JP4357361B2 - A micro height measurement device using low coherence interferometry - Google Patents
A micro height measurement device using low coherence interferometry Download PDFInfo
- Publication number
- JP4357361B2 JP4357361B2 JP2004147532A JP2004147532A JP4357361B2 JP 4357361 B2 JP4357361 B2 JP 4357361B2 JP 2004147532 A JP2004147532 A JP 2004147532A JP 2004147532 A JP2004147532 A JP 2004147532A JP 4357361 B2 JP4357361 B2 JP 4357361B2
- Authority
- JP
- Japan
- Prior art keywords
- height
- point
- interference
- measurement
- difference
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Length Measuring Devices By Optical Means (AREA)
Description
本発明は、干渉光学系を利用して測定対象の微小高さを測定する測定装置に関し、特に低コヒーレンス干渉法を用いた微小高さ測定装置に関する。 The present invention relates to a measurement apparatus that measures a minute height of a measurement object using an interference optical system, and more particularly to a minute height measurement apparatus that uses a low coherence interferometry.
近年の電子機器の小型化に伴い、その内部に組み込まれる電子部品や材料の形状やサイズは多様化、微細化している。それに加えて、MEMS(Micro Electro Mechanical Systems)に代表されるデバイスは、ミクロンオーダの凹凸構造とナノメートルオーダの微細表面形状が混在している。こうした状況から、サブミクロンから数百ミクロンの高低差を持つ表面形状を、ナノメートルオーダの計測精度で精密に行う必要が生じている。 With the recent miniaturization of electronic devices, the shapes and sizes of electronic components and materials incorporated therein are diversified and miniaturized. In addition, devices represented by MEMS (Micro Electro Mechanical Systems) have a micron-order concavo-convex structure and a nanometer-order fine surface shape. Under these circumstances, it is necessary to precisely perform surface shapes having a height difference of submicron to several hundred microns with measurement accuracy on the order of nanometers.
このような微細表面形状の高さの測定には、一般に干渉光学系を利用した高精度干渉方式が用いられる。この高精度干渉方式の一つとして、例えば位相シフト干渉法がある。しかし、位相シフト干渉法で長レンジの高さを測定する場合には、測定結果に不連続な折り返しが生じる場合があり、この場合には、測定対象の表面が連続的に変化するという仮定を用いた位相接続(アンラッピング)処理を行う必要がある。しかしながら、表面形状に大きな段差がある場合には上記連続性の仮定が成り立たないため、測定が困難になる。これを回避する別の高精度干渉方式として、低コヒーレンス干渉法がある。 For the measurement of the height of such a fine surface shape, a high precision interference method using an interference optical system is generally used. One example of this high-accuracy interference method is phase shift interferometry. However, when measuring the height of a long range by phase shift interferometry, discontinuous folding may occur in the measurement result. In this case, it is assumed that the surface of the object to be measured changes continuously. It is necessary to perform the phase connection (unwrapping) process used. However, when there is a large step in the surface shape, the above continuity assumption does not hold, so measurement becomes difficult. Another high-precision interference method that avoids this is a low-coherence interference method.
図8は、低コヒーレンス干渉光学系を用いた従来の干渉計の構成例を表す説明図である。図8に示すように、従来の測定装置においては、光源部101から干渉縞距離が短い光(低コヒーレンス光)が、ステージ102上に載置された測定対象103と干渉レンズ104内の参照面に同時に照射される。そして、測定対象103の表面及び干渉レンズ104の参照面のそれぞれで反射した両反射光による干渉光の干渉縞が、CCD(Charge Coupled Device)カメラなどからなる撮像部105により観測される。この干渉縞は、ステージ102を測定対象103の高さ方向(z方向)に微小に動かしてサンプリングされるが、低コヒーレンス光によるため、測定対象103と参照面からの両反射光の光路差がゼロとなる場合の縞が最も振幅が大きくなり明るくなる。なお、図示の例ではステージ102の駆動により測定対象103をその高さ方向に動かしているが、干渉レンズ104を動かすようにしてもよい。 FIG. 8 is an explanatory diagram showing a configuration example of a conventional interferometer using a low coherence interference optical system. As shown in FIG. 8, in the conventional measuring apparatus, light having a short interference fringe distance (low coherence light) from the light source unit 101 is measured on the stage 102 and the reference surface in the interference lens 104. Are simultaneously irradiated. Then, the interference fringes of the interference light due to the both reflected lights reflected on the surface of the measurement object 103 and the reference surface of the interference lens 104 are observed by the imaging unit 105 including a CCD (Charge Coupled Device) camera or the like. The interference fringes are sampled by moving the stage 102 minutely in the height direction (z direction) of the measurement target 103, but because of the low coherence light, the optical path difference between the reflected light from the measurement target 103 and the reference surface is small. The stripes with zero amplitude have the largest amplitude and become brighter. In the illustrated example, the measurement object 103 is moved in the height direction by driving the stage 102, but the interference lens 104 may be moved.
図9は、従来の低コヒーレンス干渉法の測定原理を表す説明図である。すなわち、測定対象103の微小高さの測定は、測定対象103をある標本点間隔で垂直方向に動かすことにより得られるインターフェログラムから、上記光路差がゼロとなるステージ102の位置(一般には干渉強度が最大となるピーク位置)を干渉縞画像内の各点について検出することにより行われる(例えば特許文献1参照)。 FIG. 9 is an explanatory diagram showing the measurement principle of the conventional low coherence interferometry. That is, the measurement of the minute height of the measurement object 103 is performed by measuring the position of the stage 102 where the optical path difference is zero (generally interference) from an interferogram obtained by moving the measurement object 103 in the vertical direction at a certain sample point interval. This is performed by detecting each point in the interference fringe image (the peak position where the intensity is maximum) (see, for example, Patent Document 1).
すなわち、ステージ102の移動距離と、その移動で干渉強度が最大となる両インターフェログラムの間隔(画素数から算出される距離など)を算出することにより、その測定対象の両インターフェログラムの間隔においてステージ102の移動距離分の高さがあることが分かる。 That is, by calculating the moving distance of the stage 102 and the interval between the two interferograms where the interference intensity is maximized by the movement (such as the distance calculated from the number of pixels), the interval between the two interferograms to be measured is calculated. It can be seen that there is a height corresponding to the moving distance of the stage 102.
図10及び図11は、インターフェログラムのピーク位置の検出方法を示す説明図である。図11(A)は、本測定に際して作成される標本点列を表し、その横軸が測定対象103の位置を表し、縦軸が干渉光強度を表している。図11(B)は、本測定に際して算出される後述する特徴量の分布を表し、その横軸が測定対象103の位置を表し、縦軸が特徴量を表している。 10 and 11 are explanatory diagrams showing a method for detecting the peak position of the interferogram. FIG. 11A shows a sample point sequence created in the actual measurement, the horizontal axis thereof represents the position of the measurement target 103, and the vertical axis represents the interference light intensity. FIG. 11B shows a distribution of a feature amount, which will be described later, calculated at the time of the main measurement. The horizontal axis represents the position of the measurement target 103, and the vertical axis represents the feature amount.
