JP3602966B2 - Substrate measuring device - Google Patents

Description

【００４５】
ここで、反射光スペクトルの予測値Ｉｃ（ｋ）と測定値Ｉｍ（ｋ）は、それぞれＮ個の離散的な波長値に関して得られているものと仮定している。なお、一致度の計算式としては、式（１）以外の計算式を用いることも可能である。
【００４６】
測定領域Ｍ１と凹凸部ＵＡとが図６（Ａ−１）に示す位置関係を有する場合には、図６（Ａ−２）に示すようにＧＯＦ値の最大値ＧＯＦｍａｘは「９６０」となる。なお、このように高いＧＯＦ値（１０００に近い値）が得られたときには、絶縁膜の膜厚値を「２１４．５ｎｍ」に等しいと決定することができる。
【００４７】
図６（Ｂ−１）は、測定領域Ｍ１のほぼ５０％の領域に凹凸部ＵＡを含む場合を示している。図６（Ｂ−２）は、図６（Ｂ−１）の状態での反射光スペクトルの測定値Ｉｍと、複数の予測値Ｉｃのうち測定値Ｉｍと最も一致する予測値Ｉｃとを示している。なお、この予測値Ｉｃは、絶縁膜の膜厚値を「１９６．５ｎｍ」と仮定したときの値である。図６（Ｂ−２）に示すように、ウェハＷの凹凸部ＵＡを含む領域を測定領域Ｍ１として反射光スペクトルを測定した場合には、反射光スペクトルの予測値Ｉｃと測定値Ｉｍとはあまり一致しない。このときＧＯＦ値の最大値ＧＯＦｍａｘは「７９０」となっている。
【００４８】
図６（Ｃ−１）は、測定領域Ｍ１内に凹凸部ＵＡのみを含む場合を示している。図６（Ｃ−２）は、図６（Ｃ−１）の状態での反射光スペクトルの測定値Ｉｍと、複数の予測値Ｉｃのうち測定値Ｉｍと最も一致する予測値Ｉｃとを示している。なお、この予測値Ｉｃは、絶縁膜の膜厚値を「１９２．５ｎｍ」と仮定したときの値である。図６（Ｃ−２）に示すように、測定領域Ｍ１内において凹凸部ＵＡを含む領域が増加すると、反射光スペクトルの予測値Ｉｃと測定値Ｉｍとはかなりずれる。このときＧＯＦ値の最大値ＧＯＦｍａｘはさらに小さくなり、「７４０」となっている。
【００４９】
上記のように、反射光スペクトルの複数の予測値Ｉｃと測定値ＩｍとのＧＯＦ値の最大値ＧＯＦｍａｘは、測定領域Ｍ１内に含まれる凹凸部ＵＡの面積によって変化する。すなわち、測定領域Ｍ１内に凹凸部ＵＡを多く含む場合には最大値ＧＯＦｍａｘは小さくなり、凹凸部ＵＡをあまり含まない場合には最大値ＧＯＦｍａｘは大きくなる。したがって、ＧＯＦ値の最大値ＧＯＦｍａｘをウェハの平坦度の指標値として用いれば、測定領域Ｍ１に含まれる凹凸部ＵＡの領域を見積もることができる。
【００５０】
ステップＳ１０４（図３）では、ステップＳ１０３で求められたＧＯＦ値の最大値ＧＯＦｍａｘが所定の閾値以下となるか否かを判断する。本実施例においては、ＧＯＦ値の最大値ＧＯＦｍａｘが「７６０」以下である場合には、膜厚測定部１００の測定対象領域となった測定領域Ｍ１の位置を、ラマン分光測定の測定領域Ｍ２の位置として決定する。なお、本実施例においては、最大値ＧＯＦｍａｘが「７６０」以下となる場合には、測定領域Ｍ１内に凹凸部ＵＡをほぼ８０％以上含んでいる。一方、ＧＯＦ値の最大値ＧＯＦｍａｘが「７６０」を超える場合には、測定領域Ｍ１には、凹凸部ＵＡをあまり含まないので、その測定領域Ｍ１はラマン分光測定の測定領域として不適当と判断される。この場合には、ステップＳ１０１に戻って、次の測定領域Ｍ１’に光スポットを位置決めして再度、一致度を調べる。このようにステップＳ１０１〜Ｓ１０４までの処理を繰り返し行い、ＧＯＦ値の最大値ＧＯＦｍａｘが所定の閾値以下となる測定位置を決定する。
【００５１】
なお、次の測定領域Ｍ１’の位置は、測定領域Ｍ１において得られたＧＯＦ値の最大値ＧＯＦｍａｘに基づいて決定することが好ましい。例えば、得られたＧＯＦ値の最大値ＧＯＦｍａｘから図６（Ａ−１）に示すような状態が予想される場合には、測定領域Ｍ１から光スポットの直径程度離れたところに次の測定領域Ｍ１’を位置決めする。また、図６（Ｂ−１）に示すような状態が予想される場合には、光スポットの半径程度離れたところに次の測定領域Ｍ１’を位置決めする。このようにすれば、ＧＯＦ値の最大値ＧＯＦｍａｘが所定の閾値以下となる測定領域を早く決定することができる。
【００５２】
ステップＳ１０５では、ステップＳ１０４で決定されたＧＯＦ値の最大値ＧＯＦｍａｘが所定の閾値以下となる測定位置において、ラマン分光測定を行う。図７は、ラマン分光測定の測定領域Ｍ２（光スポット）と膜厚測定の測定領域Ｍ１（光スポット）との関係を示す説明図である。図７中、実線で示された領域は、ＧＯＦ値の最大値がほぼ「７６０」となる場合の第１の測定領域Ｍ１を示している。また、破線で示されたラマン分光測定の第２の測定領域Ｍ２は、第１の測定領域Ｍ１とほぼ同じ大きさの領域で設定されている。こうすれば、凹凸部ＵＡを多く含む測定領域Ｍ２をラマン分光測定の測定対象領域とすることができる。
【００５３】
図８は、ラマン分光測定の測定領域Ｍ２と膜厚測定の測定領域Ｍ１との他の関係を示す説明図である。図８中、実線で示された領域は、ＧＯＦ値の最大値がほぼ「７６０」となる場合の測定領域Ｍ１であり、図７に示す測定領域Ｍ１と同じである。一方、破線で示されたラマン分光測定の測定領域Ｍ２は、測定領域Ｍ１より小さく設定されている。このとき、測定領域Ｍ２内には凹凸部ＵＡのみが含まれる。図８に示すように、第２の測定領域Ｍ２を第１の測定領域Ｍ１より小さく設定すれば、より確実に第２の測定領域Ｍ２を決定できるとともに、精度のよい（Ｓ／Ｎ比の高い）測定が可能となる。なお、このような第２の測定領域Ｍ２の大きさの調整は、図１の光出射器２５０と集光レンズ２２とウェハＷとの位置関係を調整することによって行うことができる。
【００５４】
Ｂ．第２実施例：
図９は、本発明の第２実施例としての基板計測装置の構成を示す説明図である。この基板計測装置は、第１実施例の基板計測装置（図１）とほぼ同様の構成であるため詳細な説明は省略する。
【００５５】
本実施例においては、膜厚測定部１００の光出射器１５０とラマン分光測定部２００の光出射器２５０とが平行に並べられており、２つの調整ステージ６２，８０とブラケット６４とを介して支持柱６０取り付けられている。２つの光出射器１５０，２５０の光出射口は距離Ｌだけ離れている。この装置では、ラマン分光測定を行う際には、図に示すようにラマン分光測定用の光出射器２５０からの入射光束が集光レンズ２２の中央付近に入射するように設定される。また、膜厚測定を行う際には、膜厚測定用の光出射器１５０を距離Ｌだけ左方に移動させて、光出射器１５０からの入射光束が集光レンズ２２の中央付近に入射するように設定される。この光出射器１５０，２５０の移動は、調整ステージ８０を水平方向に移動させることによって行われる。
【００５６】
この装置では、上記のように２つの測定系の交換が行われるので、図１に示すハーフミラー２０は備えられていない。このとき、２つの光出射器１５０，２５０から出射される入射光束は、ハーフミラーを通過あるいは反射せずにウェハＷに到達するため、ハーフミラーを使用した場合に比べ、ウェハＷを照射する光の強度を大きくすることが可能である。また、ウェハＷからの反射光束もハーフミラーを透過あるいは反射せずにそれぞれの光出射器１５０，２５０に戻るので、反射光の強度も大きくすることが可能である。したがって、このような構成を採用すれば、より精度のよい（Ｓ／Ｎ比の高い）測定を行うことが可能である。
【００５７】
