JP2597754B2 - Substrate rotation correction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for positioning a substrate such as a semiconductor wafer in various characteristic measuring devices such as a film thickness measuring device, and more particularly to a method for detecting a scribe line formed on a substrate. The present invention relates to a method for correcting rotation of a substrate.

[0002]

2. Description of the Related Art Generally, semiconductor measurement and inspection processes,
When positioning a substrate on which a fine pattern is formed in a semiconductor manufacturing process or the like, an enlarged image of the substrate surface is taken, and a predetermined position of an obtained image (for example, a center position of the image)
Then, the position of the substrate with respect to the image pickup means, that is, the orthogonal two-axis direction (X , Y direction) is detected, and the deviation is corrected. At this time, if there is a displacement in the rotation direction on the substrate to be aligned, accurate alignment cannot be performed only by coordinate movement in the orthogonal two-axis directions as described above. Must be corrected.

[0003] In correcting the rotation of the substrate, there is known a method of using a scribe line on the substrate as an index of the rotation correction. In such a method, a step of detecting a scribe line from an enlarged captured image of the substrate surface as a former stage and a step of calculating the direction of the scribe line in the enlarged captured image as a subsequent stage are necessary,
Conventionally, as a method of detecting a scribe line from an enlarged captured image which is a preceding stage, a method called a so-called binarization process is known.

According to this method, a multi-gradation image obtained by photographing the surface of a substrate is converted into a binary image by setting a gradation value set by, for example, a method called a mode method as a threshold value, so that a scribe in the image is converted. This is to detect a line.

Hereinafter, a conventional method for detecting scribe lines will be described with reference to FIGS. FIG. 11 is an enlarged captured image of a part of the substrate surface (the area where the scribe lines intersect), in which SX is a scribe line in the X direction and SY is a scribe line in the Y direction.

In the so-called mode method, when the tone value histogram of a captured image as shown in FIG. 11 shows bimodality as shown in FIG. A scribe line is detected by performing binarization processing on an image. When the scribe line is detected in the previous stage in this way, the rotational angle error between the substrate having the scribe line and the image pickup means is taken full advantage of the pattern recognition method for the binarized enlarged captured image. Is calculated, and the θ stage on which the substrate is placed is driven so as to cancel the error.

[0007]

However, the scribe line detection method by the binarization processing using the mode method as described above has the following problems.

That is, in the binarization processing, in an image obtained by photographing the surface of the substrate, the area of the scribe line is a certain gradation value specific to the scribe line, and the area other than the scribe line (mainly a circuit pattern is formed). In the following description, it is assumed that the “pattern region” has a unique gradation value different from that of the scribe line and is in a state of a gradation value histogram showing bimodality as shown in FIG. .

However, the state of the surface of the substrate in each step of the semiconductor manufacturing has various aspects,
Not all substrates meet this premise, and it is often difficult to detect scribe lines with the method.

For example, when only a certain kind of film is formed in the pattern area and the intensity of the reflected light is almost the same between the pattern area and the scribe line area, the gradation value histogram is shown in FIG. It shows unimodality as shown in a). Further, at a certain stage of semiconductor manufacturing, various films are formed at various locations in the pattern region, and the gradation value histogram shows three or more peaks as shown in FIG.

Therefore, according to the conventional method, it is difficult to set a threshold value, and since the binarization process itself cannot be performed, it is difficult to detect a scribe line, and it is often impossible to correct the rotation of the substrate. There is.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and a substrate rotation correction capable of accurately detecting a scribe line for various substrates and accurately correcting the rotation of the substrate. It is intended to provide a way.

[0013]

The present invention has the following configuration in order to achieve the above object. That is, the present invention provides a method of correcting the rotation of the imaging optical unit and the substrate so that the image of the scribe line of the substrate obtained by the enlarged imaging is parallel to a predetermined direction. An integration process of performing an integration process of a grayscale value for each pixel row parallel to the predetermined direction in the image with respect to the multi-gradation data obtained by imaging the intersection area of the scribe line; A differential processing step of differentiating the obtained integrated data arranged in a direction perpendicular to the predetermined direction, and a peak value detecting step of detecting a peak value of the differential data obtained in the differential processing step,
A rotation correction step of relatively rotating and shifting the imaging optical unit and the substrate in a direction in which the vertical fluctuation width of the differential data is maximized.