すなわち、測定対象103の表面形状の計測においては、まず図10に示すように、測定対象103あるいは干渉レンズ104を測定対象103の高さ方向にある一定間隔(標本点間隔)で移動させつつ各干渉縞を撮像する。そして、図11(A)に示すように、このとき得られた干渉光強度をパラメータとする標本点列を作成する。 That is, in the measurement of the surface shape of the measurement target 103, first, as shown in FIG. 10, each measurement target 103 or the interference lens 104 is moved at regular intervals (sample point intervals) in the height direction of the measurement target 103. Image interference fringes. Then, as shown in FIG. 11A, a sample point sequence using the interference light intensity obtained at this time as a parameter is created.
続いて、この標本点列からインターフェログラムのピーク位置を求める。このピーク位置を精度良く求めるためには、光源の分光特性によって決まるナイキスト間隔以下の標本点間隔が必要となる。なお、可視光を使った場合には、この標本点間隔が数十nmとなるのが一般的である。 Subsequently, the peak position of the interferogram is obtained from this sample point sequence. In order to accurately obtain the peak position, a sample point interval equal to or smaller than the Nyquist interval determined by the spectral characteristics of the light source is required. When using visible light, the sample point interval is generally several tens of nanometers.
そして、これらの標本点列からピーク位置を求めるために、一般には、得られた標本点列のピーク位置を反映する特徴量が算出される。この特徴量には、例えば図11(B)に示すように、隣接標本点の干渉強度の差の絶対値が用いられる。同図には、特徴量から得られる近似曲線(最小二乗近似)が示されている。この近似曲線のピーク位置(図中矢印)を画像内各点について求めることにより測定対象103の表面形状が高精度に求まる。図示の例では、測定対象103の高さが0μmに位置しているインターフェログラムからピーク位置を求めた結果、ほぼ0μm位置に近似曲線のピーク位置が位置している。 In order to obtain the peak position from these sample point sequences, in general, a feature amount that reflects the peak position of the obtained sample point sequence is calculated. As this feature amount, for example, as shown in FIG. 11B, an absolute value of a difference in interference intensity between adjacent sample points is used. In the figure, an approximate curve (least square approximation) obtained from the feature amount is shown. By obtaining the peak position (arrow in the figure) of this approximate curve for each point in the image, the surface shape of the measuring object 103 can be obtained with high accuracy. In the illustrated example, as a result of obtaining the peak position from the interferogram in which the height of the measuring object 103 is located at 0 μm, the peak position of the approximate curve is located at approximately the 0 μm position.
このように、低コヒーレンス干渉法を用いると、白色光の短い可干渉距離(数μm)を利用して、サブミクロンから数百ミクロンの高低差を持つ長レンジの対象高さをナノメートルレベルで高精度に測定することができる。
しかしながら、低コヒーレンス干渉法により得られるインターフェログラムのピーク位置を精度良く求めるためには、光源の分光特性によって決まるナイキスト間隔以下の標本点間隔で複数枚の干渉縞画像を撮像する必要があり、ナイキスト間隔を超えて標本点間隔を設定した場合に問題が生じる。 However, in order to accurately determine the peak position of the interferogram obtained by low coherence interferometry, it is necessary to capture a plurality of interference fringe images at sample point intervals that are less than or equal to the Nyquist interval determined by the spectral characteristics of the light source. A problem arises when the sample point interval is set beyond the Nyquist interval.
図12は、上述した従来の測定方法で標本点間隔を広げた場合の問題点を表す説明図である。図12(A)は、この場合の測定に際して作成される標本点列を表し、その横軸が測定対象103の位置を表し、縦軸が干渉光強度を表している。図12(B)は、この場合の測定に際して算出される後述する特徴量の分布を表し、その横軸が測定対象103の位置を表し、縦軸が特徴量を表している。 FIG. 12 is an explanatory diagram showing a problem when the sample point interval is widened by the conventional measurement method described above. FIG. 12A shows a sample point sequence created in the measurement in this case, the horizontal axis represents the position of the measurement object 103, and the vertical axis represents the interference light intensity. FIG. 12B shows a distribution of a feature amount, which will be described later, calculated at the time of measurement in this case. The horizontal axis represents the position of the measurement target 103 and the vertical axis represents the feature amount.
すなわち、図12(A)に示すように、ナイキスト間隔を超えて標本点間隔を設定した場合に、図12(B)に矢印で示すように、本来0μmであるはずのピーク位置がずれて計測精度が大幅に低下していることが分かる。 That is, as shown in FIG. 12 (A), when the sample point interval is set beyond the Nyquist interval, the peak position which should originally be 0 μm is shifted as shown by the arrow in FIG. 12 (B). It can be seen that the accuracy is greatly reduced.
以上に説明したように、従来の測定方法で長レンジの高さを持つ測定対象の高さを精度よく測定するためには、光源の分光特性から決まる標本点間隔に従って干渉縞画像を撮像する必要がある。このため、干渉縞画像の撮像枚数が増えて撮像時間が長くなり、サンプリングデータを格納するために必要なメモリの容量が増大したり、測定に要する計算時間が長くなるため、計算コストが増大するという問題があった。 As described above, in order to accurately measure the height of a measurement object having a long range height with the conventional measurement method, it is necessary to capture an interference fringe image according to the sample point interval determined from the spectral characteristics of the light source. There is. For this reason, the number of interference fringe images to be captured increases and the imaging time becomes longer, the memory capacity necessary for storing sampling data increases, and the calculation time required for measurement increases, resulting in an increase in calculation cost. There was a problem.
本発明はこのような点に鑑みてなされたものであり、低コヒーレンス干渉法を利用して長レンジの高さを持つ測定対象の高さを精度よく測定できる測定方法及び測定装置を提供し、特に、測定時に要されるメモリの容量や計算時間を低減して計算コストを抑えることができるようにすることを目的とする。 The present invention has been made in view of such points, and provides a measurement method and a measurement apparatus that can accurately measure the height of a measurement object having a long range height using low coherence interferometry, In particular, it is an object of the present invention to reduce the memory cost and calculation time required at the time of measurement so as to reduce the calculation cost.
本発明では上記問題を解決するために、図1に示したように、予め設定された中心波長を有する低コヒーレンス光を照射可能な光源部1と、光源部1からの照射光を測定対象7の物体表面及び参照物6の参照面のそれぞれで反射させ、両反射光を干渉させる干渉光学系2と、測定対象7及び参照物6の少なくとも一方を移動可能に支持するステージ10と、ステージ10を駆動することにより物体表面と参照面との距離を調整可能な位置調整機構3と、両反射光の干渉縞画像を撮像して取得する撮像部4と、撮像部4で取得された干渉縞画像を用いて物体表面の高さを測定する演算制御部5とを備えた微小高さ測定装置が提供される。この演算制御部5は、干渉光強度測定手段、特徴量算出手段、サンプリング手段、及び高さ算出手段を備える。 In the present invention, in order to solve the above problem, as shown in FIG. 1, a light source unit 1 capable of irradiating low-coherence light having a preset center wavelength, and irradiation light from the light source unit 1 are measured 7. The interference optical system 2 that reflects the object surface and the reference surface of the reference object 6 and interferes both reflected light, the stage 10 that movably supports at least one of the measurement object 7 and the reference object 6, and the stage 10 , The position adjustment mechanism 3 that can adjust the distance between the object surface and the reference surface, the imaging unit 4 that captures and acquires the interference fringe images of both reflected lights, and the interference fringes acquired by the imaging unit 4 There is provided a minute height measuring apparatus including an arithmetic control unit 5 that measures the height of an object surface using an image. The arithmetic control unit 5 includes interference light intensity measurement means, feature amount calculation means, sampling means, and height calculation means.
