JP2007163417A - Image position measuring method and image position measuring instrument - Google Patents

Image position measuring method and image position measuring instrument Download PDF

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JP2007163417A
JP2007163417A JP2005363292A JP2005363292A JP2007163417A JP 2007163417 A JP2007163417 A JP 2007163417A JP 2005363292 A JP2005363292 A JP 2005363292A JP 2005363292 A JP2005363292 A JP 2005363292A JP 2007163417 A JP2007163417 A JP 2007163417A
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pattern
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Katsuyuki Takahashi
克幸 高橋
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Holon Co Ltd
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Holon Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To generate an image wherein products of a prescribed number of lines before and after a marked line about the plurality of acquired images are repeatedly replaced by the marked line, and capable of measuring the length based on the image to attain the length measurement of high reproducibility, as to an image position measuring method and an image position measuring instrument for measuring a length of a pattern on the image. <P>SOLUTION: This method/instrument has a step for acquiring the plurality of images from the same length measuring objective area, a step for calculating the product of the lines before and after the marked line in the each acquired image, and for repeating the substitution in the marked line to improve image quality, a step for length-measuring a dimension of the measuring objective pattern in the each image improved in the image quality, and a step for determining the dimension of the pattern, based on the length-measured dimension of the pattern of the each image. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、画像上でパターンの測長を行う画像位置測定方法および画像位置測定装置に関するものである。   The present invention relates to an image position measuring method and an image position measuring apparatus for measuring a pattern on an image.

従来、走査電子顕微鏡などでマスクやLSIのパターンの画像を取得し、そのパターンの寸法などを測定する場合、複数枚の画像を取得して総和を算出し、算出した総和の画像中のパターンを測長し、測定値の再現性を高めるようにしていた。   Conventionally, when acquiring an image of a mask or LSI pattern with a scanning electron microscope or the like and measuring the dimension of the pattern, etc., obtain a plurality of images, calculate the sum, and calculate the pattern in the calculated sum image. The length was measured to improve the reproducibility of measured values.

しかし、特に、走査型電子顕微鏡などで取得したマスクやLSIなどのパターンの画像では、上述した複数枚の画像を取得して総和を算出した画像からパターンを測長していたのでは、充分は再現性が得られないという問題があった。   However, in particular, in the case of pattern images such as masks and LSIs acquired with a scanning electron microscope or the like, it is sufficient if the pattern is measured from the image obtained by acquiring a plurality of images and calculating the sum. There was a problem that reproducibility could not be obtained.

本発明は、これらの問題を解決するため、取得した複数毎の画像について注目するラインの所定数本の前後のラインの積を当該注目ラインに置き換えることを繰り返した画像を生成し、当該画像をもとに測長し、より再現性の高い測長を実現することを目的としている。   In order to solve these problems, the present invention generates an image obtained by repeatedly replacing the product of a predetermined number of lines before and after a predetermined number of lines of interest for each of a plurality of acquired images with the line of interest. The purpose is to measure the length based on the original and to achieve length measurement with higher reproducibility.

本発明は、取得した複数毎の画像について注目するラインの所定数本の前後のラインの積を当該注目ラインに置き換えることを繰り返した画像を生成し、当該画像をもとに測長することにより、より再現性の高い測長を実現することが可能となる。   The present invention generates an image by repeatedly replacing the product of a predetermined number of lines before and after the line of interest for each acquired plurality of images with the line of interest, and measures the length based on the image. Therefore, it is possible to realize length measurement with higher reproducibility.

本発明は、取得した複数毎の画像について注目するラインの所定数本の前後のラインの積を当該注目ラインに置き換えることを繰り返した画像を生成し、当該画像をもとに測長し、より再現性の高い測長を実現した。   The present invention generates an image in which the product of a predetermined number of lines before and after a plurality of lines of interest for each acquired plurality of images is replaced with the line of interest, measures the length based on the image, and more Realized highly reproducible length measurement.