The method of relatively rotating and shifting the imaging optical means and the substrate in a direction in which the vertical fluctuation width of the differential data is maximum is not particularly limited. The vertical fluctuation width of each differential data at at least three rotational displacement positions obtained by rotational displacement is detected, and the vertical fluctuation width of the differential value at these three positions is converted into an approximate polynomial, that is, the rotational displacement is used as a variable. By applying a predetermined approximation polynomial as an approximation to the function of the vertical fluctuation width of the differential data, calculating the angular position at which the vertical fluctuation width of the differential value shows the maximum value, and rotating the displacement amount of the angular position from the reference position Error method,

The substrate and the imaging camera system are rotationally displaced in order by a relatively small angle, and the vertical fluctuation width of the differential data at each rotational displacement position is sequentially compared to determine an angular position where the vertical fluctuation width is maximum, There is a method of using a displacement amount of the angular position from a reference position as a rotation error.

[0016]

The operation of the present invention is as follows. In the pattern region on the substrate surface, various films are formed so as to constitute a semiconductor circuit, and the pattern region has one or more films than the scribe lines. Because of the step due to the difference,
It is inclined on the substrate surface.

By the way, in an image obtained by photographing a substrate with an incident-light microscopic optical system, the light illuminating the substrate is limited to light emitted from the objective lens. Is reflected outside the entrance pupil of the epi-illumination microscopic optical system due to the slanted edge, and the gradation (brightness, light intensity) value sharply changes at the edge of the scribe line in this image. .

Therefore, in the integration process of the present invention, when the multi-gradation image data including the scribe line is obtained for each pixel row in the reference axis direction of the image pickup camera system in order, the integration of the gradation value is performed. The integrated data changes in the pixel row region passing through the edge.

In the differentiation process, the degree of change of the integrated data of each pixel row, that is, the differential data obtained by differentiating the integrated data is obtained, and the peak value of the differential data is obtained in the peak value detecting process. The peak value of the differential data changes according to the amount of rotational deviation between the scribe line on the substrate and the imaging optical unit. In other words, the smaller the amount of rotational displacement between the substrate and the imaging optical means, the greater the degree of change in the integral data, so that the peak value of the differential data increases (it decreases with a negative peak value). As described above, since there is a correlation between the rotation error of the substrate and the vertical fluctuation width of the differential data obtained by differentiating the integrated data of the gradation value of each pixel column, in the rotation error detection process, Based on the vertical fluctuation width of the differential data obtained at each of the rotation angle positions at a plurality of positions on the substrate, the amount of rotation deviation between the substrate and the imaging optical means is detected. The rotation error of the substrate is substantially corrected by relatively rotating and displacing the substrate and the imaging optical unit.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings. First Embodiment FIG. 1 is a block diagram showing a schematic configuration of a film thickness measuring apparatus used in this embodiment. Here, a film thickness measuring apparatus is given as an example of an apparatus to which the method of the present invention is applied,
The method of the present invention can also be applied to, for example, various types of characteristic measuring devices provided with a positioning mechanism using scribe line detection.

In FIG. 1, reference numeral W denotes a substrate such as a semiconductor wafer having scribe lines formed on the surface. The substrate W moves horizontally in two orthogonal directions (X and Y directions).
It is mounted on a θ stage 1b that rotates with the Y stage 1a. Reference numeral 2 denotes an objective lens arranged to face the substrate W, and the illumination light emitted from the light source 3 falls on the substrate W via the half mirror 4 and the objective lens 2. The light reflected from the substrate W is incident on the half mirror 5 via the objective lens 2 and the half mirror 4, and a part of the light is reflected and incident on the television camera 6, and the surface of the substrate W is magnified and imaged. A series of optical means including the light source 3, the half mirror 4, the objective lens 2, and the half mirror 5 constitute an incident light microscopic optical system. The optical system required to carry out the method according to the present invention is not limited to the structure shown in FIG. 1, but may be any as long as it constitutes an incident-light microscope optical system.

A multi-tone image on the surface of the substrate W is converted into a CRT image through an image processing unit 7 for performing a positioning process described later.
8, an enlarged image of the surface of the substrate W is displayed. The image processing unit 7 detects a rotation error between the scribe line of the substrate W and the X-axis or the Y-axis which is the reference axis of the imaging camera system by a rotation correction process described later in detail, and outputs the result via the XYθ stage drive circuit 9. And θ stage 1b
To correct the rotation of the substrate. When the rotation error of the substrate is corrected, the image processing unit 7
The XY stage 1a is moved via the XYθ stage drive circuit 9 by the movement error between the scribe line and the reference axes X and Y axes of the imaging camera system, and the position correction of the substrate W is completed.