干渉光強度測定手段は、撮像部により撮像された干渉縞画像に、物体表面における注目点とその近傍点とを設定し、注目点と近傍点における干渉光強度をそれぞれ測定する。
特徴量算出手段は、注目点と近傍点との高低差により生じる両干渉光強度の差分の絶対値を、ステージ10を上記高低差分移動したときの注目点における両干渉光強度の差分の絶対値とみなして、これを特徴量として算出する。
The interference light intensity measuring means sets a point of interest on the object surface and its neighboring points in the interference fringe image picked up by the imaging unit, and measures the interference light intensity at the point of interest and the neighboring points, respectively.
The feature amount calculating means calculates the absolute value of the difference between the two interference light intensities caused by the difference in height between the attention point and the neighboring point, and the absolute value of the difference between the two interference light intensities at the attention point when the stage 10 is moved by the height difference. This is calculated as a feature amount.
サンプリング手段は、位置調整機構3によりステージ10を所定の標本点間隔ずつ移動させて順次算出された特徴量の分布をサンプリングする。
高さ算出手段は、特徴量の分布から特徴量のピーク位置を検出し、特徴量がピーク位置となるステージ10の位置を検出することにより、測定対象7の高さを算出する。
The sampling means samples the distribution of the feature amount sequentially calculated by moving the stage 10 by a predetermined sampling point interval by the position adjusting mechanism 3.
The height calculation means calculates the height of the measurement object 7 by detecting the peak position of the feature quantity from the distribution of the feature quantity and detecting the position of the stage 10 at which the feature quantity is the peak position.
このような微小高さ測定方法によれば、干渉縞画像に注目点と近傍点とが設定され、その注目点と近傍点における干渉光強度がそれぞれ測定されるが、注目点と近傍点との高低差により生じる両干渉光強度の差分の絶対値が、ステージ10を高低差分移動したときの注目点における両干渉光強度の差分の絶対値とみなされ、特徴量が算出される。 According to such a minute height measuring method, a point of interest and a neighboring point are set in the interference fringe image, and the interference light intensity at the point of interest and the neighboring point is measured. The absolute value of the difference between the two interference light intensities caused by the height difference is regarded as the absolute value of the difference between the two interference light intensities at the point of interest when the stage 10 is moved by the difference in height, and the feature amount is calculated.
本発明の微小高さ測定装置では、注目点と近傍点との高低差により生じる両干渉光強度の差分の絶対値が、ステージを高低差分移動したときの注目点における両干渉光強度の差分の絶対値とみなされるため、この注目点について、近傍点に相当する位置にステージを動かしてその干渉光強度を測定する必要がなくなる。 In the minute height measurement apparatus of the present invention, the absolute value of the difference between the two interference light intensities caused by the difference in height between the attention point and the neighboring point is the difference between the two interference light intensity differences at the attention point when the stage is moved in the height difference. Since it is regarded as an absolute value, there is no need to measure the interference light intensity by moving the stage to a position corresponding to a neighboring point for this attention point.
このため、ステージの移動回数を減らすことができ、計算時間を短縮することができる。また、注目点とその近傍点との干渉光強度を測定するために、干渉光強度が急峻に変化する位置、つまり干渉光強度のピーク位置を検出し易くなる。この結果、ステージを移動してサンプリングする際の標本点間隔を広げて計測を行った場合にも、精度良く測定対象の高さ、ひいては表面形状を測定することができる。さらに、このように標本点間隔を広げることにより、サンプリング数が少なくなり、計測時の必要メモリや計算時間等の計算コストを抑えて計測の高速化を図ることができる。 For this reason, the number of stage movements can be reduced, and the calculation time can be shortened. Further, in order to measure the interference light intensity between the attention point and its neighboring points, it is easy to detect the position where the interference light intensity changes sharply, that is, the peak position of the interference light intensity. As a result, even when the measurement is performed by moving the stage and widening the sampling point interval when sampling, the height of the measurement object, and thus the surface shape can be measured with high accuracy. Furthermore, by widening the sampling point interval in this way, the number of samplings can be reduced, and the measurement speed can be increased by reducing the calculation cost such as the required memory and calculation time during measurement.
以下、本発明の実施の形態を図面を参照して説明する。図1は、本発明の実施の形態の微小高さ測定装置の構成例を示す図である。
この微小高さ測定装置は、光源部1,干渉光学系2,位置調整機構3,撮像部4,及び演算制御部5を備えており、位相シフト干渉計として構成されている。
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration example of a minute height measuring apparatus according to an embodiment of the present invention.
This minute height measuring apparatus includes a light source unit 1, an interference optical system 2, a position adjustment mechanism 3, an imaging unit 4, and a calculation control unit 5, and is configured as a phase shift interferometer.
光源部1は、中心波長が干渉縞距離が短い光(低コヒーレンス光)を照射可能なものである。この例では、白色光源が用いられる。
干渉光学系2は、光路分岐用のハーフミラーと、参照面を有する干渉レンズ6(参照物)とを備えている。この干渉光学系2は、光源部1からの照射光を一旦分岐させて、測定対象7の物体表面と干渉レンズ6の参照面とのそれぞれで反射させ、戻ってきた両反射光を干渉させる。
The light source unit 1 is capable of irradiating light having a center wavelength and a short interference fringe distance (low coherence light). In this example, a white light source is used.
The interference optical system 2 includes a half mirror for branching an optical path and an interference lens 6 (reference object) having a reference surface. The interference optical system 2 once divides the irradiation light from the light source unit 1 and reflects it on each of the object surface of the measuring object 7 and the reference surface of the interference lens 6, and causes both reflected light beams that have returned to interfere with each other.
位置調整機構3は、参照面を光軸方向に沿って移動させるためのピエゾドライバ8と、測定対象7の物体表面を光軸方向及び光軸に垂直な方向に移動させたり、高さ方向に傾けたりするためのステージドライバ9とを備えている。ピエゾドライバ8は、演算制御部5からの指令により、干渉レンズ6を装着したピエゾステージ10を駆動する。このピエゾステージ10には、ピエゾ素子が組み込まれている。ステージドライバ9は、演算制御部5からの指令により、測定対象7を載置した移動ステージ11を駆動する。この移動ステージ11の駆動により、測定対象7の関心のある位置が撮像部4の視野内に入れられる。 The position adjusting mechanism 3 moves the reference surface along the optical axis direction, and moves the object surface of the measuring object 7 in the optical axis direction and the direction perpendicular to the optical axis, or in the height direction. A stage driver 9 for tilting is provided. The piezo driver 8 drives the piezo stage 10 on which the interference lens 6 is mounted according to a command from the arithmetic control unit 5. This piezo stage 10 incorporates a piezo element. The stage driver 9 drives the moving stage 11 on which the measurement object 7 is placed according to a command from the arithmetic control unit 5. By driving the moving stage 11, the position of interest of the measuring object 7 is placed in the field of view of the imaging unit 4.