図1は、本発明のシステム構成図を示す。
図1において、処理装置1は、プログラムに従い各種処理を行うものであって、ここでは、画像取得手段2、積算出手段3、和算出手段4、測長手段5、比較・決定手段6、画像ファイル7、結果ファイル8、表示装置9、および入力装置10などから構成されるものである。
FIG. 1 shows a system configuration diagram of the present invention.
In FIG. 1, a processing apparatus 1 performs various processes according to a program. Here, an image acquisition means 2, a product calculation means 3, a sum calculation means 4, a length measurement means 5, a comparison / determination means 6, an image The file 7, the result file 8, the display device 9, and the input device 10 are configured.

画像取得手段2は、図示外の走査型電子顕微鏡などから同一視野の複数枚の画像11を取得するものである。   The image acquisition means 2 acquires a plurality of images 11 having the same field of view from a scanning electron microscope (not shown).

積算出手段3は、各画像の注目する走査線(ライン)の前後所定数の走査線の積を算出し、当該注目走査線と置き換えることを繰り返して画質改善するものである。   The product calculation means 3 calculates the product of a predetermined number of scanning lines before and after the scanning line (line) of interest in each image and replaces the scanning line of interest repeatedly to improve the image quality.

和算出手段4は、各画像の注目する走査線の前後所定数の走査線の和を算出し、当該注目走査線と置き換えることを繰り返して画質改善するものである。   The sum calculation means 4 calculates the sum of a predetermined number of scanning lines before and after the scanning line of interest of each image and repeats the replacement with the scanning line of interest to improve the image quality.

測長手段5は,積算出手段3によって画質改善した後の複数の各画像中の測長対象のターンを測長したり、和算出手段3によって画質改善した後の複数の各画像中の測長対象のパターンを測長したりするものである。   The length measuring means 5 measures the length of a length measurement target in each of the plurality of images after the image quality improvement by the product calculation means 3 or the measurement in each of the plurality of images after the image quality improvement by the sum calculation means 3. It measures the pattern of the long object.

比較・決定手段6は、積算出手段3で画質改善された複数の画像中のパターンを測長手段5で測長した寸法の再現誤差(例えばσ、3σ)が、所定の再現誤差の閾値、あるいは和算出手段4で画質改善された複数の画像中のパターンを測長手段5で測長した寸法の再現誤差(例えばσ、3σ)とを比較し、前者が後者よりも小さいときに、前者の寸法を出力したりなどするものである(図2〜図4参照)。   The comparison / determination means 6 includes a dimension reproduction error (for example, σ, 3σ) obtained by measuring the pattern in the plurality of images whose image quality has been improved by the product calculation means 3 by the length measurement means 5, a predetermined reproduction error threshold value, Alternatively, when a pattern in a plurality of images whose image quality has been improved by the sum calculation means 4 is compared with a dimension reproduction error (for example, σ, 3σ) measured by the length measurement means 5, the former is smaller than the latter. Or the like (see FIGS. 2 to 4).

画像ファイル7は、取得した複数の画像11を格納するものである。
結果ファイル8は、画像中のパターンを測長した寸法、再現誤差(例えばσ、3σ)を保存するものである。
The image file 7 stores a plurality of acquired images 11.
The result file 8 stores the dimension obtained by measuring the pattern in the image and the reproduction error (for example, σ, 3σ).

表示装置9は、画像や測長結果などを表示するものである。
入力装置10は、各種指示やデータを入力するものであって、キーボードやマウスなどである。
The display device 9 displays images, measurement results, and the like.
The input device 10 inputs various instructions and data, and is a keyboard or a mouse.

画像11は、走査型電子顕微鏡、透過型電子顕微鏡、あるいは光学顕微鏡などによって生成した測定対象のパターンを含む同一視野から順次取得した複数の画像である。   The image 11 is a plurality of images sequentially acquired from the same field of view including the pattern to be measured generated by a scanning electron microscope, a transmission electron microscope, an optical microscope, or the like.

次に、図2のフローチャートの順番に従い図1の構成の動作を詳細に説明する。
図2は、本発明の動作説明フローチャートを示す。
Next, the operation of the configuration of FIG. 1 will be described in detail according to the order of the flowchart of FIG.
FIG. 2 shows a flowchart for explaining the operation of the present invention.

