JP2006133202A - Method for detecting central position of measuring object - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and device for detecting the central position of a measuring object, capable of determining the center of the measuring object without using a CCD camera or needing complicated arithmetic processing. <P>SOLUTION: A measuring object having four sides, for example, is irradiated with light to determine, with respect to the vertical sides, three points of two points on one side and one point of the other side. The inclination from a reference line is determined from the two points of the one side of the vertical sides. Thereafter, the interval between the two point of the one side is calculated. With respect to the horizontal sides, three points are determined similarly to the vertical sides to determine the inclination and the like. Consequently, the center of the measuring object can be calculated from the inclination and interval for the three points of the vertical sides and the inclination and interval for the three points of the horizontal sides. The slippage (rotation error) from the refference position of this quadrilateral can be determined from the center of the quadrilateral. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for detecting the center position of an object to be measured provided on a substrate, and more particularly to a technique for aligning a substrate or positioning marks.

On the substrate, two positioning marks (hereinafter referred to as a first origin mark and a second origin mark) are printed as alignment reference points. The first origin mark and the second origin mark have a quadrangular shape. In general, these positioning mark images are captured by a CCD, and the angle of the substrate placement and the position of the positioning mark are detected from the CCD image.
For example, as described in Patent Document 1, images of these positioning marks are captured by CCD cameras respectively disposed at positions of a first origin mark and a second origin mark provided on the substrate. Next, these positioning mark images are binarized. Thereafter, the contour of the mark is extracted from the binarized positioning mark data, and the total length of each contour is obtained. Next, an outline whose length falls within a predetermined allowable range is selected as a reference pattern. And the technique of detecting the position (coordinate) of the center of a pattern by the weighted average of this reference pattern is disclosed.

JP-A-6-74714

However, the method described in Patent Document 1 requires a CCD camera that captures an image of a positioning mark.
In the case of a CCD camera, complicated arithmetic processing such as binary processing or weighted averaging of image data captured by the CCD is required.
Further, when a CCD camera or the like is used, alignment for imaging the measurement object is necessary at the time of initial setting, and accuracy of the alignment is also required.

The present invention has been made in order to solve the above-described problem. In order to obtain the center of the origin mark, a CCD camera for capturing an image of a positioning mark is not required, and a complicated calculation process is not required. An object of the present invention is to provide a method for detecting the center position of an object.
It is another object of the present invention to provide a method for detecting the center position of a measurement object that does not require alignment of the measurement object when a CCD camera is used.

According to the first aspect of the present invention, the measurement object for detecting the center of the measurement object, which is a rectangle or a square mounted on the base plane, is detected using light that linearly scans within the base plane. A center position detecting method for obtaining two points X2 and X3 on one side and one point X1 on the other side of the vertical side of the rectangle or square , and between the two points X2 and X3 on the one side A step of obtaining the length δ of the Y component, a step of obtaining a slope α1 of the vertical side with respect to a reference line provided on the base plane from the two points X2 and X3 on the side, and a side of the rectangle or square on the side A step of obtaining two points Y2, Y3 and one point Y1 on the other side, a step of obtaining the length δ of the X component between the two points Y2, Y3 on the one side, and a reference from the two points Y2, Y3 on the one side A step of obtaining a slope β1 from the line; 3 points 3 points X1, X2, X3 and the lateral edges of said vertical side Y1, Y2, by Y3 and preset in advance with the reference point coordinates (XV1, YV1), the measured object based on the following equation Calculating the center (XC1, YC1) of the measurement object.
XC1 = (Y1 + Y2-2YV1 + δ + α1X1 + α1X2−2β1XV1 + β1δ) / 2 (α1-β1)
YC1 = (α1Y1 + α1Y2-2β1YV1 + β1δ + α1β1X1 + α1β1X2-2α1β1XV1 + α1β1δ) / 2 (α1-β1)

The measurement object having four sides is not limited, and may be, for example, a substrate or an alignment mark printed on the substrate.
Further, the base plane is not limited. When the measurement target is a substrate, a desk (stage) on which the substrate is placed becomes the base plane. Alternatively, when the measurement object is an origin mark provided on the substrate, the substrate is the base plane. The substrate may be, for example, a semiconductor chip or a glass substrate used for a liquid crystal display. Furthermore, the lengths of the vertical and horizontal sides of the object to be measured are not limited.
As the material of the measurement object, silver, aluminum, gold, copper, rhodium, a compound thereof, and the like are preferable when the reflectance of the base plane is low. When the reflectance of the base plane is high, chromium, a compound thereof, an organic film, or the like is preferable.
The means for obtaining the three points of the vertical side and the horizontal side is obtained by irradiating light. The light may be, for example, a light emitting diode or a semiconductor laser. Alternatively, X-rays may be used. The detection means for detecting the luminance (reflected light) of the light is not limited, and for example, PSD (Position Sensitive Detector) or PD ( Photo Diode ) is used.
First, the three points on the vertical side may be obtained, and thereafter, the three points on the horizontal side may be obtained, or the horizontal side may be obtained and then the vertical side may be obtained.
The center of the quadrilateral may be the center of gravity or the centroid.