以上、説明したように、上記実施例においては、第１の測定部として膜厚測定部１００を用いて、ウェハＷ上の第１の測定領域Ｍ１からの反射光スペクトルを測定する。スペクトル分析部１２０は、反射光スペクトルの予測値と測定値との一致度（ＧＯＦ値）を求める。この一致度は、第１の測定領域Ｍ１が凹凸部分をあまり含まない場合には大きい値を示し、凹凸部分を多く含む場合には小さい値を示す。したがって、この一致度を、第１の測定領域Ｍ１の基板の平坦度の指標値として用いれば、第２の測定部の第２の測定領域Ｍ２の位置を容易に決定して、所定の測定を行うことが可能となる。
【００５８】
なお、この発明は上記の実施例や実施形態に限られるものではなく、その要旨を逸脱しない範囲において種々の態様において実施することが可能であり、例えば次のような変形も可能である。
【００５９】
（１）上記実施例においては、ウェハの絶縁膜の膜厚値が未知であるとして、反射光のスペクトルとして複数の膜厚値に応じた複数の予測値Ｉｃを準備しているが、膜厚値が既知であれば反射光スペクトルの予測値は１つのみ準備すればよい。この場合には、１つの予測値に対してＧＯＦ値を求めればよいので、全体としての処理を早く行うことが可能となる。
【００６０】
（２）上記実施例においては、第１の測定部として膜厚測定部１００（図１，図９）を用いて反射光のスペクトルを測定しているが、他の測定装置を用いてもよい。第１の測定部としては、第１の測定領域Ｍ１内の平坦度に関係する値が得られればよく、例えば、反射率を測定する装置を用いてもよい。すなわち、第１の測定領域Ｍ１内に凹凸部分がある場合には、乱反射により反射率が小さくなることが予想されるので、これによっても基板の平坦度を知ることができる。なお、この場合には、測定位置決定部は反射率の大きさによって第２の測定領域Ｍ２の位置を決定すればよい。
【００６１】
（３）上記実施例においては、第２の測定部としてラマン分光測定部２００（図１，図９）を用いているが、他の測定装置を用いてもよい。第２の測定部としては、凹凸部分によって測定領域が制限されるような測定装置を適用することが好ましい。例えば、Ｘ線を用いた銅膜配線パターンの膜厚を測定する装置などを適用することが可能である。なお、第２の測定部によって行われる測定が、ウェハの損傷を伴う場合にも、本発明の基板計測装置を適用できる。
【００６２】
（４）上記実施例においては、スペクトル分析部１２０（図１，図９）は、第２の測定部であるラマン分光測定部２００の測定領域Ｍ２として、ＧＯＦ値の最大値が所定の閾値以下となる凹凸部分を多く含む領域を決定しているが、ＧＯＦ値の最大値が所定の閾値以上となる凹凸部分をあまり含まない領域を第２の測定領域Ｍ２として決定してもよい。すなわち、本発明の測定位置決定部は、第２の測定部の測定に適合するような条件を設定すればよい。
【００６３】
（５）上記実施例では、光スポットを形成するための入射光束がウェハＷにほぼ垂直に入射するものとしていたが、本発明は、入射光束がウェハＷに対して斜めに入射する場合にも適用可能である。
【００６４】
（６）上記実施例において、ハードウェアによって実現されていた構成の一部をソフトウェアに置き換えるようにしてもよく、逆に、ソフトウェアによって実現されていた構成の一部をハードウェアに置き換えるようにしてもよい。
【図面の簡単な説明】
【図１】本発明の第１実施例としての基板計測装置の構成を示す説明図。
【図２】光出射器１５０内における光ファイバの先端部の構成を示す説明図。
【図３】本実施例の基板計測装置の処理手順を示すフローチャート。
【図４】測定対象となる半導体ウェハＷを示す説明図。
【図５】図４の破線で囲まれた領域を拡大して示す説明図。
【図６】測定領域Ｍ１と凹凸部ＵＡとの位置関係、および、その位置関係での反射光スペクトルの測定値Ｉｍを示す説明図。
【図７】ラマン分光測定の測定領域Ｍ２と膜厚測定の測定領域Ｍ１との関係を示す説明図。
【図８】ラマン分光測定の測定領域Ｍ２と膜厚測定の測定領域Ｍ１との他の関係を示す説明図。
【図９】本発明の第２実施例としての基板計測装置の構成を示す説明図。
【符号の説明】
１０…収納容器
１２…ステージ
１４…ガラス板
２０…ハーフミラー
２２…集光レンズ
３６…駆動系コントロール部
５０，６０…支持柱
５２，６２，６８…調整ステージ
５４，６４，６６，７０…ブラケット
８０…調整ステージ
１００…膜厚測定部
１１０…信号処理部
１２０…スペクトル分析部
１２２…ハードディスク装置
１３２…光源部
１３４…分光器
１４１，１４２，２４１，２４２…光ファイバ
１５０，２５０…光出射器
２００…ラマン分光測定部
２３２…光源部
２３４…ラマン分光計
ＣＰ…チップ
Ｍ１，Ｍ２…測定領域
ＳＬ…スクライブライン
ＵＡ…凹凸部
Ｗ…半導体ウェハ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for determining a measurement position on a substrate such as a semiconductor wafer, a glass substrate for a liquid crystal panel, and a photomask substrate for manufacturing a semiconductor based on flatness of a substrate surface, and performing a predetermined measurement at the measurement position. .
[0002]
[Prior art]
In a semiconductor device manufacturing process, various processes are performed on a semiconductor substrate. Patterns, depressions, grooves, and the like are formed on the substrate, and irregularities may occur on the surface thereof. When performing a measurement related to the unevenness of the substrate, it is necessary to perform the measurement while distinguishing between a region including the uneven portion on the substrate and a flat region not including the uneven portion.
[0003]
[Problems to be solved by the invention]
Conventionally, when measuring the unevenness of the substrate, the image processing apparatus has distinguished between a region including the uneven portion and a flat region not including the uneven portion.
[0004]
However, such an image processing apparatus has a problem in that the cost of the measuring apparatus is increased.