図2において、S1は、画像を取得する。これは、例えば走査型電子顕微鏡でマスクあるいはLSI中のパターンのある測定対象の同一領域から、例えば30枚の画像(512画素×512画素の画像)を取得し、画像ファイル7に格納し、以降の処理に使えるようにする。尚、画像は、走査型電子顕微鏡でマスクなどから取得した2次電子画像(反射電子画像)に限られず、透過型電子顕微鏡、光学顕微鏡などで同一領域から、例えば30枚の画像を取得してもよい。   In FIG. 2, S1 acquires an image. This is because, for example, 30 images (512 pixels × 512 pixels image) are acquired from the same area of the measurement target having a pattern in the mask or LSI with a scanning electron microscope, and stored in the image file 7. It can be used for processing. The images are not limited to secondary electron images (reflected electron images) acquired from a mask or the like with a scanning electron microscope, and for example, 30 images are acquired from the same region with a transmission electron microscope, an optical microscope, or the like. Also good.

S2は、走査線1本Siに注目し、前後k本(例えば20本)の積を規格化する。これは、後述する図3の(b)に示すように、注目したSi本目のラインの前後の20本について順次積を求め、当該求めた総積を規格化(例えば総積の走査線の最大ピークと、元の走査線の最大ピークとがほぼ等しくなるように規格化)する。ここで、前の走査線に対して、次の走査線をいわば重みとして乗算して積を求めることを所定本数(ここでは、20本)繰り返すことにより、信号の強い部分をより強調した走査線の波形にして画質を改善して後述する偏差3σをより小さくし、複数画像間の測長値の再現性を高めることが可能となる。   S2 pays attention to one scanning line Si, and normalizes the product of k before and after (for example, 20). As shown in FIG. 3B, which will be described later, the product is sequentially obtained for 20 lines before and after the noticed Si-th line, and the obtained total product is normalized (for example, the maximum of the scanning line of the total product). Normalization is performed so that the peak and the maximum peak of the original scanning line are substantially equal. Here, by multiplying the previous scanning line by multiplying the next scanning line as a weight, the product is obtained by repeating a predetermined number (here, 20), the scanning line in which a strong signal portion is further emphasized. It is possible to improve the image quality by reducing the deviation 3σ, which will be described later, to improve the reproducibility of length measurement values between a plurality of images.

S3は、Liとする。これは、S2で総積を求めて規格化した後の走査線を、元の走査線と置き換える。   S3 is Li. This replaces the original scan line with the scan line after normalization by obtaining the total product in S2.

S4は、終わりか判別する。これは、1つの画像について、全ての走査線(あるいは画像中の測定対象のパターンが存在する領域内の走査線)についてS2、S3を実行したか判別する。YESの場合には、S5に進む。NOの場合には、次の走査線についてS2、S3を繰り返す。   In S4, it is determined whether or not the end. This determines whether or not S2 and S3 have been executed for all scanning lines (or scanning lines in an area where the pattern to be measured in the image exists) for one image. If YES, the process proceeds to S5. In the case of NO, S2 and S3 are repeated for the next scanning line.

以上のS2〜S4のYESによって、画像中の走査線について前後所定本数の総積を求めて規格化し元の走査線を置き換えることを繰り返し、画質を改善した画像を生成することが可能となる(図3の(b)参照)。   With the above YES in S2 to S4, it is possible to generate an image with improved image quality by repeatedly obtaining and normalizing the total number of scanning lines in the image and normalizing and replacing the original scanning line ( (See (b) of FIG. 3).