撮像部4は、CCDカメラ等の2次元撮像装置からなり、上記両反射光の干渉縞画像を撮像する。
演算制御部5は、CPU(Central Processing Unit)を中心に構成されたコンピュータからなり、後述する処理機能に伴う演算処理を実行したり、ピエゾドライバ8やステージドライバ9、その他のアクチュエータに制御指令信号を出力したりする。この演算制御部5は、撮像部4で撮像された画像データを蓄積するメモリ等の記憶装置や、演算結果を適宜画面に出力するための表示装置などを備えている。
The imaging unit 4 includes a two-dimensional imaging device such as a CCD camera and captures the interference fringe image of the both reflected lights.
The arithmetic control unit 5 is composed of a computer centered on a CPU (Central Processing Unit), executes arithmetic processing associated with processing functions to be described later, and sends control command signals to the piezo driver 8, the stage driver 9, and other actuators. Is output. The arithmetic control unit 5 includes a storage device such as a memory for accumulating image data picked up by the image pickup unit 4, a display device for appropriately outputting the calculation result to the screen, and the like.
以上のように構成された微小高さ測定装置において、光源部1から射出された低コヒーレンス光は、測定対象7の物体表面と干渉レンズ6内の参照面に同時に照射される。そして、これら物体表面及び参照面のそれぞれで反射した両反射光が合流して、撮像部4の撮像面に干渉縞画像を作る。演算制御部5は、この撮像部4で撮像された干渉縞画像をデジタル画像として取り込んで解析する。この干渉縞は、移動ステージ11を測定対象7の高さ方向に微小に動かしてサンプリングされるが、物体表面と参照面からの両反射光の光路差がゼロとなる場合の縞が最も振幅が大きくなり明るくなる。 In the micro-height measuring apparatus configured as described above, the low coherence light emitted from the light source unit 1 is simultaneously irradiated onto the object surface of the measurement target 7 and the reference surface in the interference lens 6. Then, both reflected lights reflected by the object surface and the reference surface are merged to form an interference fringe image on the imaging surface of the imaging unit 4. The arithmetic control unit 5 captures and analyzes the interference fringe image captured by the imaging unit 4 as a digital image. The interference fringes are sampled by moving the moving stage 11 in the height direction of the measuring object 7, and the fringes when the optical path difference between the reflected light from the object surface and the reference surface is zero have the largest amplitude. Bigger and brighter.
なお、以上においては、いわゆる位相シフト干渉計の一例を示したが、ミロー型干渉計その他の位相シフト干渉計を用いてもよい。
次に、本実施の形態の微小高さ測定方法について説明する。
In the above, an example of a so-called phase shift interferometer has been shown, but a mirrow interferometer or other phase shift interferometer may be used.
Next, the minute height measuring method of the present embodiment will be described.
まず、図示しないハンドラ等から測定対象7を移動ステージ11上に設置する。演算制御部5は、図示しないセンサの出力により、測定対象7が移動ステージ11に設置されたと判断すると、ステージドライバ9を介して移動ステージを水平方向、高さ方向あるいは傾き方向に駆動して、測定対象7を所定位置まで動かして測定準備を行う。 First, the measuring object 7 is set on the moving stage 11 from a handler or the like (not shown). When the calculation control unit 5 determines that the measurement object 7 is installed on the moving stage 11 based on the output of a sensor (not shown), the calculation control unit 5 drives the moving stage in the horizontal direction, the height direction, or the tilt direction via the stage driver 9. The measurement object 7 is moved to a predetermined position to prepare for measurement.
そして、光源部1から低コヒーレンス光が射出され、干渉レンズ6を通って測定対象7に照射される。このとき、干渉レンズ6の参照面と測定対象7の物体表面で反射された反射光が、これら参照面と物体表面との相対距離に応じて干渉し、その干渉縞が撮像部4により撮像される。干渉レンズ6は、ピエゾドライバ8を介してピエゾステージ10により微小量上下することができるようになっており、測定準備の段階で測定対象7の注目領域で光路差がゼロとなるような範囲を含むことができるようにあらかじめ高さ方向の位置決めを行っておく。 Then, low-coherence light is emitted from the light source unit 1, and is irradiated onto the measurement object 7 through the interference lens 6. At this time, the reflected light reflected by the reference surface of the interference lens 6 and the object surface of the measurement object 7 interferes according to the relative distance between the reference surface and the object surface, and the interference fringes are imaged by the imaging unit 4. The The interference lens 6 can be moved up and down by a small amount by a piezo stage 10 via a piezo driver 8 and has a range in which the optical path difference is zero in the attention area of the measurement object 7 at the stage of measurement preparation. Positioning in the height direction is performed in advance so that it can be included.
以上の測定準備が整うと、その旨を表す信号が演算制御部5に入力される。演算制御部5は、これを受けてピエゾステージ10を所定の初期位置まで動かし、撮像部4で撮像された干渉縞画像をデジタル画像として取り込み、内部のメモリに蓄積する。 When the above measurement preparation is completed, a signal indicating that is input to the arithmetic control unit 5. In response to this, the arithmetic control unit 5 moves the piezo stage 10 to a predetermined initial position, captures the interference fringe image picked up by the image pickup unit 4 as a digital image, and stores it in an internal memory.
続いて、演算制御部5は、ピエゾステージ10を予め設定した標本点間隔分移動して再び干渉縞画像を取り込む。演算制御部5は、この動作を繰り返し、所定の距離を移動して複数枚の干渉縞画像が得られると、後述する測定原理にしたがって測定対象7の表面高さの算出を行う。 Subsequently, the arithmetic control unit 5 moves the piezo stage 10 by a preset sample point interval and captures the interference fringe image again. The arithmetic control unit 5 repeats this operation, and when a plurality of interference fringe images are obtained by moving a predetermined distance, the surface height of the measurement object 7 is calculated according to the measurement principle described later.
そして、測定対象7のある領域の表面高さの算出が終了すると、演算制御部5は、ピエゾステージ10と移動ステージ11を適宜動かし、測定点を測定対象7上の次の測定点に移動させる。演算制御部5は、この測定処理の過程でその演算結果を適宜表示装置に出力する。 When the calculation of the surface height of a certain area of the measurement object 7 is completed, the arithmetic control unit 5 moves the piezo stage 10 and the moving stage 11 as appropriate, and moves the measurement point to the next measurement point on the measurement object 7. . The calculation control unit 5 appropriately outputs the calculation result to the display device during the measurement process.
次に、演算制御部5により実行される測定処理の測定原理について説明する。図2は、微小高さの測定原理を表す説明図である。
本実施の形態では、測定対象の表面における各点のインターフェログラムを求めるときに、図2に示すように、同一干渉縞画像内に注目点とその近傍点とを設定する。この近傍点は、例えば注目点から数画素分離れた位置に設定することができる。そして、測定対象の表面形状がこの注目点近傍において一定の変化を有する同質のものと仮定して、この注目点の干渉光強度と近傍点の干渉光強度との差の絶対値を特徴量とする。
Next, the measurement principle of the measurement process executed by the arithmetic control unit 5 will be described. FIG. 2 is an explanatory diagram showing the measurement principle of the minute height.
In the present embodiment, when an interferogram of each point on the surface of the measurement target is obtained, the point of interest and its neighboring points are set in the same interference fringe image as shown in FIG. This neighboring point can be set, for example, at a position several pixels away from the point of interest. Assuming that the surface shape of the measurement target is the same quality having a constant change in the vicinity of this point of interest, the absolute value of the difference between the interference light intensity at this point of interest and the interference light intensity at the nearby point is defined as the feature amount. To do.