In the method for detecting the center position of the measurement object according to claim 1, first, the measurement object consisting of a rectangle or a square is irradiated with light, and the vertical sides are two points on one side separated by a specified length. And 3 points on the other side. Next, an inclination from the reference line is obtained from two points on one side of the vertical side. Further, the distance between the two points in the scanning direction is obtained based on the intersection of the measurement object and the scanning line. Next, with respect to the horizontal side, three points are obtained in the same manner as the vertical side, and an inclination or the like is obtained. Accordingly, the center of the measurement object can be calculated from the inclination of the vertical side and the distance between the two points (distance of Y component) and the inclination of the horizontal side and the distance between the two points (distance of the X component). it can. Then, by comparing the center of the two objects to be measured arranged on the base plane with the reference position when there is no error, the displacement (rotation error) of the substrate with respect to the reference axis can be obtained.

According to the present invention, light is irradiated to a measurement object made of a rectangle or a square . By this irradiation, three points on the vertical side, that is, two points on one side and one point on the other side that are separated from each other by a specified length , are obtained . Next, an inclination from the reference line is obtained from two points on one side of the vertical side. Further, the distance between the two points in the scanning direction is obtained based on the intersection of the measurement object and the scanning line. Next, regarding the horizontal side, the inclination and the like are obtained for three points in the same manner as the vertical side. Accordingly, the center position of the measurement object is calculated from the inclination of the vertical side and the distance between two points (distance of Y component) and the inclination of the horizontal side and the distance between two points (distance of X component). Can do. The center position can be calculated by obtaining several points even for a measurement object having a circular shape.
Then, by comparing the center of the two objects to be measured arranged on the base plane with the reference position when there is no error, the displacement (rotation error) of the substrate with respect to the reference axis can be obtained. Therefore, complicated arithmetic processing by a conventional CCD camera is unnecessary. Further, there is no need for alignment as in a CCD camera, and there is no need for alignment accuracy.

A first embodiment according to the present invention will be described below with reference to FIGS.
First, a center position detection device for a measurement object will be described.
As shown in FIG. 1, the position detection apparatus according to the present embodiment is provided with three support members 15 on the stage 14 in the X-axis direction. The X stage 1 that reciprocates in the X-axis direction is disposed on the three support members 15. A first linear scale 2 for measuring the moving distance (X axis) of the X stage 1 is disposed on the side of the X stage 1.
Two support members 16 are disposed in the Y-axis direction on the X stage 1, and the Y stage 3 that can reciprocate in the Y-axis direction is provided on the support member 16. A second linear scale 4 for measuring the moving distance (Y axis) of the Y stage 3 is disposed on the side of the Y stage 3.
Then, the substrate 7 is mounted on the Y stage 3. Positioning marks (first origin mark 5 and second origin mark 6) each having a quadrilateral, which is a measurement object, are arranged on the substrate 7 diagonally. Thereby, the substrate 7 is mounted on the X stage 1 and the Y stage 3 so as to be reciprocable in the X-axis or Y-axis direction.
Further, a luminance detector 8 is provided above the substrate 7. The luminance detector 8 is provided with an irradiation unit 10 that emits light by a light emitting diode and a light receiving unit 9 that receives reflected light of the light emitting diode. An XY stage controller 12 that reciprocates the X stage 1 and the Y stage 3 is provided. Further, a luminance detector controller 11 that is connected to the luminance detector 8 and detects the luminance of the light received by the light receiving unit 9 is provided. Further, an arithmetic device 13 is connected to the XY stage controller 12 and the luminance detector controller 11 via a communication line.

Next, a position detection method for obtaining the center of the quadrilateral using the position detection device will be described.
As shown in FIG. 1, first, the substrate 7 is placed on the Y stage 3. Next, the light of the light emitting diode of the irradiation unit 10 scans above the first origin mark 5 and the second origin mark 6 by reciprocating the XY stage in the XY direction. Then, the luminance of the reflected light of the light emitting diode is measured by the light receiving unit 9 of the luminance detector 8. The brightness of the reflected light measured by the light receiving unit 9 is measured as an analog signal. Then, this analog signal is transmitted to the luminance detector controller 11. Next, the luminance detector controller 11 amplifies the analog signal of the light measured by the light receiving unit 9 and then transmits the amplified analog signal to the arithmetic device 13 via the communication line. The arithmetic device 13 converts the transmitted analog signal into a digital signal, and determines the difference between the luminance of the base (Y stage 3) and the luminance of the substrate 7 based on the digital signal.
On the other hand, position signals of the first linear scale 2 of the X stage 1 and the second linear scale 4 of the Y stage 3 are transmitted to the arithmetic device 13 via the XY stage controller 12 as needed. Therefore, the intersection point can be obtained from this position signal and the difference between the luminance of the base substrate 7 and the luminance of the first origin mark 5 and the second origin mark 6. And this intersection is registered into the arithmetic unit 13 as the value of the intersection coordinates. Then, the arithmetic device 13 uses the registered value to calculate the center of the origin mark based on the stored arithmetic expression. Thereafter, an error amount in the rotation direction of the substrate 7 is calculated using the centers of the first origin mark 5 and the second origin mark 6. The calculated error amount is fed back from the arithmetic unit 13 to the XY stage controller 12 as a correction value. Then, it is possible to cancel (correct) the rotation error of the substrate 7 that occurs at the time of attachment or the like.