[0005]
The present invention has been made in order to solve the above-mentioned problems in the related art, and does not perform complicated image processing and distinguishes and recognizes a region including an uneven portion and a flat region including no uneven portion. It is another object of the present invention to provide a technique capable of determining a measurement position based on the measurement position and performing a predetermined measurement at the measurement position.
[0006]
[Means for Solving the Problems and Their Functions and Effects]
In order to solve at least a part of the above-described problems, an apparatus of the present invention is a substrate measurement apparatus that performs a predetermined measurement on a substrate having a surface with irregularities, and at a first measurement position on the substrate, A first measurement unit that performs a first measurement for obtaining a measurement value related to flatness of a region near the first measurement position, and a flatness obtained according to the measurement value at the first measurement position A measurement position determining unit that determines the first measurement position as a second measurement position suitable for the second measurement when the index value of the second measurement position is within a predetermined range; A second measurement unit for performing the second measurement.
[0007]
The first measurement unit measures a measurement value related to the flatness of the substrate in a region near the first measurement position, and the measurement position determination unit obtains an index value of the flatness from the measurement value. From this index value, it is possible to know how much the uneven portion is included in the area near the first measurement position. This makes it possible to distinguish between the region including the uneven portion and the flat region not including the uneven portion, so that the second measurement position is easily determined based on the index value of the flatness, and the predetermined measurement is performed. It becomes possible.
[0008]
In the substrate measuring device, the region near the second measurement position may be a region including irregularities, and the second measurement performed in the second measurement unit may be a measurement related to the irregularities. Good.
[0009]
Further, in the substrate measuring device, the first measuring unit irradiates the first measurement position with a first light spot, and reflects reflected light from the first light spot at the first measurement position. It is preferable to obtain the measurement value related to the flatness of the neighboring area.
[0010]
The reflected light from the first light spot is related to the flatness of the substrate in a region near the first measurement position. That is, when an uneven portion is included in the vicinity of the first measurement position, the reflected light differs from a flat reflected light that does not include the uneven portion due to irregular reflection by the uneven portion. Therefore, by measuring the reflected light, the flatness of the substrate in the region near the first measurement position can be known.