すなわち、図9で示した従来例では、測定対象の表面にある注目点を設定して測定対象を光路に垂直に移動し、その注目点の干渉光強度の差の絶対値を特徴量として高さを求めたため、干渉光強度のサンプリングごとに測定対象を移動する必要があった。これに対し、本発明では、図2に示したように、あるサンプリング位置で注目点と近傍点との2点についてサンプリングし、そのとき近傍点で測定された干渉光強度を、注目点のインターフェログラムにおいて近傍点の位相と対応する未測定部分の干渉光強度とみなして計算を進める。これは、上記のように測定対象の表面状態が同質であると仮定すると、測定対象の表面の近接した2点で得られる2つのインターフェログラムの形状が理想的には同じになる。このため、測定対象の表面のわずかな高低差による近傍点間の干渉光強度の差が、高低差を標本点間隔とみなした場合の垂直方向の干渉光強度の差と同じとなることを利用したものである。 That is, in the conventional example shown in FIG. 9, a point of interest on the surface of the measurement target is set, the measurement target is moved perpendicularly to the optical path, and the absolute value of the difference in the interference light intensity at that point of interest is high as the feature quantity. Therefore, it was necessary to move the measurement object for each sampling of the interference light intensity. On the other hand, in the present invention, as shown in FIG. 2, sampling is performed for two points, that is, a point of interest and a neighboring point at a certain sampling position, and the interference light intensity measured at the neighboring point at that time is measured as an In the pherogram, the calculation proceeds with the interference light intensity of the unmeasured part corresponding to the phase of the neighboring point. Assuming that the surface condition of the measurement target is homogeneous as described above, the shapes of the two interferograms obtained at two adjacent points on the surface of the measurement target are ideally the same. For this reason, it is used that the difference in the interference light intensity between neighboring points due to the slight difference in height of the surface of the measurement object is the same as the difference in the interference light intensity in the vertical direction when the height difference is regarded as the sample point interval. It is a thing.
そして、上述した操作を測定対象の高さ方向にある間隔で繰り返せば、注目点と近傍点間の干渉強度差をパラメータとした標本点列が得られる。この場合、標本点列の標本点間隔はナイキスト間隔以下にした状態で1回の撮像で標本点が2点得られるので撮像時間をほぼ半分にできる。その結果、測定対象が長レンジの高さを有していても、その高さを精度よく測定でき、また、測定時に要されるメモリの容量や計算時間を低減して計算コストを抑えることができる。 If the above-described operation is repeated at an interval in the height direction of the measurement target, a sample point sequence using the difference in interference intensity between the attention point and the neighboring points as a parameter can be obtained. In this case, since the sample point interval of the sample point sequence is equal to or less than the Nyquist interval, two sample points can be obtained by one image pickup, so that the image pickup time can be almost halved. As a result, even if the measurement target has a long range height, the height can be measured accurately, and the memory capacity and calculation time required for measurement can be reduced to reduce the calculation cost. it can.
なお、以上においては、注目点の干渉光強度と近傍点の干渉光強度との差の絶対値を特徴量としたが、同一干渉縞画像内の注目点と近傍点の干渉光強度を使って算出できる可視度(ビジビリティ、コントラスト)を特徴量としてもよい。この場合、注目点と少なくとも2つの近傍点の干渉光強度により、1つの可視度を算出できる。 In the above, the absolute value of the difference between the interference light intensity at the attention point and the interference light intensity at the neighboring point is used as the feature amount, but the interference light intensity between the attention point and the neighboring point in the same interference fringe image is used. Visibility (visibility and contrast) that can be calculated may be used as the feature amount. In this case, one visibility can be calculated from the interference light intensity of the attention point and at least two neighboring points.
図3は、各サンプリング位置で測定点を3つにした場合の演算例を表す説明図である。
この例では、図2で示した演算例に対して測定点をもう一箇所増やし、測定対象の注目点の両側に等間隔(同じ画素数)である2つの近傍点を設定し、その注目点の干渉光強度と両近傍点それぞれの干渉光強度との差を算出する。そして、その2つの干渉光強度の差の絶対値の大きい方を特徴量とする。
FIG. 3 is an explanatory diagram showing an example of calculation when there are three measurement points at each sampling position.
In this example, the number of measurement points is increased by one more from the calculation example shown in FIG. 2, and two neighboring points with equal intervals (the same number of pixels) are set on both sides of the target point of measurement. The difference between the interference light intensity of each and the interference light intensity of each of the neighboring points is calculated. Then, the larger absolute value of the difference between the two interference light intensities is set as the feature amount.
すなわち、図3に示すように、図示中央のインターフェログラムによる注目点の干渉光強度と図示左側のインターフェログラムによる第1近傍点の干渉光強度との差である光強度差Aと、その注目点の干渉光強度と図示右側のインターフェログラムによる第2近傍点の干渉光強度との差である光強度差Bとをそれぞれ算出し、大きい方の光強度差Aを特徴量とする。ただし、注目点と第1近傍点との高低差aと、注目点と第2近傍点との高低差bとがほぼ同じとなることを前提とする。ここで、両光強度差のうち大きい方のみを特徴量としたのは、特徴量のピーク位置を求めるのが目的であるため、大きい方のみの情報が分かればよいためである。 That is, as shown in FIG. 3, a light intensity difference A that is a difference between the interference light intensity at the point of interest by the interferogram in the center of the figure and the interference light intensity at the first neighboring point by the interferogram on the left side of the figure, A light intensity difference B, which is the difference between the interference light intensity at the point of interest and the interference light intensity at the second neighboring point according to the interferogram on the right side of the figure, is calculated, and the larger light intensity difference A is used as the feature amount. However, it is assumed that the height difference a between the attention point and the first neighboring point and the height difference b between the attention point and the second neighboring point are substantially the same. Here, the reason that only the larger one of the two light intensity differences is used as the feature amount is that the purpose is to obtain the peak position of the feature amount, so that only the larger information needs to be known.
図4は、測定対象の撮像高さ位置に対する特徴量を演算したシミュレーション結果を表す説明図である。(A)は、図3のように各撮像高さ位置で測定点を3箇所設定して演算した結果を表すグラフであり、(B)は、その比較例として図9のように各撮像高さ位置で測定点を1箇所設定する従来手法で演算した結果を表すグラフである。両グラフとも、その横軸が測定対象の位置を表し、縦軸が特徴量を表しており、光路差ゼロの位置を高さ約4μmの位置に設定した場合のシミュレーション結果を示している。なお、同図には、角点で示した実際の標本点間隔毎の特徴量に加え、参照として標本点間隔を極めて小さくした場合の特徴量の値(波形)を併記している。 FIG. 4 is an explanatory diagram illustrating a simulation result obtained by calculating a feature amount with respect to an imaging height position of a measurement target. (A) is a graph showing the result of calculation by setting three measurement points at each imaging height position as shown in FIG. 3, and (B) shows each imaging height as a comparative example as shown in FIG. It is a graph showing the result calculated by the conventional method which sets one measurement point in the position. In both graphs, the horizontal axis represents the position of the measurement target, the vertical axis represents the feature amount, and the simulation result is shown when the position of zero optical path difference is set to a position of about 4 μm in height. In the figure, in addition to the feature quantity for each actual sampling point interval indicated by the corner points, the value (waveform) of the feature quantity when the sampling point interval is extremely small is also shown as a reference.