Next, a first method for detecting the center of the origin mark printed on the substrate 7 will be described. FIG. 2 shows the substrate 7 on which the first origin mark 5 and the second origin mark 6 are printed diagonally, and a dotted line indicates a state where there is no position length with respect to the coordinates of the pattern data to be drawn. That is, the center of the origin mark indicated by the dotted line coincides with the design value. However, in practice, the first origin mark 5 and the second origin mark 6 cause a rotation error with respect to the design value as indicated by the solid line due to the substrate shape error or mounting error. The rotation error causes θe.
This detection method aims to generate a pattern accurately at a desired location on the substrate by detecting such a rotation error and feeding it back to the drawing data.
This detection method is characterized in that the actual origin mark coordinates are detected and calculated using design data as a reference value. That is, the actual center of the mark (XC1, YC1) is calculated by detecting the necessary point on the actual first mark with reference to the designed first origin mark center (XV1, YV1). Then, based on the design center of the second origin mark (XV2, YV2), a point on the actual second mark is detected and the center of the actual mark (XC2, YC2) is calculated. To do.
FIG. 3 shows a detection method for detecting the center of the origin mark when the origin mark has an error only in the rotation direction. The rotation error is also included in the origin mark. For this reason, in order to determine the center of the origin mark, it is necessary to consider the inclination of the origin mark itself. Actually, the inclination of the line segment AB is first obtained, and then a line is drawn parallel to the line segment AB from the midpoint G of the line segment EF that intersects the origin mark during the X-axis direction scan. Next, after obtaining the slope of the line segment AD in the same way, when a line is drawn parallel to the line segment AD from the midpoint J of the line segment HI that intersects the origin mark during scanning in the Y-axis direction, the intersection is the origin mark. Center coordinates (XC, YC).

Next, a specific procedure and calculation method for detecting the center of the substrate 7 having a rotation error will be described.
Here, in detecting the intersection point, the detector is scanned in the X-axis direction from the outside to the inside of the origin mark. However, the same result can be obtained by scanning from the inside to the outside of the origin mark. The light of the light emitting diode is irradiated onto the first origin mark 5 along the straight line Y = YV1−δ / 2, P1 and P2 are detected, and the first origin along the straight line Y = YV1 + δ / 2. Irradiate the mark 5 to detect P3. The X coordinates of the obtained intersections P1, P2, and P3 are X1, X2, and X3, respectively. The displacement amount of X2 and X3 with respect to the Y-axis direction is δ. Thereby, the inclination α1 of the first origin mark 5 with respect to the X axis can be calculated.
α1 = δ / (X3−X2)
Similarly, the detector is scanned along the line X = XV1-δ / 2 from the outside to the inside of the first origin mark 5 to detect P4 and P5, and to the line X = XV1 + δ / 2. Then, the detector is scanned along to detect P4 and P5. The Y coordinates of the obtained intersections P4, P5, and P6 are Y1, Y2, and Y3 , respectively. The displacement amount of Y2 and Y3 with respect to the X-axis direction is δ. Thereby, the inclination β1 of the first origin mark 5 with respect to the Y axis can be calculated.
β1 = δ / (Y3-Y2)
Next, the center of the first origin mark 5 is calculated by passing through the midpoint of the line segment P1P2, passing through the straight line having the inclination α1 and the midpoint of the line segment P4P5, and connecting the straight line having the inclination β1.
The midpoint (Xm, Ym) of the line segment P1P2 is expressed by the following equation.
Xm = (X1 + X2) / 2
Ym = YV1-δ / 2
Therefore, a straight line passing through (Xm, Ym) with an inclination α1 is as follows.
y = α1x + YV1-δ / 2-α1 (X1 + X2) / 2 --- (1)
Similarly, the midpoint (Xn, Yn) of the line segment P4P5 is expressed by the following equation.
Xn = XV1-δ / 2
Yn = (Y1 + Y2) / 2
Therefore, a straight line passing through (Xn, Yn) with an inclination β1 is as follows.
y = β1x + (Y1 + Y2) / 2−β1XV1 + β1δ / 2 −−−− (2)
Therefore, if the coordinates and inclination of the intersection are used, the center coordinates (XC1, YC1) of the first origin mark can be obtained as follows by combining the equations (1) and (2).
XC1 = (Y1 + Y2-2YV1 + δ + α1X1 + α1X2−2β1XV1 + β1δ) / 2 (α1-β1)
YC1 = (α1Y1 + α1Y2-2β1YV1 + β1δ + α1β1X1 + α1β1X2-2α1β1XV1 + α1β1δ) / 2 (α1-β1)

Next, the second origin mark 6 is similarly obtained. The detector is scanned along Y = YV2-δ / 2 and Y = YV2 + δ / 2 from the outside to the inside of the second origin mark 6, and the X coordinates of the obtained intersection points P7, P8, P9 are respectively set. , X4, X5, X6, the inclination α2 of the second origin mark 6 with respect to the X axis can be calculated by the following equation.
α2 = δ / (X6-X5)
Similarly, the detector is scanned along X = XV2-δ / 2 and X = XV2 + δ / 2 from the outside to the inside of the second origin mark 6, and the obtained intersections P10, P11, P12 are obtained. When the Y coordinate is Y4, Y5, Y6, the inclination β2 of the second origin mark 6 with respect to the Y axis can be calculated by the following formula.
β2 = δ / (Y6-Y5)