S5は、最小二乗法でエッジを決定する。これは、S2〜S4のYESで画像中の注目する走査線の前後所定本数の走査線の総積を求めて規格化して画質を改善した画像について、当該画像中のパターンのエッジの点を走査線毎に求め、当該求めた全てのエッジの点について最小二乗法で直線近似した直線(パターンのエッジ)を決定する(図3の(c)の直線を決定する)。   In S5, the edge is determined by the least square method. This is because the edge of the pattern in the image is scanned for an image whose quality has been improved by obtaining the total number of scanning lines of a predetermined number before and after the scanning line of interest in the image in S2 to S4. For each line, a straight line (pattern edge) that is linearly approximated by the least square method is determined for all the obtained edge points (the straight line in FIG. 3C is determined).

S6は、S2〜S5を30回繰り返す。これは、S2〜S5について、S1で取得した画像の枚数、ここでは、30枚に相当する30回繰り返し、各画像についてそれぞれ最小二乗法で直線近似した線分(パターンのエッジ)を決定する。   S6 repeats S2 to S5 30 times. This is repeated for S2 to S5, the number of images acquired in S1, 30 times corresponding to 30 in this case, and line segments (pattern edges) that are linearly approximated by the least square method are determined for each image.

S7は、両端エッジを基に寸法を計測する。これは、S5で決定した画像中のパターンのエッジ(図3の(c)の最小二乗法で直線近似した直線)の寸法(距離)X1(〜Xn)を計測する。   In S7, the dimensions are measured based on both end edges. This measures the dimension (distance) X1 (˜Xn) of the edge of the pattern in the image determined in S5 (straight line approximated by the least square method in FIG. 3C).

S8は、寸法値の3σを算出する。これは、S7で各画像でエッジの寸法をX1〜Xnとそれぞれ算出したので、当該算出した寸法X1〜Xnをもとに、公知の偏差3σ(再現誤差)を算出する(図4参照)。   In S8, the dimension value 3σ is calculated. In S7, since the edge dimensions are calculated as X1 to Xn in each image in S7, a known deviation 3σ (reproduction error) is calculated based on the calculated dimensions X1 to Xn (see FIG. 4).

以上のS2からS8によって、各画像中の注目する走査線の前後所定本数の走査線の総積を求めて規格化した後に元の走査線を置き換えることを繰り返し、画質の改善した画像を順次生成し、当該生成した画像中のパターンのエッジの点を算出して最小二乗法により直線近似した線分(エッジ)を求め、当該線分(エッジ)の寸法(間隔)をX1〜Xnとして順次測長すると共にこれら寸法X1〜Xnの偏差3σ(再現誤差)を算出することが可能となる。   Through steps S2 to S8, after obtaining and normalizing the total number of scanning lines of a predetermined number before and after the scanning line of interest in each image, the original scanning lines are repeatedly replaced to sequentially generate images with improved image quality. Then, the edge point of the pattern in the generated image is calculated to obtain a line segment (edge) that is linearly approximated by the least square method, and the dimensions (intervals) of the line segment (edge) are sequentially measured as X1 to Xn. It becomes possible to calculate the deviation 3σ (reproduction error) of these dimensions X1 to Xn as the length increases.

同様にして、S12からS18によって、和の場合の寸法X1〜Xnおよびその偏差3σ(再現誤差)を算出する。以下説明する。   Similarly, the dimensions X1 to Xn and the deviation 3σ (reproduction error) in the case of sum are calculated from S12 to S18. This will be described below.

S12は、走査線1本Siに注目し、前後k本(例えば20本)の和を規格化する。これは、後述する図3の(b)に示すように、注目したSi本目のラインの前後の20本について順次和を求め、当該求めた総和を規格化(例えば総和した走査線の数で除算して規格化)する。   S12 focuses on one scanning line Si and normalizes the sum of front and rear k lines (for example, 20 lines). As shown in FIG. 3B, which will be described later, the sum is sequentially obtained for 20 lines before and after the noticed Si-th line, and the obtained sum is normalized (for example, divided by the total number of scanning lines). Standardize).

S23は、Liとする。これは、S22で総和を求めて規格化した後の走査線を、元の走査線と置き換える。   S23 is Li. This replaces the original scanning line with the scanning line after normalization by obtaining the sum in S22.

