management method of the wafer manufacturing process.
When it is evaluated that the wafer to be evaluated has metal contamination in the fourth step by the method for evaluating metal contamination of a wafer according to claim 1 or 2.
A method for managing a wafer manufacturing process, which comprises investigating the manufacturing history of the wafer to be evaluated and / or improving the wafer manufacturing process.
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| JP4507157B2 (en) * | 2003-06-17 | 2010-07-21 | 信越半導体株式会社 | Wafer manufacturing process management method |
| JP3876853B2 (en) * | 2003-06-25 | 2007-02-07 | 信越半導体株式会社 | Wafer evaluation method |
| JP4784420B2 (en) * | 2005-11-30 | 2011-10-05 | 株式会社Ｓｕｍｃｏ | Semiconductor substrate quality evaluation method, semiconductor substrate manufacturing method |
| JP4789651B2 (en) * | 2006-02-24 | 2011-10-12 | 株式会社日立ハイテクノロジーズ | Simulation device, simulation program, and simulation method |
| JP6102277B2 (en) * | 2013-01-24 | 2017-03-29 | 株式会社Sumco | Method for evaluating metal contamination of semiconductor wafer and method for manufacturing semiconductor wafer |
| JP6094898B2 (en) * | 2014-05-15 | 2017-03-15 | 信越半導体株式会社 | Contamination assessment method |
| JP6519804B2 (en) * | 2016-04-01 | 2019-05-29 | 住友金属鉱山株式会社 | Method of analyzing the abnormal part of the surface of the laminate |
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