このシミュレーション結果によれば、図4(B)の比較例(従来法)では、撮像間隔すなわち標本点間隔によっては、同図に示したように偽のピーク位置が表れることがある。
これに対し、図4(B)の本手法では、グラフの形状がほぼ単峰であるために、標本点間隔にあまり影響されずにピーク位置を検出できる。
According to this simulation result, in the comparative example (conventional method) of FIG. 4B, a false peak position may appear as shown in FIG. 4 depending on the imaging interval, that is, the sampling point interval.
On the other hand, in the present method shown in FIG. 4B, since the shape of the graph is almost unimodal, the peak position can be detected without much influence from the sample point interval.
図5は、上述した測定方法で標本点間隔を広げた場合の特徴量のピーク位置の検出例を表す説明図である。(A)は、この場合の測定に際して作成される標本点列を表し、その横軸が測定対象7の位置を表し、縦軸が干渉光強度を表している。(B)は、この場合の測定に際して算出される後述する特徴量の分布を表し、その横軸が測定対象7の位置を表し、縦軸が特徴量を表している。 FIG. 5 is an explanatory diagram illustrating a detection example of the peak position of the feature amount when the sample point interval is widened by the measurement method described above. (A) represents the sample point sequence created in the measurement in this case, the horizontal axis represents the position of the measuring object 7, and the vertical axis represents the interference light intensity. (B) represents a distribution of a feature amount, which will be described later, calculated at the time of measurement in this case, the horizontal axis represents the position of the measurement object 7, and the vertical axis represents the feature amount.
図5(B)によれば、ナイキスト間隔を超えて標本点間隔を設定した場合でも、光路差ゼロのピーク位置(図中0μm)を精度良く示しており、標本点間隔を大きくしても、注目点と近傍点間のわずかな高低差を利用して精度良く高さを得ることができることが分かる。これは、以下の理由によるものと考えられる。 According to FIG. 5 (B), even when the sample point interval is set beyond the Nyquist interval, the peak position of zero optical path difference (0 μm in the figure) is shown accurately, and even if the sample point interval is increased, It can be seen that the height can be obtained with high accuracy by using a slight difference in height between the point of interest and the neighboring points. This is considered to be due to the following reasons.
すなわち、図4(B)に示すように、隣接標本点間の差の絶対値を特徴量とした場合には、隣接する標本点間の干渉光強度の差が大きく変動する位置を何度も経るため、特徴量が大きく変動し易くなる。このため、標本点間隔が大きいと、特徴量の大きい箇所をサンプリングし難くなり、特徴量のピーク位置を誤って検出する場合が生じる。 That is, as shown in FIG. 4B, when the absolute value of the difference between adjacent sample points is used as a feature amount, the position where the difference in interference light intensity between adjacent sample points greatly fluctuates many times. Therefore, the feature amount is likely to fluctuate greatly. For this reason, if the sampling point interval is large, it is difficult to sample a portion having a large feature amount, and the peak position of the feature amount may be detected erroneously.
これに対し、図4(A)に示すように、2つの干渉光強度の差の絶対値の小さい方を特徴量として無視する場合には、隣接する標本点間の干渉光強度の差が大きく変動する位置を経る確率が少なくなるため、特徴量の変動が小さくなる。このため、グラフが単峰に近くなって、標本点間隔が大きくても特徴量の大きい箇所をサンプリングし易くなり、特徴量のピーク位置を誤って検出することを防止又は抑制することができる。以上の理由から、本手法により測定精度が向上する。 On the other hand, as shown in FIG. 4A, when the smaller absolute value of the difference between the two interference light intensities is ignored as the feature amount, the difference in the interference light intensity between adjacent sample points is large. Since the probability of passing through the fluctuating position is reduced, the fluctuation of the feature amount is reduced. For this reason, the graph is close to a single peak, and even if the sampling point interval is large, it becomes easy to sample a portion having a large feature amount, and it is possible to prevent or suppress erroneous detection of the peak position of the feature amount. For the above reasons, the measurement accuracy is improved by this method.
なお、以上に示した低コヒーレンス干渉光学系においては、図3で示した高低差が光源波長に対してある範囲にあれば計測精度的に有利であることが、出願人らのシミュレーションの結果により判明した。 In the low coherence interference optical system shown above, it is advantageous from the simulation results of the applicants that the measurement accuracy is advantageous if the height difference shown in FIG. 3 is within a certain range with respect to the light source wavelength. found.
図6は、図3で示した高低差の設定と測定精度との関係を表す説明図である。ここでは、図4(A)のグラフの頂点付近であるA部について、下記式(1)で求められるV値を定義し、このV値が高低差によってどのように変化するかをシミュレーションした。図6は、そのシミュレーション結果を表すグラフであり、その横軸が高低差を表し、縦軸がV値を表している。なお、このときの光源の中心波長は約580nmとし、図3のように隣接する近傍点の高低差a,bをほぼ同じにした。 FIG. 6 is an explanatory diagram showing the relationship between the setting of the height difference shown in FIG. 3 and the measurement accuracy. Here, the V value calculated | required by following formula (1) is defined about A part which is the vertex vicinity of the graph of FIG. 4 (A), and it was simulated how this V value changes with a height difference. FIG. 6 is a graph showing the simulation results, where the horizontal axis represents the height difference and the vertical axis represents the V value. At this time, the center wavelength of the light source was about 580 nm, and the height differences a and b of adjacent neighboring points were made substantially the same as shown in FIG.
V=(Max−Min)/(Max+Min) ・・・(1)
ここで、Maxは、図4(A)のグラフに示される特徴量を表す波形の山の部分の値であり、MinはこのMaxに隣接する谷の部分の値である。上記式(1)から、0<V<1であり、図4(A)のグラフが単峰に近づくほどV値が小さくなる。つまり、V値が小さくなるほど特徴量の変動が小さくなり、特徴量のピーク値の検出精度が向上する。
V = (Max−Min) / (Max + Min) (1)
Here, Max is the value of the peak portion of the waveform representing the feature amount shown in the graph of FIG. 4A, and Min is the value of the valley portion adjacent to this Max. From the above equation (1), 0 <V <1, and the V value decreases as the graph of FIG. That is, the smaller the V value, the smaller the variation in the feature value, and the more accurate the detection of the peak value of the feature value.
図6によれば、高低差が約75nmのときにV値が極小値をとることが分かる。すなわち、高低差が光源の中心波長の約1/8となるときにV値が最小となり、中心波長の1/9〜1/7(特に中心波長の1/8の前後10%)となるときに特に良好な測定精度が得られることが分かった。 According to FIG. 6, it can be seen that the V value takes a minimum value when the height difference is about 75 nm. That is, when the height difference is about 1/8 of the center wavelength of the light source, the V value is minimum, and when it is 1/9 to 1/7 of the center wavelength (especially 10% around 1/8 of the center wavelength). It was found that particularly good measurement accuracy can be obtained.