[0011]
In the substrate measuring device, the first measuring unit is a film thickness measuring unit that performs measurement related to a film thickness value of a thin film formed on the substrate, and the measurement position determining unit is a film thickness value of the thin film. The degree of coincidence between the predicted value of the spectrum of the reflected light predicted from the measured value and the measured value is obtained as the index value, and when the index value is equal to or less than a predetermined threshold, the first measurement position is determined by the second measurement. The position may be determined.
[0012]
If a film thickness measuring unit is used as the first measuring unit, a reflected light spectrum when the substrate is flat can be predicted from the film thickness value of the thin film formed on the substrate. Therefore, if the degree of coincidence between the predicted value of the reflected light spectrum and the measured value is determined as an index value of the flatness, the first measurement position is determined as the second measurement position when the index value is equal to or less than a predetermined threshold value. Can be determined.
[0013]
Further, in the substrate measuring apparatus, the measurement position determining unit prepares in advance a plurality of predicted values of a spectrum of reflected light predicted from a plurality of different film thickness values of the thin film, and a plurality of the predicted values and the It is preferable to determine the maximum value of the degree of coincidence with the measured value as the index value.
[0014]
Even when the film thickness value of the thin film is not known, if a possible range of the film thickness value can be predicted, a plurality of predicted values can be prepared according to the film thickness value in the range. Therefore, even when the film thickness value of the thin film is not known, the flatness of the substrate in the area near the first measurement position is determined by using the maximum value of the coincidence between the plurality of predicted values and the measured value as the index value. You can know.
[0015]
In the substrate measuring device, the second measurement unit may irradiate the second measurement position with a second light spot and analyze reflected light from the second light spot to perform the second measurement. It is preferable that the second light spot is smaller than the first light spot.
[0016]
With this configuration, since the second light spot is included in the first light spot, the measurement by the second measurement unit can be performed with high accuracy.
[0017]
Other aspects of the invention
The present invention includes other aspects as described below. A first aspect is a substrate measurement method for performing a predetermined measurement on a substrate having an uneven surface,
(A) performing, at a first measurement position on the substrate, a first measurement in which a measurement value related to flatness in a region near the first measurement position is obtained;
(B) when the index value of the flatness obtained in accordance with the measurement value at the first measurement position is a value within a predetermined range, the first measurement position is set to a second position suitable for the second measurement. Determining as a second measurement position;
(C) performing the second measurement at the second measurement position;
It is characterized by having.
[0018]
A second aspect is a computer-readable recording medium in which a computer program for causing a computer to realize the functions of each step or each unit of the above invention is recorded.
[0019]
A third aspect is an aspect as a program supply device that supplies, via a communication path, a computer program that causes a computer to realize the functions of each step or each part of the above-described invention. In such an embodiment, the above method and apparatus can be realized by placing the program on a server or the like on a network, downloading the necessary program to a computer via a communication path, and executing the program.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
A. First embodiment:
Hereinafter, embodiments of the present invention will be described based on examples. FIG. 1 is an explanatory diagram showing a configuration of a substrate measuring device as a first embodiment of the present invention. The substrate measuring device includes a storage container 10 for storing a semiconductor wafer W to be measured, a film thickness measuring unit 100 having a function of measuring a film thickness of a thin film (insulating film) formed on the wafer W, A Raman spectrometer 200 having a function of measuring scattered light of the light incident on the wafer W due to the Raman effect is provided. Note that the film thickness measuring unit 100 in the present embodiment corresponds to a first measuring unit of the present invention, and the Raman spectroscopic measuring unit 200 corresponds to a second measuring unit of the present invention.
[0021]
The storage container 10 has a stage 12 movable on a horizontal plane at the bottom thereof. The wafer W is placed on the stage 12. In the vicinity of the center of the upper surface of the storage container 10, a translucent glass plate 14 is fitted. By moving the stage 12 in the horizontal plane, any position on the wafer W can be moved below the glass plate 14.
[0022]
On the storage container 10, two support columns 50 and 60 are erected. A light emitting device 150 of the film thickness measuring section 100 described later is attached to the support column 50 via a first adjustment stage 52 and a bracket 54. A light emitting device 250 of the Raman spectrometer 200 described later is attached to the other support column 60 via a second adjustment stage 62 and a bracket 64. The support column 60 is provided with a half mirror 20 and a condenser lens 22 for guiding the light beams emitted from the two light emitting devices 150 and 250 to the wafer W. The half mirror 20 is mounted on the support column 60 via a bracket 66, and the condenser lens 22 is mounted on the support column 60 via a third adjustment stage 68 and a bracket 70.
[0023]
The first adjustment stage 52 can move the light emitter 150 together with the bracket 54 in the horizontal direction. Similarly, the second and third adjustment stages 62 and 68 can move the light emitting device 250 and the condenser lens 22 in the vertical direction, respectively. Therefore, the positional relationship among the light emitters 150 and 250, the condenser lens 22, and the wafer W can be adjusted well by these adjustment stages 52, 62 and 68.
[0024]
The film thickness measuring unit 100 includes a signal processing unit 110, a light source unit 132, a spectroscope 134, optical fibers 141 and 142, and a light emitting unit 150. The film thickness measuring unit 100 has a function of measuring the film thickness of the insulating film formed on the substrate of the wafer W, and uses the function of the film thickness measurement to indicate the flatness of the surface of the wafer W. It has a function to determine the value.
[0025]
The incident light beam emitted from the light source unit 132 is guided to the light emitting device 150 via the first optical fiber 141. The light emitting device 150 emits the incident light beam toward the half mirror 20 while diverging the light beam at an appropriate angle. After being reflected by the half mirror 20, the incident light flux passes through the condenser lens 22 and the glass plate 14 and is incident on the wafer W almost perpendicularly. The light beam reflected by the wafer W passes through the glass plate 14 and the condenser lens 22, is reflected by the half mirror 20, and returns to the light emitting device 150. The reflected light beam incident on the light emitting device 150 is guided to the spectroscope 134 via the second optical fiber 142.