S14は、終わりか判別する。これは、1つの画像について、全ての走査線についてS12、S13を実行したか判別する。YESの場合には、S15に進む。NOの場合には、次の走査線についてS12、S13を繰り返す。   In S14, it is determined whether the process is over. This determines whether S12 and S13 have been executed for all scanning lines for one image. If YES, the process proceeds to S15. In the case of NO, S12 and S13 are repeated for the next scanning line.

以上のS12〜S14のYESによって、画像中の走査線について前後所定本数の総和を求めて規格化し元の走査線を置き換えることを繰り返し、画質を改善した画像を生成することが可能となる(図3の(b)参照)。   With the above YES in S12 to S14, it is possible to generate an image with improved image quality by repeatedly obtaining and summing a predetermined number of scanning lines in the image and normalizing and replacing the original scanning lines (FIG. 3 (b)).

S15は、最小二乗法でエッジを決定する。これは、S12〜S14のYESで画像中の注目する走査線の前後所定本数の走査線の総和を求めて規格化して画質を改善した画像について、当該画像中のパターンのエッジの点を走査線毎に求め、当該求めた全てのエッジの点について最小二乗法で直線近似した直線を決定する(図3の(c)の直線を決定する)。   In S15, the edge is determined by the least square method. This is because, in S12 to S14 YES, with respect to an image whose image quality is improved by obtaining the sum of a predetermined number of scanning lines before and after the scanning line of interest in the image and improving the image quality, the point of the edge of the pattern in the image is scanned. A straight line that is linearly approximated by the least square method for all the obtained edge points is determined (a straight line of (c) in FIG. 3 is determined).

S16は、S12〜S15を30回繰り返す。これは、S12〜S15について、S1で取得した画像の枚数、ここでは、30枚に相当する30回繰り返し、各画像についてそれぞれ最小二乗法で直線近似した線分(パターンのエッジ)を決定する。   In S16, S12 to S15 are repeated 30 times. For S12 to S15, the number of images acquired in S1, here, 30 times corresponding to 30 is repeated, and a line segment (pattern edge) that is linearly approximated by the least square method is determined for each image.

S17は、両端エッジを基に寸法を計測する。これは、S15で決定した画像中のパターンのエッジ(図3の(c)の最小二乗法で直線近似した直線)の寸法(距離)X1(〜Xn)を計測する。   In S17, the dimensions are measured based on both end edges. This measures the dimension (distance) X1 (˜Xn) of the edge of the pattern in the image determined in S15 (straight line approximated by the least square method in FIG. 3C).

S18は、寸法値の3σを算出する。これは、S71で各画像でエッジの寸法をX1〜Xnとそれぞれ算出したので、当該算出した寸法X1〜Xnをもとに、公知の偏差3σ(再現誤差率)を算出する(図4参照)。   In S18, the dimension value 3σ is calculated. This is because the edge dimensions X1 to Xn are calculated for each image in S71, and a known deviation 3σ (reproduction error rate) is calculated based on the calculated dimensions X1 to Xn (see FIG. 4). .

以上のS12からS18によって、各画像中の注目する走査線の前後所定本数の走査線の総和を求めて規格化した後に元の走査線を置き換えることを繰り返し、画質の改善した画像を順次生成し、当該生成した画像中のパターンのエッジの点を算出して最小二乗法により直線近似した線分(エッジ)を求め、当該線分(エッジ)の寸法(間隔)をX1〜Xnとして順次測長すると共にこれら寸法X1〜Xnの偏差3σ(再現誤差率)を算出することが可能となる。   Through S12 to S18 described above, after obtaining and normalizing the sum of a predetermined number of scanning lines before and after the scanning line of interest in each image, the original scanning lines are repeatedly replaced to sequentially generate images with improved image quality. Then, the edge point of the pattern in the generated image is calculated to obtain a line segment (edge) linearly approximated by the least square method, and the length (interval) of the line segment (edge) is sequentially measured as X1 to Xn. In addition, the deviation 3σ (reproduction error rate) of these dimensions X1 to Xn can be calculated.