After the alignment, the reflected light from the film thickness measuring spot on the substrate W is incident on the spectroscope 10 via the objective lens 2 and the half mirrors 4 and 5, and the film thickness is measured. Will be

Hereinafter, referring to the flowchart of FIG.
A description will be given of the substrate rotation correction processing operation in the present embodiment. It should be noted that since the correction processing of the movement error performed after the rotation correction processing is not the gist of the present invention, the description thereof is omitted.

Steps S1 and S2: Image processing unit 7
After resetting the counter for counting the number of times of image capturing, the enlarged multi-tone image of the scribe line area of the substrate W captured by the television camera 6 is captured into the image processing unit 7. Since the image captured by the image processing unit 7 is an image captured through the incident-light microscopic optical system as described above, the tone value changes at the edge of the scribe line on the substrate W.

This is because of a step due to a height difference between the scribe line area and the pattern area on the substrate surface.
This is because at the edge of the scribe line, the illumination light emitted from the objective lens 2 is reflected outside the entrance pupil of the objective lens 2 and does not go to the television camera 6.

When the substrate surface is observed with a magnifying glass or when the substrate surface is photographed with natural light, the substrate is illuminated with light from a wide range of directions, so that the edges of the scribe lines are dark (small gradations). (By value) I never said I could see or be photographed. In the present invention, the reason why the gradation value changes at the edge of the scribe line as described above is that in the present invention, the substrate surface is photographed by the incident-light microscopic optical system.

FIG. 3A shows a state where the substrate W is taken into the image processing unit 7 and projected on the CRT 8 when the substrate W is at the initial position (here, the initial position is set to 0 °).
3 shows a multi-tone image of the surface of FIG. As shown in the figure,
The substrate W that has not yet been subjected to the rotation correction is a relative to a reference axis of the imaging camera system (here, the Y axis is used as a reference).
There is a rotation error of °.

Step S3: With respect to the multi-tone image taken into the image processing unit 7, the image data of each pixel row in the Y direction, which is the reference axis of the imaging camera system, is integrated. Specifically, as shown in FIG. 3A, assuming that the upper left end of the figure is the origin (0, 0), each pixel L _x0 , L _x1, .., _Lx255 as a starting point, the gradation value is integrated (integrated) for each of the 256 pixel rows extending in the range from Y = 0 to Y = 239 and parallel to the Y direction. FIG. 3B is a distribution diagram of the Y-direction grayscale integrated values obtained in this manner. In the figure, the vertical axis indicates the integrated value obtained by replacing the maximum integrated value with “1.0”.

As described above, the epi-illumination causes the substrate W
3A, the gradation value changes at the edge of the scribe line area (hatched area) shown in FIG. 3A, so that the edge of the scribe line in the Y direction is changed as shown in FIG. The integral data of the pixel row region E that crosses is changing.

Step S4: 25 obtained in step S3
Differentiate the six integral data. FIG. 3C is a distribution diagram of the differential values obtained in this manner. In the differential value distribution diagram, four positive and negative peaks appear according to the degree of the slope of the integral data shown in FIG.

[0032] Step S5: Here, the vertical variation width of the differential value obtained in step S4, i.e. the sum D ₀ of the absolute value of the absolute value and the minimum peak value of the maximum peak value. The vertical fluctuation width D ₀ increases as the rotation error of the scribe line of the substrate W with respect to the reference axis of the imaging camera system decreases.

Steps S6 to S8: Steps S1 to S5
When the vertical fluctuation width D ₀ is detected for the substrate W at the initial position by the processing of the above, the counter in the image processing unit 7 is counted up by “1”, and if the counted value of the counter is “1”, the substrate W Stage 1 on which is mounted
b is rotated, for example, clockwise by a predetermined angle α.

Then, returning to step S2, the image data at that position is fetched in the same manner as described above, and then the integration processing (step S3) and the differentiation processing (step S4) in the reference direction are performed. Request width D ₁ (step S5). FIG. 4A shows the image processing unit 7 at this time.
FIG. 4B shows a multi-tone image of the substrate W captured in FIG.
FIG. 4C is a distribution diagram of the integral value of each pixel row along the reference axis Y of the imaging camera system, and FIG. 4C is a distribution diagram of the differential value of FIG. In the illustrated example, the rotational displacement of the angle α
Since the inclination between the scribe line in the Y direction and the reference axis Y of the imaging camera system is larger than the initial position in FIG. 3, the inclination of the integrated value in FIG.
Therefore, the smaller the value of the vertical variation width D ₁ shown in FIG. 4 (c).