[0026]
FIG. 2 is an explanatory diagram showing the configuration of the distal end portion of the optical fiber in the light emitting device 150. As shown in FIG. 2, at the tip of the optical fiber, the distribution of the first and second fibers 141 and 142 is grouped into a circle so that the distribution is substantially uniform. With such a configuration, the incident light beam can be emitted from the tip of the light emitting device 150, and the reflected light beam can be made incident. Since an image of the incident light beam emitted from the first optical fiber 141 is formed on the wafer W, the light spot formed on the wafer W has a substantially circular shape.
[0027]
The signal processing unit 110 (FIG. 1) is a computer including a main memory (not shown), a CPU, an input device, and a display device, and a computer program for realizing the function of the spectrum analysis unit 120 in the main memory. Is stored. The signal processing unit 110 is electrically connected to a hard disk device 122 that stores a predicted value Ic of a spectrum of light reflected by the wafer W. The spectrum analyzer 120 analyzes the predicted value Ic of the reflected light spectrum and the measured value of the spectrum of the reflected light flux measured by the spectroscope 134, and determines the film thickness from the degree of coincidence between the predicted value Ic and the measured value. can do. In the present embodiment, as described later, the degree of coincidence is used as an index value of the flatness of the wafer W, and the measurement position in the Raman spectrometer 200 is determined. As can be understood from this description, the spectrum analysis unit 120 corresponds to the measurement position determination unit in the present invention.
[0028]
Further, the signal processing unit 110 is electrically connected to the drive system control unit 36 for driving the stage 12 in the storage container 10 and the three adjustment stages 52, 62, 68. Therefore, by controlling the stage 12 and the three adjustment stages 52, 62, 68 by the drive system control unit 36, the measurement position on the wafer W can be determined, and the optical alignment of the measurement system can be adjusted. Can be.
[0029]
The Raman spectrometer 200 includes a light source 232, a Raman spectrometer 234, optical fibers 241 and 242, and a light emitter 250. The Raman spectrometer 200 has a function of realizing a well-known Raman spectroscopy, and it is possible to measure a stress or the like due to a strain of a crystal by this measurement. Note that, in the present embodiment, the Raman spectroscopic measurement unit 200 sets the uneven portion existing on the wafer W as the measurement target region. The position of the measurement target area is determined based on the index value of the flatness on the wafer W obtained by the spectrum analysis unit 120 as described above.
[0030]
The incident light beam emitted from the light emitting device 250 passes through the half mirror 20 and then passes through the condenser lens 22 and the glass plate 14 to reach the wafer W. The light beam reflected by the wafer W passes through the glass plate 14, the condenser lens 22, and the half mirror 20, and returns to the light emitting device 150. The reflected light beam incident on the light emitting device 250 is guided to the Raman spectrometer 234 via the optical fiber 242, and Raman spectrometry is performed. The distal ends of the optical fibers 241 and 242 in the light emitting device 250 are configured in the same manner as in FIG. Therefore, the light spot formed on the wafer W by the incident light beam emitted from the first fiber 241 is also substantially circular.
[0031]
Note that a computer program for realizing the function of the above-described spectrum analysis unit 120 is provided in a form recorded on a computer-readable recording medium such as a flexible disk or a CD-ROM. The computer reads the computer program from the recording medium and transfers it to an internal storage device or an external storage device. Alternatively, a computer program may be supplied to a computer via a communication path. When implementing the functions of the computer program, the computer program stored in the internal storage device is executed by the microprocessor of the computer. Further, the computer may read a computer program recorded on a recording medium and directly execute the computer program.
[0032]
In this specification, the computer is a concept including a hardware device and an operation system, and means a hardware device that operates under the control of the operation system. In the case where an operation system is unnecessary and a hardware device is operated by an application program alone, the hardware device itself corresponds to a computer. The hardware device includes at least a microprocessor such as a CPU and means for reading a computer program recorded on a recording medium. The computer program includes a program code that causes such a computer to realize the functions of the above-described units. Some of the functions described above may be realized by an operation system instead of the application program.
[0033]
Note that the “recording medium” in the present invention includes a flexible disk, a CD-ROM, a magneto-optical disk, an IC card, a ROM cartridge, a punched card, a printed matter on which a code such as a barcode is printed, a computer internal storage device (RAM And a computer-readable medium such as an external storage device.
[0034]
FIG. 3 is a flowchart illustrating a processing procedure of the substrate measuring apparatus according to the present embodiment. In step S101, the light spot of the incident light beam emitted from the light emitting device 150 of the film thickness measuring unit 100 is positioned at the first measurement position on the wafer W. The positioning of the light spot is performed by the drive system control unit 36 controlling the stage 12.
[0035]
FIG. 4 is an explanatory diagram showing a semiconductor wafer W to be measured. A large number of chips CP are formed on the wafer W, and are divided by scribe lines SL. A predetermined circuit pattern is formed on each chip CP.
[0036]
FIG. 5 is an explanatory diagram showing a region surrounded by a broken line in FIG. 4 in an enlarged manner. As shown in the figure, the chip CP includes an uneven portion UA having unevenness such as a pattern or a depression on the surface. The other area on each chip CP other than the uneven portion UA is a flat area without unevenness. In the present embodiment, a region including the uneven portion UA is a measurement target region for Raman spectrometry in step S105 described later.
[0037]
In step S102, the spectrum of the reflected light from the light spot positioned in step S101 is measured. That is, this light spot becomes a measurement area of the film thickness measurement unit 100.