S21は、比較する。これは、S2から8で算出した積の場合の偏差3σと、基準値あるいはS12からS18で算出した和の場合の偏差3σを比較する。   S21 compares. This compares the deviation 3σ for the product calculated from S2 to 8 with the deviation 3σ for the sum calculated from the reference value or S12 to S18.

S22は、3σの小さい方に決定する。
S23は、決定した方の測定値を出力する。これらS22、S23は、S21で比較した結果、S2からS8で算出した積の場合の偏差3σ(再現誤差)が基準値あるいはS12からS18で算出した和の場合の偏差3σ(再現誤差)よりも小さいときには、小さい方の当該S2からS8で算出した積の場合の測定値X1〜Xn(更に、平均値Xa)を出力する。一方、S12からS18で算出した和の場合の偏差3σ(再現誤差)がS2からS8で算出した積の場合の偏差3σ(再現誤差)よりも小さいときには、小さい方の当該S12からS18で算出した和の場合の測定値X1〜Xn(更に、平均値Xa)を出力する。
S22 is determined to be the smaller of 3σ.
S23 outputs the measured value of the determined one. As a result of the comparison in S21, the deviation 3σ (reproduction error) in the case of the product calculated in S2 to S8 is greater than the deviation 3σ (reproduction error) in the case of the sum calculated in S12 to S18. When the value is smaller, measurement values X1 to Xn (further, average value Xa) in the case of the product calculated in the smaller S2 to S8 are output. On the other hand, when the deviation 3σ (reproduction error) in the sum calculated in S12 to S18 is smaller than the deviation 3σ (reproduction error) in the product calculated in S2 to S8, the smaller one is calculated in S12 to S18. Measurement values X1 to Xn (in addition, average value Xa) in the case of sum are output.

以上によって、複数の画像について各画像中のある走査線に注目してその前後の所定本数の走査線の総積を求めて規格化して元の走査線を置き換えることを繰り返し、画質を改善した画像を順次生成、および各画像中のある走査線に注目してその前後の所定本数の走査線の総和を求めて規格化して元の走査線を置き換えることを繰り返し、画質を改善した画像を順次生成した後、画質を改善した後の積および和の画像について測長対象のパターンのエッジの点をそれぞれ求め、これらの点をもとに最小二乗法により直線近似した線分(パターンのエッジ)を求めてその寸法(距離)X1〜Xnを順次それぞれ算出し、これら両者の寸法X1〜Xnについて偏差3σ(再現誤差率)をそれぞれ求め、偏差3σの小さい方の寸法X1〜Xnおよび平均Xaを出力することにより、より再現性の高い寸法を出力することが可能となる。   As described above, with regard to a plurality of images, paying attention to a certain scanning line in each image, obtaining a total product of a predetermined number of scanning lines before and after that, normalizing, and repeatedly replacing the original scanning line, thereby improving the image quality , And then repeatedly generate the image by improving the image quality by repeating the normal scan by replacing the original scan line by obtaining the total number of scan lines before and after focusing on a scan line in each image. After that, the edge points of the pattern to be measured are obtained for the product and sum images after improving the image quality, and line segments (pattern edges) that are linearly approximated by the least square method based on these points are obtained. Then, the dimensions (distances) X1 to Xn are sequentially calculated, the deviation 3σ (reproduction error rate) is obtained for each of these dimensions X1 to Xn, and the smaller dimension X1 to Xn and the flatness of the smaller deviation 3σ are obtained. By outputting the average Xa, it becomes possible to output dimensions with higher reproducibility.

実験では、走査型電子顕微鏡で生成した30枚の画像について上記積の場合と、上記和の場合とを比較して、上記積の場合の方が偏差3σで約26%良い寸法X1〜Xnが得られた。   In the experiment, the above product and the above sum were compared for 30 images generated by a scanning electron microscope. In the case of the above product, the dimensions X1 to Xn were better by about 26% with a deviation 3σ. Obtained.