Next, the center of the second origin mark 6 is calculated by passing through the midpoint of the line segment P7P8, passing through the straight line having the inclination α2 and the midpoint of the line segment P10P11, and connecting the straight line having the inclination β2.
The midpoint (Xp, Yp) of the line segment P7P8 is expressed by the following equation.
Xp = (X4 + X5) / 2
Yp = YV2-δ / 2
Therefore, a straight line passing through (Xp, Yp) with an inclination α2 is as follows.
y = α2x + YV2-δ / 2-α2 (X4 + X5) / 2 --- (3)
Similarly, the midpoint (Xq, Yq) of the line segment P10P11 is expressed by the following equation.
Xq = XV1-δ / 2
Yq = (Y1 + Y2) / 2
Therefore, a straight line passing through (Xq, Yq) with an inclination β1 is as follows.
y = β2x + (Y4 + Y5) / 2−β1XV1 + β1δ / 2 −−−− (4)
Therefore, if the coordinates and inclination of the intersection are used, the second origin mark 6 center coordinates (XC2, YC2) can be obtained as follows by combining the equations (3) and (4).
XC2 = (Y4 + Y5-2YV2 + δ + α2X4 + α2X5-2β2XV2 + β2δ) / 2 (α2-β2)
YC2 = (α2Y4 + α2Y5-2β2YV2 + β2δ + α2β2X4 + α2β2X5-2α2β2XV2 + α2β2δ) / 2 (α2-β2)
From the above, when the error in the rotation direction of the substrate 7 is θe,
θe = − (tan ⁻¹ (XC1−XC2) / (YC1−YC2) −tan ⁻¹ (XV1−XV2) / (YV1−YV2))
(When the clockwise direction is positive) .

  FIG. 5 is a graph showing the result of actual measurement using the present invention. Captures luminance signal of 5 mm square aluminum thin film vapor-deposited and patterned on glass substrate 7 using PSD as a semiconductor laser and light-receiving element as an irradiation device, and interlocks it with an XY stage equipped with a position detector (linear scale) This shows the variation when the coordinates of the intersection of the contour line of the first origin mark 5 and the scanning line are detected. As a result of 40 measurements, it was found that all were within ± 1 μm. In addition, regarding the detection of the rotation error, when measured and calculated by the present invention using the substrate 7 having a known rotation error by actual measurement, the value calculated with the effective number of digits of two decimal places is 5.67 deg. The error of the set value with respect to 5.67 deg was found to be 0.01 deg or less.

次に、図１０に示すように、２点Ｐ１３（Ｘ１３、Ｙ１３）、Ｐ１４（Ｘ１４、Ｙ１４）間の中点ＭからＹ軸と平行に線を引き、中心ＯからＸ軸に引いた線との交点をＮとする。これによりＯＭＮの直角三角形が形成される。ＯＭＮで形成される角度をθとすると、線分ＯＮの長さは以下の式で求められる。

また、線分ＭＮの長さは以下の式で求められる。

２点Ｐ１３（Ｘ１３、Ｙ１３）、Ｐ１４（Ｘ１４、Ｙ１４）は、中心Ｏに対してＸＹの正方向に存在している。これにより、第１の原点マーク５の中心の座標（ＸＣ１、ＹＣ１）は、それぞれ、次式により算出することができる。
ＸＣ１＝（Ｘ１３＋Ｘ１４）／２−ＯＮ
ＹＣ１＝（Ｙ１３＋Ｙ１４）／２−ＭＮ
以上の結果、第１の原点マーク５の中心の座標（ＸＣ１、ＹＣ１）は、

Next, a description will be given of a first method of detecting the center of the origin mark which is a circular origin mark printed on the substrate 7. In the present embodiment, the center position is obtained by detecting the first origin mark 5 and the second origin mark 6 whose radius R is known.
FIG. 6 is a plan view showing a substrate having no rotation error and a substrate having a rotation error, in which the first origin mark 5 and the second origin mark 6 are printed diagonally. The center coordinates of the first origin mark 5 of the substrate 7 having no rotation error are (XV1, YV1), and the center coordinates of the second origin mark 6 are (XV2, YV2). On the other hand, the center coordinates of the first origin mark 5 of the substrate 7 having the rotation error are (XC1, YC1), and the center coordinates of the second origin mark 6 are (XC2, YC2).
FIG. 7 is a plan view showing a scanning path of irradiation light for detecting the center of a circular origin mark based on this embodiment. As shown in FIG. 7, first, the irradiation light is temporarily positioned at the start position based on the design value of the first origin mark 5. Next, light is scanned in the −Y direction to detect a point P13 on the circumference. After detecting the point P13, the scanning is advanced in the predetermined distance −Y direction. Next, the scanning direction is changed by 90 degrees, and light is scanned in the + X direction. Then, a point P14 on the circumference is detected. The coordinates of the points P13 and P14 on the circumference obtained by scanning the light in an L shape in this way are (X13, Y13) and (X14, Y14), respectively. The radius of the first origin mark 5 is R.
Here, as shown in FIG. 9, a line connecting two points P13 (X13, Y13) and P14 (X14, Y14) obtained by scanning of the irradiation light is drawn. Then, the middle point of this line is set as M, and a line segment OM connecting to the center O of the first origin mark 5 is drawn. Thereby, a right triangle of MOP14 is formed, and an angle formed by MOP14 is γ. In addition, a half length of the line segment P13P14 is a. Then, the length of the line segment OM is calculated | required with the following formula | equation.

Next, as shown in FIG. 10, a line is drawn parallel to the Y axis from the midpoint M between the two points P13 (X13, Y13) and P14 (X14, Y14), and is drawn from the center O to the X axis. Let N be the intersection of. This forms an OMN right triangle. When the angle formed by OMN is θ, the length of the line segment ON can be obtained by the following equation.

Moreover, the length of the line segment MN is calculated | required with the following formula | equation.