このように高低差を光源波長の1/8程度に保つのが計測精度的に有利であることが分かったため、注目点と近傍点との距離を上記高低差になるように選んでもよいし、注目点と近傍点間の高低差が適当になるように測定対象7を傾けてもよい。 Since it has been found that it is advantageous in terms of measurement accuracy to maintain the height difference to about 1/8 of the light source wavelength in this way, the distance between the point of interest and the neighboring point may be selected to be the above height difference, The measuring object 7 may be tilted so that the height difference between the attention point and the neighboring points is appropriate.
図7は、測定対象7の注目点と近傍点の間に全く高低差がない場合の演算例を示す説明図である。
すなわち、注目点と近傍点とを結ぶ方向に高低差がない場合には、測定対象7を傾けるなどして意図的に高低差を作らずに、測定対象7をその表面と垂直方向に必要な高低差分動かしてデータを取り、標本点間隔分動かすという動作を繰り返してもよい。
FIG. 7 is an explanatory diagram illustrating a calculation example in the case where there is no height difference between the attention point and the neighboring points of the measurement object 7.
That is, when there is no height difference in the direction connecting the attention point and the neighboring points, the measurement object 7 is necessary in the direction perpendicular to the surface without intentionally creating a height difference by tilting the measurement object 7 or the like. It is also possible to repeat the operation of taking the data by moving the difference in height and moving it by the sampling point interval.
あるいは、図示しないが、図3の方法で対象の傾きを変えて2回以上計測を行うことにより、注目点と近傍点に高低差がない箇所を補いながらデータを得てもよい。
以上のように、本手法により、標本点間隔を大きくしても、高速化を図りつつ低コヒーレンス干渉法の原理を利用して精度良く測定対象の高さを得ることができる。
Alternatively, although not shown, data may be obtained while compensating for a portion where there is no difference in height between the attention point and the neighboring points by performing the measurement twice or more by changing the inclination of the object by the method of FIG.
As described above, according to the present method, the height of the measurement object can be obtained with high accuracy using the principle of the low coherence interferometry while increasing the speed even if the sampling point interval is increased.
以上説明したように、本発明の微小高さ測定装置によれば、長レンジの高さを持つ測定対象の測定に際して、測定時の必要メモリや計算時間等の計算コストを抑えて計測の高速化を図るために、標本点間隔を広げて計測を行った場合にも、その測定対象の高さ、ひいては表面形状を精度よく測定することができる。 As described above, according to the micro height measurement apparatus of the present invention, when measuring a measurement object having a long range height, the measurement cost is reduced by suppressing the calculation cost such as memory required for measurement and calculation time. Therefore, even when the measurement is performed with a wide sampling point interval, the height of the measurement object, and thus the surface shape, can be measured with high accuracy.
なお、上述した演算制御部5が実行する各処理機能はコンピュータによって実現されるが、その場合、各機能の処理内容を記述したプログラムが提供される。そのプログラムをコンピュータで実行することにより、上記処理機能がコンピュータ上で実現される。処理内容を記述したプログラムは、コンピュータで読み取り可能な記録媒体に記録しておくことができる。コンピュータで読み取り可能な記録媒体としては、磁気記録装置、光ディスク、光磁気記録媒体、半導体メモリなどがある。磁気記録装置には、ハードディスク装置(HDD)、フレキシブルディスク(FD)、磁気テープなどがある。光ディスクには、DVD(Digital Versatile Disc)、DVD−RAM(Random Access Memory)、CD−ROM(Compact Disc Read Only Memory)、CD−R(Recordable)/RW(ReWritable)などがある。光磁気記録媒体には、MO(Magneto-Optical disk)などがある。 In addition, although each processing function which the arithmetic control part 5 mentioned above performs is implement | achieved by the computer, the program which described the processing content of each function is provided in that case. By executing the program on a computer, the above processing functions are realized on the computer. The program describing the processing contents can be recorded on a computer-readable recording medium. Examples of the computer-readable recording medium include a magnetic recording device, an optical disk, a magneto-optical recording medium, and a semiconductor memory. Examples of the magnetic recording device include a hard disk device (HDD), a flexible disk (FD), and a magnetic tape. Examples of the optical disc include a DVD (Digital Versatile Disc), a DVD-RAM (Random Access Memory), a CD-ROM (Compact Disc Read Only Memory), and a CD-R (Recordable) / RW (ReWritable). Magneto-optical recording media include MO (Magneto-Optical disk).
プログラムを流通させる場合には、例えば、そのプログラムが記録されたDVD、CD−ROMなどの可搬型記録媒体が販売される。また、プログラムをサーバコンピュータの記憶装置に格納しておき、ネットワークを介して、サーバコンピュータから他のコンピュータにそのプログラムを転送することもできる。 When distributing the program, for example, a portable recording medium such as a DVD or a CD-ROM in which the program is recorded is sold. It is also possible to store the program in a storage device of a server computer and transfer the program from the server computer to another computer via a network.
プログラムを実行するコンピュータは、例えば、可搬型記録媒体に記録されたプログラムもしくはサーバコンピュータから転送されたプログラムを、自己の記憶装置に格納する。そして、コンピュータは、自己の記憶装置からプログラムを読み取り、プログラムに従った処理を実行する。なお、コンピュータは、可搬型記録媒体から直接プログラムを読み取り、そのプログラムに従った処理を実行することもできる。また、コンピュータは、サーバコンピュータからプログラムが転送される毎に、逐次、受け取ったプログラムに従った処理を実行することもできる。 The computer that executes the program stores, for example, the program recorded on the portable recording medium or the program transferred from the server computer in its own storage device. Then, the computer reads the program from its own storage device and executes processing according to the program. The computer can also read the program directly from the portable recording medium and execute processing according to the program. In addition, each time the program is transferred from the server computer, the computer can sequentially execute processing according to the received program.