[0038]
In step S103, the degree of coincidence (GOF value) between the measured value of the reflected light spectrum measured in step S102 and the predicted value Ic of the reflected light spectrum is determined. The predicted value Ic of the reflected light spectrum is determined based on the physical property value (optical constant) of the substrate, the thickness and the physical property value (optical constant) of the thin film. In the present embodiment, a plurality of predicted values Ic corresponding to a plurality of film thickness values are prepared in advance. The range of the plurality of film thickness values is set so as to include at least the range that the film thickness value of the insulating film can take, and the difference between the film thickness values is determined to the extent that sufficient measurement accuracy can be obtained. Note that the range in which the thickness of the insulating film can be taken can be easily estimated usually from the conditions for forming the insulating film.
[0039]
The thickness of the insulating film can be determined from the degree of coincidence between the measured value of the reflected light spectrum and the predicted value Ic of the reflected light spectrum. That is, when the degree of coincidence between the predicted value Ic and the measured value is sufficiently large, the film thickness serving as the basis for calculating the predicted value Ic is determined as the film thickness of the insulating film.
[0040]
In this embodiment, the above-mentioned degree of coincidence is used as an index value of the flatness of the wafer W. That is, when there is an uneven portion in the region within the light spot, the light incident on the wafer W is irregularly reflected by the uneven portion, so that the measured value of the reflected light spectrum includes the uneven portion in the region within the light spot. In the case where there is no reflected light spectrum, the value is different from the predicted value Ic of the reflected light spectrum. Therefore, it is possible to know the flatness of the area in the light spot from the degree of coincidence between the predicted value Ic of the reflected light spectrum and the measured value.
[0041]
FIG. 6 is an explanatory diagram showing the positional relationship between the measurement area M1 and the uneven portion UA, and the measured value Im of the reflected light spectrum in the positional relationship. As shown in FIGS. 6 (A-1), (B-1) and (C-1), the measurement area M1 (light spot) has a substantially circular shape.
[0042]
FIG. 6A-1 shows a case where the measurement area M1 does not include the uneven portion UA at all. FIG. 6A-2 shows the measured value Im of the reflected light spectrum of the light reflected from the measurement area M1 in the state of FIG. 6A-1 and the measured value Im of the plurality of predicted values Ic most closely. Predicted values Ic. The predicted value Ic is a value when the thickness of the insulating film (SiN film) is assumed to be "214.5 nm". As described above, when the reflected light spectrum is measured using a region including only the flat portion of the wafer W as the measurement region M1, a predicted value Ic substantially matching the measured value Im can be obtained.
[0043]
The degree of coincidence (GOF value) between the predicted value Ic of the reflected light spectrum and the measured value Im is obtained by the following equation (1).
[0044]
(Equation 1)

[0045]
Here, it is assumed that the predicted value Ic (k) and the measured value Im (k) of the reflected light spectrum are obtained for each of N discrete wavelength values. Note that a calculation formula other than the formula (1) may be used as a calculation formula of the degree of coincidence.
[0046]
When the measurement region M1 and the uneven portion UA have the positional relationship shown in FIG. 6A-1, the maximum value GOFmax of the GOF value is “960” as shown in FIG. 6A-2. Note that when such a high GOF value (a value close to 1000) is obtained, the thickness of the insulating film can be determined to be equal to "214.5 nm".
[0047]
FIG. 6 (B-1) shows a case where the uneven portion UA is included in almost 50% of the measurement area M1. FIG. 6B-2 shows the measured value Im of the reflected light spectrum in the state of FIG. 6B-1 and the predicted value Ic that most closely matches the measured value Im among the plurality of predicted values Ic. I have. Note that the predicted value Ic is a value when the thickness of the insulating film is assumed to be “196.5 nm”. As shown in FIG. 6B-2, when the reflected light spectrum is measured using the region including the uneven portion UA of the wafer W as the measurement region M1, the predicted value Ic and the measured value Im of the reflected light spectrum are not so large. It does not match. At this time, the maximum value GOFmax of the GOF value is “790”.
[0048]
FIG. 6C-1 shows a case where the measurement area M1 includes only the uneven portion UA. FIG. 6C-2 shows the measured value Im of the reflected light spectrum in the state of FIG. 6C-1 and the predicted value Ic that most closely matches the measured value Im among the plurality of predicted values Ic. I have. Note that the predicted value Ic is a value when the thickness of the insulating film is assumed to be “192.5 nm”. As shown in FIG. 6 (C-2), when the area including the uneven portion UA in the measurement area M1 increases, the predicted value Ic of the reflected light spectrum and the measured value Im deviate considerably. At this time, the maximum value GOFmax of the GOF value is further reduced to “740”.
[0049]
As described above, the maximum value GOFmax of the GOF values of the plurality of predicted values Ic of the reflected light spectrum and the measured value Im changes depending on the area of the uneven portion UA included in the measurement region M1. That is, the maximum value GOFmax is small when the measurement area M1 includes many uneven portions UA, and the maximum value GOFmax is large when the measurement region M1 does not include many uneven portions UA. Therefore, by using the maximum value GOFmax of the GOF value as an index value of the flatness of the wafer, it is possible to estimate the area of the uneven portion UA included in the measurement area M1.
[0050]
In step S104 (FIG. 3), it is determined whether or not the maximum value GOFmax of the GOF value obtained in step S103 is equal to or less than a predetermined threshold. In the present embodiment, when the maximum value GOFmax of the GOF value is equal to or less than “760”, the position of the measurement region M1 which is the measurement target region of the film thickness measurement unit 100 is changed to the measurement region M2 of the Raman spectroscopic measurement. Determine as position. In the present embodiment, when the maximum value GOFmax is equal to or less than “760”, the measurement area M1 includes the uneven portion UA in an amount of about 80% or more. On the other hand, when the maximum value GOFmax of the GOF value exceeds “760”, since the measurement area M1 does not include much the uneven portion UA, the measurement area M1 is determined to be inappropriate as a measurement area for the Raman spectroscopic measurement. You. In this case, returning to step S101, the light spot is positioned in the next measurement area M1 ′, and the degree of coincidence is checked again. In this way, the processing of steps S101 to S104 is repeated to determine the measurement position where the maximum value GOFmax of the GOF value is equal to or less than the predetermined threshold.