Two points P13 (X13, Y13) and P14 (X14, Y14) exist in the positive direction of XY with respect to the center O. Thereby, the coordinates (XC1, YC1) of the center of the first origin mark 5 can be calculated by the following equations, respectively.
XC1 = (X13 + X14) / 2-ON
YC1 = (Y13 + Y14) / 2-MN
As a result of the above, the coordinates (XC1, YC1) of the center of the first origin mark 5 are

同様にして第２の原点マーク６の中心を求めて、その座標をＸＣ２、ＹＣ２とすると、基板７の回転方向の誤差θｅは、次式のようになる。
なお、式１６および式１８に示すように、（Ｘ１＋Ｘ２）／２項の後の±は、点Ｍおよび点Ｎが点Ｏより正方向または負方向のいずれかによって、線分ＯＮおよび線分ＭＮを減算したり加算したりしている。
θｅ＝ｔａｎ^−１（ＸＣ１−ＸＣ２）／（ＹＣ１−ＹＣ２）−ｔａｎ^−１（ＸＶ１−ＸＶ２）／（ＹＶ１−ＹＶ２）
最初から半径Ｒが判明している原点マークにあっては、この原点マークの円周上の２点を求めればよい。この結果、光の走査距離も短くてすみ、しかも短時間で原点マークの中心を検出することができる。 FIG. 8 is a plan view showing a scanning path different from that shown in FIG. First, the point P15 is detected by scanning light in the -Y direction, and thereafter, the process is the same as in FIG. Thereafter, the scanning direction is changed by 90 degrees, light is scanned in the −X direction, and a point P16 is detected. The coordinates of the points P15 and P16 on the circumference obtained by scanning the light in an inverted L shape in this way are (X15, Y15) and (X16, Y16), respectively. The radius of the first origin mark 5 is R.
In this case, as shown in FIG. 11, the coordinates (XC1, YC1) of the center of the first origin mark 5 are obtained by adding the line segment ON to the X coordinate of the midpoint M between the points P15 and P16, It can be obtained by subtracting the line segment MN. Therefore, by this, the coordinates (XC1, YC1) of the center of the first origin mark 5 can be calculated by the following equations, respectively.
XC1 = (X13 + X14) / 2 + ON
YC1 = (Y13 + Y14) / 2-MN
Thereby, the center coordinates (XC1, YC1) of the first origin mark 5 can be calculated by the following equations, respectively.

Similarly, when the center of the second origin mark 6 is obtained and the coordinates thereof are XC2 and YC2, the error θe in the rotation direction of the substrate 7 is expressed by the following equation.
As shown in Expression 16 and Expression 18, ± after the (X1 + X2) / 2 term indicates that the line segment ON and the line segment MN depend on whether the point M and the point N are in the positive direction or the negative direction from the point O. Are subtracted or added.
θe = tan ⁻¹ (XC1−XC2) / (YC1−YC2) −tan ⁻¹ (XV1−XV2) / (YV1−YV2)
For an origin mark whose radius R is known from the beginning, two points on the circumference of the origin mark may be obtained. As a result, the light scanning distance can be short, and the center of the origin mark can be detected in a short time.

Next, a second method of detecting the center of the origin mark which is a circular origin mark printed on the substrate 7 will be described.
FIG. 12 is a plan view showing a scanning path of irradiation light for detecting the center of a circular origin mark based on the third embodiment. As shown in FIG. 12, first, the irradiation light is positioned at the start position based on the design value of the origin mark 1. Next, the irradiation light is scanned until it crosses the origin mark in the + X direction, and points P17 and P18 are detected. Then, after detecting the point P18, the irradiation light is further sent in the + X direction and moved in the −Y direction by a distance that does not exceed the diameter of the circular origin mark 1 (actually about a radius). Thereafter, the irradiation light is scanned in the −X direction until the point P19 is detected. The coordinates of the points P17, P18, and P19 on the circumference thus obtained are (X17, Y17), (X18, Y18), and (X19, Y19), respectively.
Here, as shown in FIG. 14, the intersection of the vertical bisector of the line segment P17P18 and the vertical bisector of the line segment P18P19 becomes the center O of the first origin mark 5. Thereby, the equation of the line segment P17P18 is obtained as follows.
X = (X17 + X18) / 2
On the other hand, the equation of the line segment P18P19 is a straight line having an inclination of (X18-X19) (Y19-Y18) and passing through the midpoint ((X18 + X19) / 2, (Y18 + Y19) / 2) of this line segment. Therefore, it is expressed as the following equation.
^{Y = (X 18- X 19)} (Y19-Y18) X + (X18 2 -X19 2 + Y18 2 -Y19 2) / 2 / (Y18-Y19)
By making the above two equations simultaneous, the center of the first origin mark 5, (XC1, YC1), can be obtained by the following equation.
XC1 = (X17 + X18) / 2
YC1 = ((X18−X19). (X17 + X18) + Y19 ² −Y18 ² + X19 ² −X18 ² ) / 2 (Y19−Y18)
By the above method, the center of the second origin mark 6 can be similarly obtained.

FIG. 13 is a plan view showing a case where the scanning path is different from FIG. First, the irradiation light is temporarily positioned at the start position based on the design value of the first origin mark 5. Next, the irradiation light is scanned until it crosses the first origin mark 5 in the −Y direction, and the points P20 and P21 are detected. Then, after detecting the point P21, the irradiation light is scanned in the −Y direction. Next, it is moved by a distance in a range not exceeding the diameter of the circular first origin mark 5 in the + X direction (actually about a radius). Thereafter, the irradiation light is scanned in the Y direction until the point P22 is detected. The coordinates of the points P20, P21, and P22 thus obtained are (X20, Y20), (X21, Y21), and (X22, Y22), respectively. Thereby, the center (XC1, YC1) of the first origin mark 5 can be obtained using the coordinates of the three points by the following equation.
XC1 = ((Y21−Y22). (Y20 + Y21) + X22 ² −X21 ² + Y22 ² −Y21 ² ) / 2 (X22−X21)
YC1 = (Y20 + Y21) / 2
The present embodiment is effective when the radius of the circular origin mark whose radius R is unknown or the two origin marks are different from each other.