図3は、本発明の説明図(手順)を示す。
図3の(a)は、画像を取得する例を示す。これは、例えば走査型電子顕微鏡でパターンを細く絞った電子線ビームで走査(ここでは、1走査線が512画素相当で走査し、全体の走査線数が512本で走査)し、そのときに発生した2次電子(あるいは反射電子)を検出して生成した画像を順次取得する様子を示す。順次取得した画像(ここでは、同一視野の順次取得した30枚の画像)は、図1の画像ファイル7に格納する。
FIG. 3 is an explanatory diagram (procedure) of the present invention.
FIG. 3A shows an example of acquiring an image. For example, this is performed by scanning with an electron beam with a finely narrowed pattern with a scanning electron microscope (here, one scanning line is scanned with 512 pixels and the total number of scanning lines is 512). A state in which images generated by detecting generated secondary electrons (or reflected electrons) are sequentially obtained will be described. The sequentially acquired images (here, 30 images sequentially acquired from the same field of view) are stored in the image file 7 of FIG.

図3の(b)は、走査波形を取得する。ここで、左側の走査波形は、図3の(a)で図1の画像ファイル7に格納した画像から走査波形(横方向を走査線方向(512画素相当)、縦軸をそのときの明るさとした走査波形)を取得する。そして、左側の走査波形のある走査波形に注目し、その前後所定本数(例では、20本の走査線)を順次積の演算あるいは和の演算を行い、更に、正規化した後に右側に示すように、元の走査線を置き換える態様で格納することを繰り返し、右側に示す画質を改善した画像(積の画像、および和の画像)をそれぞれ生成する。   In FIG. 3B, a scanning waveform is acquired. Here, the scan waveform on the left side is the scan waveform from the image stored in the image file 7 of FIG. 1 in FIG. 3A (the horizontal direction is the scan line direction (equivalent to 512 pixels), and the vertical axis is the brightness at that time. Acquired scanning waveform). Then, paying attention to a scanning waveform having a left scanning waveform, a predetermined number (20 scanning lines in the example) before and after that is sequentially subjected to product operation or sum operation, and after normalization, as shown on the right side. In addition, storing the original scanning lines in a manner to replace the original is repeated to generate images (product images and sum images) with improved image quality shown on the right side.

図3の(c)は、エッジポイントを決める例を示す。図中の●のエッジポイントは、図3の(b)の右側の画質を改善した後の画像(積の場合、および和の場合)について、走査線毎にパターンのエッジに相当する当該走査線の最大ピークの点(あるいは走査線が所定閾値を横切る2点の中点)をエッジポイントとして決める。これら決めた●のエッジポイントについて、公知の最小二乗法によって直線近似した直線(パターンのエッジ)を図示の直線として生成する。そして、生成した直線の距離(寸法)をX1(〜Xn)として測長する。   FIG. 3C shows an example of determining an edge point. In FIG. 3B, the edge point of ● is the scanning line corresponding to the edge of the pattern for each scanning line in the image after improving the image quality on the right side of FIG. The maximum peak point (or the midpoint of two points where the scanning line crosses the predetermined threshold) is determined as an edge point. With respect to the determined edge points of ●, a straight line (pattern edge) approximated by a known least square method is generated as the straight line shown in the figure. Then, the distance (dimension) of the generated straight line is measured as X1 (to Xn).

図4は、本発明の説明図(再現性)を示す。図示の曲線は、既述した図3の(c)の最小二乗法によって直線近似した線分(パターンのエッジ)の距離(寸法)X1〜Xnについて、公知の偏差σ(含まれる確率が約68%)、偏差3σ(含まれる確率が約99.8%)を算出する様子を示す。σは、図示の下記の公知の式によって算出する。   FIG. 4 is an explanatory diagram (reproducibility) of the present invention. The curve shown in the figure shows a known deviation σ (with a probability of inclusion of about 68) for distances (dimensions) X1 to Xn of line segments (pattern edges) linearly approximated by the least square method of FIG. %) And deviation 3σ (the probability of being included is approximately 99.8%). σ is calculated by the following well-known formula shown in the figure.