[0051]
It is preferable that the position of the next measurement area M1 ′ is determined based on the maximum GOFmax of the GOF values obtained in the measurement area M1. For example, if the state shown in FIG. 6A-1 is expected from the obtained maximum GOF value GOFmax, the next measurement area M1 is located at a distance from the measurement area M1 by about the diameter of the light spot. 'Position. When the state shown in FIG. 6 (B-1) is expected, the next measurement area M1 'is positioned at a position separated by a radius of the light spot. By doing so, it is possible to quickly determine a measurement region where the maximum value GOFmax of the GOF value is equal to or less than the predetermined threshold.
[0052]
In step S105, Raman spectroscopy is performed at a measurement position where the maximum value GOFmax of the GOF value determined in step S104 is equal to or less than a predetermined threshold. FIG. 7 is an explanatory diagram showing the relationship between the measurement area M2 (light spot) for Raman spectrometry and the measurement area M1 (light spot) for film thickness measurement. In FIG. 7, a region indicated by a solid line indicates a first measurement region M1 when the maximum value of the GOF value is substantially “760”. Further, the second measurement area M2 of the Raman spectroscopy measurement indicated by the broken line is set to an area having substantially the same size as the first measurement area M1. In this way, the measurement region M2 including many uneven portions UA can be set as a measurement target region for Raman spectrometry.
[0053]
FIG. 8 is an explanatory diagram showing another relationship between the measurement region M2 for Raman spectroscopy measurement and the measurement region M1 for film thickness measurement. In FIG. 8, a region indicated by a solid line is a measurement region M1 when the maximum value of the GOF value is substantially “760”, and is the same as the measurement region M1 shown in FIG. On the other hand, the measurement area M2 of the Raman spectroscopy indicated by the broken line is set smaller than the measurement area M1. At this time, only the uneven portion UA is included in the measurement region M2. As shown in FIG. 8, if the second measurement region M2 is set smaller than the first measurement region M1, the second measurement region M2 can be determined more reliably, and the accuracy can be improved (the S / N ratio is high). ) Measurement becomes possible. Note that such adjustment of the size of the second measurement region M2 can be performed by adjusting the positional relationship between the light emitting device 250, the condenser lens 22, and the wafer W in FIG.
[0054]
B. Second embodiment:
FIG. 9 is an explanatory diagram showing a configuration of a substrate measuring device as a second embodiment of the present invention. This substrate measuring device has substantially the same configuration as that of the substrate measuring device of the first embodiment (FIG. 1), and a detailed description thereof will be omitted.
[0055]
In the present embodiment, the light emitting device 150 of the film thickness measuring unit 100 and the light emitting device 250 of the Raman spectroscopic measuring unit 200 are arranged in parallel, and via two adjustment stages 62 and 80 and a bracket 64. A support column 60 is attached. The light emitting ports of the two light emitting devices 150 and 250 are separated by a distance L. In this apparatus, when performing Raman spectroscopy measurement, it is set so that the incident light beam from the light emitting device 250 for Raman spectroscopy enters near the center of the condenser lens 22 as shown in the figure. When measuring the film thickness, the light emitting device 150 for measuring the film thickness is moved to the left by the distance L, and the incident light beam from the light emitting device 150 enters near the center of the condenser lens 22. It is set as follows. The light emitting devices 150 and 250 are moved by moving the adjustment stage 80 in the horizontal direction.
[0056]
In this apparatus, since the two measurement systems are exchanged as described above, the half mirror 20 shown in FIG. 1 is not provided. At this time, the incident light beams emitted from the two light emitting devices 150 and 250 reach the wafer W without passing or reflecting through the half mirror, so that the light irradiating the wafer W is compared with the case where the half mirror is used. Can be increased in strength. Also, the reflected light flux from the wafer W returns to the respective light emitting devices 150 and 250 without transmitting or reflecting through the half mirror, so that the intensity of the reflected light can be increased. Therefore, if such a configuration is adopted, more accurate measurement (high S / N ratio) can be performed.
[0057]
As described above, in the above embodiment, the reflected light spectrum from the first measurement region M1 on the wafer W is measured using the film thickness measurement unit 100 as the first measurement unit. The spectrum analyzer 120 calculates the degree of coincidence (GOF value) between the predicted value of the reflected light spectrum and the measured value. This degree of coincidence indicates a large value when the first measurement region M1 does not include many uneven portions, and indicates a small value when the first measurement region M1 includes many uneven portions. Therefore, if this degree of coincidence is used as an index value of the flatness of the substrate in the first measurement area M1, the position of the second measurement area M2 of the second measurement section can be easily determined, and the predetermined measurement can be performed. It is possible to do.
[0058]
It should be noted that the present invention is not limited to the above-described examples and embodiments, and can be carried out in various modes without departing from the scope of the invention, and for example, the following modifications are possible.
[0059]
(1) In the above embodiment, assuming that the thickness of the insulating film of the wafer is unknown, a plurality of predicted values Ic corresponding to the plurality of thicknesses are prepared as the spectrum of the reflected light. If the value is known, only one predicted value of the reflected light spectrum needs to be prepared. In this case, the GOF value may be obtained for one predicted value, so that the entire process can be performed quickly.