Next, a third method for detecting the center position of a circular origin mark printed on the substrate 7 will be described.
FIG. 15 is a scanning path of irradiation light showing the third embodiment. First, the irradiation light is temporarily positioned at the start position based on the design value of the first origin mark 5. Next, two points P23 and P24 on the circumference are detected by traversing the circumference while scanning the irradiation light in the -Y direction. Next, two points P25 and P26 on the circumference are detected by traversing the circumference while scanning the irradiation light in the + X direction. The coordinates of the four points P23, P24, P25, and P26 thus obtained are (X23, Y23), (X24, Y24), (X25, Y25), and (X26, Y26), respectively. Thereby, the center (XC1, YC1) of the first origin mark 5 can be obtained by the following equation. By the above method, the center of the second origin mark 6 can be similarly obtained.
XC1 = (X25 + X26) / 2
YC1 = (Y23 + Y24) / 2
In FIG. 15, scanning is started from the Y axis, but the center of the first origin mark 5 can be obtained even when scanning is started from the X axis.
In the present embodiment, the calculation formula for obtaining the center is simpler than in the second or third embodiment having the circular shape.

The method for detecting the center position of the measurement object and the apparatus according to the present embodiment scan light at a high speed in a wide range as temporary detection (rough scan process), and then as main detection (precision scan process), That is, the light is scanned at a low speed in a narrower range than the provisional detection.
As the detection resolution of the XY stage becomes higher, the signal processing time of the linear scale mounted on the stage becomes a problem. The increase in the processing time imposes a restriction on the moving speed of the stage and increases the detection time of the origin mark. In this embodiment, this problem is solved by combining provisional detection and main detection. Hereinafter, the detection method of this embodiment will be described.
First, the provisional detection method will be described with reference to FIG.
FIG. 16 shows a light scanning path for provisional detection. First, light is scanned in parallel with the X axis in the negative direction of the X axis from the scanning start point. Then, an intersection X01 between the light and the line segment AB is detected. At this time, the distance from the scanning start point where the light scans to the intersection X01 with the line segment AB is 3 mm. Next, light is scanned in the negative direction of the X axis in parallel with the X axis, and an intersection X02 between the light and the line segment CD is detected. At this time, the scanning distance of light from the intersection point X01 to the intersection point X02 is 5 mm.
Thereafter, the light is scanned 1 mm in the positive direction of the Y axis. Next, the light is scanned 3 mm in the positive direction of the X axis in parallel with the X axis, and the intersection X03 of the light and the line segment CD is detected. Then, after passing the light through the intersection point X03 and scanning a predetermined distance (0.5 mm), the provisional detection is completed. Note that the scanning speed of light at the time of provisional detection is constant (10 mm / s).

Next, the detection method will be described with reference to FIG.
As shown in FIG. 17, first, light is scanned in the negative direction of the X axis from the scanning start point at a scanning speed of 1 mm / s. And the intersection X1 of light and line segment AB is detected. The scanning distance of light from the scanning start point to X1 at this time is 0.5 mm. Next, light is scanned in the negative direction of the X axis from the intersection point X1 to a distance of 4.5 mm at a scanning speed of 10 mm / s. Thereafter, the scanning speed is lowered to 1 mm / s, and the intersection X2 between the light and the line segment CD is detected.
Next, light is scanned 1 mm in the positive direction of the Y axis at a scanning speed of 10 mm / s. Thereafter, light is scanned in the positive direction of the X axis in parallel with the X axis at a scanning speed of 1 mm, and the intersection X3 of the light and the line segment CD is detected to complete the main detection.
On the other hand, as shown in FIG. 18, the conventional method for detecting an intersection is substantially the same as the present detection method. However, a sufficient scanning distance is required to reduce measurement errors and the like. Also, as described above, in order to perform position detection with high resolution, the scanning speed must be reduced. It takes a very long time to detect the origin mark under such conditions. For example, if the origin mark width is 5 mm, the scanning distance is 3 mm, the moving distance in the Y-axis direction is 1 mm, the scanning speed is 1 mm / sec, and the feed speed is 10 mm / sec, the time required to detect the intersection is 9.6 sec. become.
Since the time required for scanning according to this example is 4.25 sec, it has been found that the scanning time can be reduced to half or less compared to the conventional method.

The measurement object center position detection method and apparatus thereof according to the present embodiment are shown for a circular origin mark with respect to the measurement object center position detection method and apparatus thereof according to Embodiment 5 described above. .
First, a method for detecting the center position of the origin mark which has only the main detection will be described with reference to FIG.
The irradiation light starts from the scanning start point outside the origin mark, and approaches the origin mark. Then, scanning is performed across the origin mark in the Y-axis direction. Thereafter, the irradiation light is sent from the Y-axis direction by a necessary distance in the X-axis direction. Next, the irradiation light is approached from the outside of the origin mark in the X-axis direction, and scanning is performed so as to cross the origin mark.
In actual scanning, the coordinates of the origin mark are estimated from the design value. However, there may be an error between the design value and the actual position of the origin mark due to variations in the process of forming the origin mark pattern or errors in attaching the origin mark to the substrate. Therefore, it is necessary to consider this error (process margin).
In FIG. 19, the origin mark position is indicated by a solid line when there is no error (design value), and a dotted line when there is an error. Here, the range in which the origin mark having an error as indicated by the dotted line can be scanned is empirically set to ± 3 mm. If the diameter of the origin mark is 5 mm, the uniaxial scanning distance is a maximum of 11 mm. As a result, from FIG. 19, the scanning distance for the main detection is 22 mm and the feed is 7.8 mm. When the main detection speed is 1 mm / s and the feed speed is 10 mm / s, the time required to scan the whole is 22.8 seconds.