・σ=√S
・S=1/(nΣ(Xm−Xa)2 )
(m=1〜n,Xa=X1〜Xnの平均)
・ Σ = √S
S = 1 / (nΣ (Xm−Xa) 2 )
(M = 1 to n, Xa = average of X1 to Xn)

本発明は、取得した複数毎の画像について注目するラインの所定数本の前後のラインの積を当該注目ラインに置き換えることを繰り返した画像を生成し、当該画像をもとに測長し、より再現性の高い測長を実現する画像位置測定方法および画像位置測定装置に関するものである。   The present invention generates an image in which the product of a predetermined number of lines before and after a plurality of lines of interest for each acquired plurality of images is replaced with the line of interest, measures the length based on the image, and more The present invention relates to an image position measuring method and an image position measuring apparatus that realize length measurement with high reproducibility.

本発明のシステム構成図である。It is a system configuration diagram of the present invention. 本発明の動作説明フローチャートである。It is an operation | movement explanatory flowchart of this invention. 本発明の説明図(手順)である。It is explanatory drawing (procedure) of this invention. 本発明の説明図(再現性)である。It is explanatory drawing (reproducibility) of this invention.

符号の説明Explanation of symbols

1:処理装置
2:画像取得手段
3:積算出手段
4:和算出手段
5:測長手段
6:比較・決定手段
7:画像ファイル
8:結果ファイル
9:表示装置
10:入力装置
11:画像
1: processing device 2: image acquisition means 3: product calculation means 4: sum calculation means 5: length measurement means 6: comparison / decision means 7: image file 8: result file 9: display device 10: input device 11: image

Claims (3)

画像上でパターンの測長を行う画像位置測定方法において、
同一の測長対象領域から複数の画像を取得するステップと、
前記取得した各画像中の注目するラインについて前後所定ラインの積を算出し、当該注目ラインに置き換えることを繰り返して画質を改善するステップと、
前記画質を改善した各画像中の測定対象のパターンの寸法を測長するステップと、
前記測長した各画像のパターンの寸法をもとに当該パターンの寸法を決定するステップと
を有する画像位置測定方法。
In an image position measuring method for measuring a pattern on an image,
Acquiring a plurality of images from the same length measurement target area;
Calculating the product of a predetermined line before and after the line of interest in each acquired image, and repeating the replacement with the line of interest to improve image quality; and
Measuring the dimension of the pattern to be measured in each image with improved image quality; and
And determining the dimension of the pattern based on the measured pattern dimension of each image.
前記各画像中の測定対象のパターンの寸法をもとに再現誤差を算出して当該再現誤差が所定閾値、あるいは前記積の代わりに和を用いて算出した値の再現誤差よりも小さいときに、前記決定したパターンの寸法を出力することを特徴とする請求項1記載の画像位置測定方法。   When a reproduction error is calculated based on the dimension of the pattern to be measured in each image and the reproduction error is smaller than a predetermined threshold, or a reproduction error of a value calculated using a sum instead of the product, 2. The image position measuring method according to claim 1, wherein the determined dimension of the pattern is output. 画像上でパターンの測長を行う画像位置測定装置において、
同一の測長対象領域から複数の画像を取得する手段と、
前記取得した各画像中の注目するラインについて前後所定ラインの積を算出し、当該注目ラインに置き換えることを繰り返して画質を改善する手段と、
前記画質を改善した各画像中の測定対象のパターンの寸法を測長する手段と、
前記測長した各画像のパターンの寸法をもとに当該パターンの寸法を決定する手段と
を備えたことを特徴とする画像位置測定装置。
In an image position measuring device that measures a pattern on an image,
Means for acquiring a plurality of images from the same length measurement target area;
Means for calculating the product of a predetermined line before and after the line of interest in each acquired image and repeatedly replacing the line of interest to improve image quality;
Means for measuring the dimension of the pattern to be measured in each image with improved image quality;
An image position measuring apparatus comprising: means for determining a dimension of the pattern based on the dimension of the pattern of each image that has been measured.
JP2005363292A 2005-12-16 2005-12-16 Image position measuring method and image position measuring instrument Pending JP2007163417A (en)

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