[0060]
(2) In the above embodiment, the spectrum of the reflected light is measured using the film thickness measuring unit 100 (FIGS. 1 and 9) as the first measuring unit, but another measuring device may be used. . The first measurement unit only needs to obtain a value related to flatness in the first measurement region M1, and for example, a device that measures reflectance may be used. That is, when there is a concavo-convex portion in the first measurement region M1, the reflectance is expected to be reduced due to irregular reflection, so that the flatness of the substrate can also be known. In this case, the measurement position determination unit may determine the position of the second measurement area M2 based on the magnitude of the reflectance.
[0061]
(3) In the above embodiment, the Raman spectroscopic measurement unit 200 (FIGS. 1 and 9) is used as the second measurement unit, but another measurement device may be used. As the second measuring section, it is preferable to apply a measuring device in which the measuring area is limited by the uneven portion. For example, an apparatus for measuring the thickness of a copper film wiring pattern using X-rays can be applied. Note that the substrate measurement device of the present invention can be applied even when the measurement performed by the second measurement unit involves damage to the wafer.
[0062]
(4) In the above embodiment, the spectrum analyzer 120 (FIGS. 1 and 9) determines that the maximum value of the GOF value is equal to or less than a predetermined threshold as the measurement area M2 of the Raman spectrometer 200 as the second measurement unit. Although the region including many uneven portions is determined, the region that does not include many uneven portions where the maximum value of the GOF value is equal to or more than a predetermined threshold may be determined as the second measurement region M2. That is, the measurement position determination unit of the present invention may set a condition suitable for measurement by the second measurement unit.
[0063]
(5) In the above embodiment, the incident light beam for forming the light spot is assumed to be incident on the wafer W almost perpendicularly. Applicable.
[0064]
(6) In the above embodiment, a part of the configuration realized by hardware may be replaced with software, and conversely, a part of the configuration realized by software may be replaced with hardware. Is also good.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a configuration of a substrate measuring device as a first embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a configuration of an end portion of an optical fiber in a light emitting device 150.
FIG. 3 is a flowchart illustrating a processing procedure of the substrate measuring apparatus according to the embodiment.
FIG. 4 is an explanatory view showing a semiconductor wafer W to be measured.
FIG. 5 is an explanatory diagram showing an enlarged region surrounded by a broken line in FIG. 4;
FIG. 6 is an explanatory diagram showing a positional relationship between the measurement area M1 and the uneven portion UA, and a measured value Im of a reflected light spectrum in the positional relationship.
FIG. 7 is an explanatory diagram showing a relationship between a measurement area M2 for Raman spectrometry and a measurement area M1 for thickness measurement.
FIG. 8 is an explanatory diagram showing another relationship between a measurement area M2 for Raman spectroscopy measurement and a measurement area M1 for film thickness measurement.
FIG. 9 is an explanatory diagram showing a configuration of a substrate measuring device as a second embodiment of the present invention.
[Explanation of symbols]
10. Storage container
12 ... Stage
14 ... Glass plate
20: Half mirror
22 ... Condensing lens
36 ... Drive system control unit
50,60 ... Support column
52, 62, 68 ... Adjustment stage
54, 64, 66, 70 ... bracket
80 ... Adjustment stage
100: film thickness measuring unit
110 ... Signal processing unit
120: Spectrum analysis unit
122: Hard disk drive
132 ... light source
134 ... Spectroscope
141, 142, 241, 242 ... optical fiber
150, 250 ... light emitting device
200 ... Raman spectroscopy unit
232 ... light source
234 ... Raman spectrometer
CP: Chip
M1, M2 ... measurement area
SL… Scribe line
UA: Uneven part
W: Semiconductor wafer

Claims (6)

A substrate measurement device that performs predetermined measurement on a substrate having irregularities on the surface,
A first measurement unit that performs a first measurement in which a measurement value related to flatness of a region near the first measurement position is obtained at a first measurement position on the substrate;
When the index value of the flatness obtained according to the measurement value at the first measurement position becomes a value within a predetermined range, the second measurement suitable for the second measurement is performed at the first measurement position. A measurement position determination unit that determines the position,
A second measurement unit that performs the second measurement at the second measurement position;
A substrate measuring apparatus comprising: The substrate measuring device according to claim 1,
The region near the second measurement position is a region including irregularities,
The substrate measurement device, wherein the second measurement performed by the second measurement unit is a measurement related to the unevenness. The substrate measuring device according to claim 1 or 2,
The first measurement unit irradiates a first light spot on the first measurement position, and reflects light reflected from the first light spot on a flatness of a region near the first measurement position. A substrate measurement device obtained as the measurement value. The substrate measuring device according to claim 3, wherein
The first measurement unit is a film thickness measurement unit that measures a film thickness value of a thin film formed on the substrate,
The measurement position determination unit obtains, as the index value, the degree of coincidence between the predicted value of the spectrum of reflected light predicted from the film thickness value of the thin film and the measured value, and when the index value is equal to or less than a predetermined threshold value A substrate measurement device that determines the first measurement position as the second measurement position. The substrate measuring apparatus according to claim 4, wherein
The measurement position determination unit prepares in advance a plurality of predicted values of the spectrum of the reflected light predicted from a plurality of different film thickness values of the thin film, and sets the maximum degree of coincidence between the plurality of predicted values and the measured value. A substrate measuring device for determining a value as the index value. It is a board | substrate measuring apparatus in any one of Claims 3 thru | or 5, Comprising:
The second measurement unit is a measurement unit that irradiates a second light spot to the second measurement position and performs the second measurement by analyzing reflected light from the second light spot. Yes,
The substrate measuring device, wherein the second light spot is smaller than the first light spot.

Images