Next, a method for detecting the center position of a circular origin mark having provisional detection and main detection will be described with reference to FIG.
In FIG. 20, it is assumed that an error from the design value occurs at the position of the origin mark. First, provisional detection (rough scan process) is performed. The irradiation light starts from the scanning start point outside the origin mark, and approaches the origin mark. Then, scanning is performed across the origin mark in the Y-axis direction. Thereafter, the irradiation light is sent from the Y-axis direction by a necessary distance in the X-axis direction. Next, the irradiation light is approached from the outside of the origin mark in the X-axis direction, and scanning is performed so as to cross the origin mark. The feed rate at the time of this temporary detection is constant at 10 mm / s. For example, the method of the fourth embodiment is used to detect the center position at the time of provisional detection.
Next, main detection (precise scanning process) is performed. The irradiation light is sent in the X-axis direction based on the center position obtained by the provisional detection. Then, the irradiation light is approached from the outside of the origin mark in the X-axis direction, and scanning is performed so as to cross the origin mark. The margin length at the time of scanning in this detection can be reduced to ± 0.5 mm empirically. Therefore, if the distance of the origin mark is 1 mm, the uniaxial scanning distance is a maximum of 6 mm. Thereafter, the irradiation light is sent from the X-axis direction by a necessary distance in the Y-axis direction. Next, the irradiation light is made to approach from the outside of the origin mark in the Y-axis direction, and scanning is performed so as to cross the origin mark. The feed rate during this main detection is constant at 1 mm / s. For example, the method of the fourth embodiment is used for the detection of the center position during the main detection.
As shown in FIG. 20, the scanning distance at the time of temporary detection is 22 mm, the scanning speed at the time of temporary detection is 10 mm / s, the scanning distance at the time of main detection is 12 mm, the main detection speed at the time of main detection is 1 mm / s, If the scanning distance is 12.8 mm (7.8 mm + 5 mm) and the feeding speed is 10 mm / s, the time required to scan the whole is 15.5 seconds.
Therefore, the detection method shown in FIG. 20 can shorten the scanning time by 30% or more compared to the detection method having only the main detection shown in FIG. Although the detection accuracy in the provisional detection is slightly inferior, the center position can be detected with high accuracy as a result by combining with the main detection.

It is the perspective view which showed the structure of the position detection apparatus which concerns on Example 1 of this invention. It is a top view which shows the structure of the board | substrate which concerns on Example 1 of this invention, and the mark for alignment. It is a top view explaining one of the methods of calculating | requiring the center position of the board | substrate which concerns on Example 1 of this invention. It is a top view explaining one of the methods of calculating | requiring another center position of the board | substrate which concerns on Example 1 of this invention. It is a graph which shows the dispersion | variation in the positional accuracy which concerns on Example 1 of this invention. It is a top view which shows the structure of the board | substrate based on Example 2 of this invention, and the mark for alignment. It is a top view which shows the scanning path | route which calculates | requires the circular origin mark based on Example 2 of this invention in the center of a board | substrate. It is a top view which shows the scanning path | route different from FIG. It is a top view which shows the method of calculating | requiring the center of a board | substrate for the circular origin mark which concerns on Example 2 of this invention. It is a top view which shows the method of calculating | requiring the center of a board | substrate for the circular origin mark which concerns on Example 2 of this invention. It is a top view which shows the method of calculating | requiring the center of a board | substrate for the circular origin mark which concerns on Example 2 of this invention. It is a top view which shows the scanning path | route which calculates | requires the circular origin mark based on Example 2 of this invention in the center of a board | substrate. It is a top view which shows the scanning path | route different from FIG. It is a top view which shows the scanning path | route which calculates | requires the circular origin mark which concerns on Example 3 of this invention in the center of a board | substrate. It is a top view which shows the method of calculating | requiring the center of a board | substrate for the circular origin mark which concerns on Example 4 of this invention. It is a top view which shows the scanning path | route of the scanning means at the time of the temporary detection which concerns on Example 5 of this invention. It is a top view which shows the scanning path | route of the scanning means at the time of this detection which concerns on Example 5 of this invention. It is a top view which shows the scanning path | route of the scanning means which concerns on the past. It is a top view which shows the scanning path | route of the scanning means at the time of the temporary detection which concerns on Example 6 of this invention. It is a top view which shows the scanning path | route of the scanning means at the time of this detection which concerns on Example 6 of this invention.

Explanation of symbols

1 X stage (scanning means),
3 Y stage (scanning means),
5 First origin mark (measurement object),
6 Second origin mark (measurement object),
7 Substrate (base plane),
10 Light emitting diode (irradiation means),
13 Arithmetic unit.