1 光源部
2 干渉光学系
3 位置調整機構
4 撮像部
5 演算制御部
6 干渉レンズ
7 測定対象
8 ピエゾドライバ
9 ステージドライバ
10 ピエゾステージ
11 移動ステージ
DESCRIPTION OF SYMBOLS 1 Light source part 2 Interference optical system 3 Position adjustment mechanism 4 Imaging part 5 Operation control part 6 Interference lens 7 Measurement object 8 Piezo driver 9 Stage driver 10 Piezo stage 11 Moving stage
Claims (5)
前記演算制御部は、
前記撮像部により撮像された干渉縞画像に、前記物体表面における注目点とその近傍点とを設定し、前記注目点と前記近傍点における干渉光強度をそれぞれ測定する干渉光強度測定手段と、
前記注目点と前記近傍点との高低差により生じる両干渉光強度の差分の絶対値を、前記ステージを前記高低差分移動したときの前記注目点における両干渉光強度の差分の絶対値とみなして、これを特徴量として算出する特徴量算出手段と、
前記位置調整機構により前記ステージを所定の標本点間隔ずつ移動させて順次算出された前記特徴量の分布をサンプリングするサンプリング手段と、
前記特徴量の分布から前記特徴量のピーク位置を検出し、前記特徴量がピーク位置となる前記ステージの位置を検出することにより、前記測定対象の高さを算出する高さ算出手段と、
を備えたことを特徴とする微小高さ測定装置。 A light source unit capable of irradiating a low-coherence light having a preset center wavelength, and irradiating light from the light source unit is reflected on each of the object surface to be measured and the reference surface of the reference object, and the both reflected lights interfere with each other. An interference optical system, a stage that movably supports at least one of the measurement object and the reference object, and a position adjustment mechanism that can adjust a distance between the object surface and the reference surface by driving the stage; A micro height provided with an imaging unit that captures and acquires the interference fringe image of both reflected lights, and an arithmetic control unit that measures the height of the object surface using the interference fringe image acquired by the imaging unit In the measuring device,
The arithmetic control unit is
Interference light intensity measuring means for setting an attention point and its neighboring points on the object surface to the interference fringe image imaged by the imaging unit, and measuring the interference light intensity at the attention point and the neighboring points, respectively;
The absolute value of the difference between the two interference light intensities caused by the difference in height between the attention point and the neighboring point is regarded as the absolute value of the difference between the two interference light intensities at the attention point when the stage is moved by the difference in height. , A feature amount calculating means for calculating this as a feature amount;
Sampling means for sampling the distribution of the feature values sequentially calculated by moving the stage by a predetermined sampling point interval by the position adjusting mechanism;
A height calculating means for calculating a height of the measurement object by detecting a peak position of the feature quantity from the distribution of the feature quantity, and detecting a position of the stage at which the feature quantity becomes a peak position;
A minute height measuring device characterized by comprising:
前記特徴量算出手段は、前記注目点と前記各近傍点の干渉光強度の差の絶対値が最も大きいもののみを、又は前記注目点と前記各近傍点の干渉強度から得られるビジビリティを、前記特徴量として算出すること、
を特徴とする請求項2記載の微小高さ測定装置。 The interference light intensity measuring means sets at least two points near the point of interest at each moving position of the stage,
The feature amount calculating means is configured to obtain only the largest absolute value of the difference in interference light intensity between the attention point and each neighboring point, or the visibility obtained from the interference intensity between the attention point and each neighboring point, Calculating as a feature value,
The micro height measuring apparatus according to claim 2.
前記特徴量算出手段は、前記高さ方向に隣接した前記注目点と前記各近傍点の干渉光強度の差の絶対値が最も大きいもののみを、又は前記注目点と前記各近傍点の干渉強度から得られるビジビリティを、前記特徴量として算出すること、
を特徴とする請求項1記載の微小高さ測定装置。
The interference light intensity measuring means moves the stage in the height difference height direction by the position adjusting mechanism, acquires at least three interference fringe images picked up by the image pickup unit, and includes in each interference fringe image. Measure the interference light intensity with one of the measurement points at the same position as the attention point and the other as the neighboring point,
The feature quantity calculating means only selects the one having the largest absolute value of the difference in interference light intensity between the attention point adjacent to the height direction and each neighboring point, or the interference intensity between the attention point and each neighboring point. Calculating the visibility obtained from the feature amount,
The micro height measuring apparatus according to claim 1.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2004147532A JP4357361B2 (en) | 2004-05-18 | 2004-05-18 | A micro height measurement device using low coherence interferometry |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2004147532A JP4357361B2 (en) | 2004-05-18 | 2004-05-18 | A micro height measurement device using low coherence interferometry |
Publications (2)
Publication Number | Publication Date |
---|---|
JP2005331254A JP2005331254A (en) | 2005-12-02 |
JP4357361B2 true JP4357361B2 (en) | 2009-11-04 |
Family
ID=35486028
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP2004147532A Expired - Fee Related JP4357361B2 (en) | 2004-05-18 | 2004-05-18 | A micro height measurement device using low coherence interferometry |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP4357361B2 (en) |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4554385B2 (en) * | 2005-01-27 | 2010-09-29 | 浜松ホトニクス株式会社 | Surface shape measuring method and measuring apparatus |
JP4947301B2 (en) * | 2007-06-14 | 2012-06-06 | 独立行政法人産業技術総合研究所 | Dimension measuring apparatus and dimension measuring method |
JP2008309638A (en) * | 2007-06-14 | 2008-12-25 | National Institute Of Advanced Industrial & Technology | Dimension measuring device and dimension measuring method |
JP5544679B2 (en) * | 2007-08-20 | 2014-07-09 | 富士通株式会社 | Step surface shape measuring method and measuring device |
JP5188127B2 (en) * | 2007-09-14 | 2013-04-24 | キヤノン株式会社 | Absolute position measuring apparatus and measuring method |
JP5517753B2 (en) | 2010-06-03 | 2014-06-11 | キヤノン株式会社 | Interference measurement device |
JP5663758B2 (en) * | 2010-08-17 | 2015-02-04 | 株式会社ミツトヨ | Shape measuring method and shape measuring apparatus |
CN103975220A (en) * | 2011-12-07 | 2014-08-06 | 柯尼卡美能达株式会社 | Shape-measuring device |
-
2004
- 2004-05-18 JP JP2004147532A patent/JP4357361B2/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
JP2005331254A (en) | 2005-12-02 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP4782958B2 (en) | Surface shape measuring apparatus and method, program, and storage medium | |
JPH07503315A (en) | Method and apparatus for calibrating intensity and determining order of interference fringes for small spacing interferometry | |
JP5747180B2 (en) | Shape measuring method and shape measuring apparatus | |
US7274466B2 (en) | Method and apparatus for measuring dynamic configuration surface | |
JP2018528397A (en) | Interference roll-off measurement using static fringe pattern | |
JP4357361B2 (en) | A micro height measurement device using low coherence interferometry | |
JP5544679B2 (en) | Step surface shape measuring method and measuring device | |
JP4357360B2 (en) | Surface shape measuring method and surface shape measuring apparatus | |
JP3816402B2 (en) | Surface shape measuring apparatus and surface shape measuring method | |
CN109195735A (en) | Optical drift corrects system and method | |
JP3936167B2 (en) | Surface measuring device | |
Guo et al. | A nanomeasuring machine based white light tilt scanning interferometer for large scale optical array structure measurement | |
JPH08327327A (en) | Method and apparatus for measuring height of bump | |
JP2021060311A (en) | Analyzer, analysis method, interference measuring system, and program | |
JP4821300B2 (en) | Minute height measuring method, measuring apparatus, and measuring program | |
JP4177188B2 (en) | Method, apparatus and optical element for simultaneous measurement of dynamic shape and dynamic position | |
US6906806B2 (en) | Method and apparatus for measuring motion | |
JP2008241499A (en) | Interference measuring instrument, and focus regulation method | |
JP2003014433A (en) | Shape measuring apparatus, control device for shape measuring apparatus, and control program for shape measuring apparatus | |
Heikkinen et al. | Self-calibrated defocused speckle imaging for remote surface motion measurements | |
Tsukahara | Three-dimensional measurement technologies for advanced manufacturing | |
JP3863408B2 (en) | Magnetic head slider inspection device | |
JP2006119099A (en) | Device for measuring displacement of periodically movable object | |
JP5257166B2 (en) | Optical component measuring method and apparatus | |
JPH07190737A (en) | Shearing interference measuring method and shearing interferometer |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20070409 |
|
A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20090602 |
|
A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20090609 |
|
A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20090714 |
|
TRDD | Decision of grant or rejection written | ||
A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20090804 |
|
A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20090804 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120814 Year of fee payment: 3 |
|
R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120814 Year of fee payment: 3 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130814 Year of fee payment: 4 |
|
LAPS | Cancellation because of no payment of annual fees |