Claims (7)

A method of detecting the center position of a measurement object using light that linearly scans within the base plane to detect the center of the measurement object having four vertical and horizontal sides mounted on the base plane. Because
Obtaining two points X ₂ and X ₃ on one side of the vertical side and one point X ₁ on the other side;
Obtaining a length δ of the Y component between the two points X ₂ and X _{3 on the} side;
Obtaining a slope α ₁ of the vertical side with respect to a reference line provided on the base plane from the two points X ₂ and X _{3 on the} side;
Obtaining two points Y ₂ and Y ₃ on one side of the horizontal side and one point Y ₁ on the other side;
Obtaining a length δ of the X component between the two points Y ₂ and Y _{3 on the} side;
Obtaining a slope β ₁ from the reference line from the two points Y ₂ and Y _{3 on the} one side;
The center (X _C1, Y _C1 ) of the measurement object is determined based on the following equation using the three points X ₁ , X ₂ , X _{3 on the} vertical side and the three points Y ₁ , Y ₂ , Y _{3 on the} horizontal side. And a center position detection method of the measurement object.
X _C1 = (Y ₁ + Y ₂ −2Y _{V 1} + δ + α ₁ X ₁ + α ₁ X ₂ −β ₁ X _{V 1} + β ₁ δ) / 2 (α ₁ −β ₁ )
_{Y C1 = (α 1 Y 1} + α 1 Y 2 -2β 1 Y V1 + β 1 δ + α 1 β 1 X 1 + α 1 β 1 X 2 -α 1 β 1 X V1 + α 1 β 1 δ) / 2 (α 1 - β ₁ ) A method of detecting a center position of a measurement object, which detects a center of a measurement object having a circular shape with a radius R mounted on the base plane using light that linearly scans within the base plane. ,
The light is scanned linearly and L-shaped in the X direction and Y direction, respectively, and the coordinates (X ₁ , Y ₁ ), (X ₂ , Y ₂ ) of two points on the circumference of the measurement object are obtained. Each of the processes to be sought,
A step of calculating the center (X _C1, Y _C1 ) of the measurement object based on the following equation from the coordinates (X ₁ , Y ₁ ), (X ₂ , Y ₂ ) of the two points and the radius R: , A method for detecting the center position of an object to be measured.

A method for detecting a center position of a measurement object, wherein the center of the measurement object having a circular shape mounted on the base plane is detected using light that linearly scans within the base plane,
The light is scanned linearly in the X direction and the Y direction in a U-shape, and the coordinates (X ₁ , Y ₁ ), (X ₂ , Y ₂ ) of three points on the circumference of the measurement object are measured. , (X ₃ , Y ₃ )
Based on the coordinates of the three points (X ₁ , Y ₁ ), (X ₂ , Y ₂ ), (X ₃ , Y ₃ ), the center of the measurement object (X _C1, Y _C1 And calculating the center position of the measurement object.
X _C1 = (Y ₂ −Y ₃ ) · (Y ₃ −Y ₁ ) / (2 (X ₂ −X ₃ )) + (X ₂ + X ₃ ) / 2
Y _C1 = (Y ₁ + Y ₂ ) / 2
X _C1 = (X ₁ + X ₂ ) / 2
Y _C1 = (X ₂ −X ₃ ) · (X ₃ −X ₁ ) / (2 (Y ₂ −Y ₃ )) + (Y ₂ + Y ₃ ) / 2 A method for detecting a center position of a measurement object, wherein the center of the measurement object having a circular shape mounted on the base plane is detected using light that linearly scans within the base plane,
The light is scanned linearly and crosswise in the X direction and Y direction, respectively, and the coordinates (X ₁ , Y ₁ ), (X ₂ , Y ₂ ) of the four points of the cross on the circumference of the measurement object are measured. , (X ₃ , Y ₃ ), (X ₄ , Y ₄ ),
Based on the coordinates of the four points (X ₁ , Y ₁ ), (X ₂ , Y ₂ ), (X ₃ , Y ₃ ), (X ₄ , Y ₄ ), the center of the measurement object ( X _C1, Y _C1 ), and a center position detection method for the measurement object.
X _C1 = (X ₃ + X ₄ ) / 2
Y _C1 = (Y ₁ + Y ₂ ) / 2   The points of the vertical side and the side of the quadrilateral of the measurement object and the points on the circumference of the object to be measured are the intensity of the reflected light from the measurement object and the reflected light from the base. The center position detection method of the measuring object of any one of Claims 1-4 calculated | required by the difference with intensity | strength. A rough scanning step of obtaining a vertical side and a horizontal side or a circle of a measurement object by scanning the entire base plane at a first scanning speed;
Based on this result, the sides and the vertical sides of the quadrilateral or the periphery of the circle are scanned at a second scanning speed smaller than the first scanning speed, and the points and the horizontal sides of the quadrilateral of the measurement object are scanned. A method of detecting the center position of the measurement object according to any one of claims 1 to 5, further comprising: a precise scanning step of detecting a point on the circumference or a point on the circumference. A measuring object center position detecting device for detecting the center of the measuring object mounted on the base plane in the base plane using light that linearly scans within the base plane,
Irradiating means for irradiating light to the measuring object and the base plane;
Scanning means for causing the irradiation means to scan relative to and linearly with respect to the measurement object in the base plane;
Irradiate light to the measurement object and the base on the points of the vertical side and the side of the quadrilateral of the measurement object and the points on the circumference, and from the intensity of reflected light from the measurement object and the base And calculating means for calculating the center position of the measurement object from the vertical and horizontal points of the quadrilateral or the points on the circumference of the quadrilateral. Position detection device.

Images