[0035] Step S9, S10: When detecting the vertical variation width D _1, wherein the counter is further incremented,
Since the count value n becomes "2", the process proceeds from step S9 to step S10. In this step S10, the substrate W is rotationally displaced counterclockwise by 2α ° from that position.

[0036] Then, the same process as in step S2~S5 described above, to detect the vertical variation width D ₂ at that location. FIG. 5A shows the image processing unit 7 at this time.
FIG. 5B shows a multi-tone image of the substrate W captured in FIG.
FIG. 5C is a distribution diagram of the integral value of each pixel row along the reference axis Y of the imaging camera system, and FIG. 5C is a distribution diagram of the differential value of FIG. In the illustrated example, the inclination between the scribe line in the Y direction and the reference axis Y of the imaging camera system is halfway between the initial position in FIG. 3 and the rotational displacement position in FIG. 4 due to the rotational displacement of the angle −2α. Therefore, the vertical fluctuation width D ₂ shown in FIG.
Is a value belonging to the middle between the vertical fluctuation widths D ₀ and D ₁ .

Steps S11 and S12: As described above,
Initial position of substrate W, rotational displacement position at angle α °, and angle
Vertical fluctuation width D at a rotational displacement position of -2α °₀, D₁,
D_Two Is detected, the vertical fluctuation at the initial position
Width D₀Vertical fluctuation width at the rotational displacement position with respect to
D₁, D_TwoJudge the magnitude relationship of Vertical fluctuation range D₀But,
Vertical fluctuation range D₁, D_TwoLarger than (see FIG. 3 described above).
To the case of FIG. 5), the vertical fluctuation width D₀, D₁, D_TwoIs a figure
The relationship is as shown in Fig. 6, which is approximated by the dashed line in the figure.
Can be represented as a point on a quadratic curve, and will be described later.
As described above, the angular position a of the local maximum value is determined relatively accurately.
be able to.

On the other hand, D ₁ or D is larger than the vertical fluctuation width D _{0.
If the value of 2} is larger, the vertical fluctuation widths D ₀ , D ₁ , D ₂
However, since it is biased to the left or right side of the local maximum value in FIG. 6, the detection accuracy of the angular position of the local maximum value is deteriorated. Therefore,
In such a case, the process proceeds to step S13.

Step S13: Here, the rotational displacement angle α
Is set to a larger value (α + Δα). Then, the processing of steps S1 to S10 described above is repeatedly executed, and
The vertical fluctuation ranges D ₀ , D ₁ , and D ₂ that satisfy the conditions of steps S11 and S12 are detected.

Step S14: As described above, the vertical fluctuation widths D ₀ , D ₁ , and D ₂ are approximately ₂ as shown in FIG.
It can be represented as a point on the following curve. This quadratic curve indicates the change in the vertical fluctuation width related to the rotation error of the substrate W with respect to the reference axis of the imaging camera system, that is, the degree of change in the integrated data of each pixel column. When the reference axis of the imaging camera system and the direction of the scribe line of the substrate W match, the degree of change of the integrated data of each pixel column, that is,
Since the upper and lower variation range of the differential data is largest, by obtaining the rotational angular position a of the quadratic curve conversely takes a maximum value D _MAX, calculates the rotation angle error of the substrate W with respect to the reference axis of the imaging camera system can do.

Therefore, in this step S14, the vertical fluctuation ranges D ₀ , D ₁ , D
_2, by substituting the approximate polynomial shown below, obtaining the rotational angular position a to take the maximum value D _MAX.

The approximate polynomial for obtaining a maximum value D _MAX is represented by the following formula (1). y = AX ² + BX + C (1) In the above equation (1), y is a peak value, X is a rotational angle position, and A, B, and C are unknown coefficients (A <0).

The rotation angle position a having the local maximum value D _MAX is a value at which the first derivative of the above equation (1) becomes “0”, and is obtained by the following equation (2). a = −B / 2A (2)

To determine the unknown coefficients A, B, C,
Substituting the vertical fluctuation ranges D ₀ , D ₁ , and D ₂ into the equation (1) yields the following. D ₀ = C (3) D ₁ = Aα ² −Bα + C (4) D ₂ = Aα ² + Bα + C (5)

By solving the above equations (3) to (5), the coefficients A and B can be expressed as follows. A = (D ₁ + D ₂ −2D ₀ ) / 2α ² (6) B = (D ₁ -D ₂ ) / 2α (7)

By substituting the above equations (6) and (7) into the equation (2), the rotation angle position a having the maximum value D _MAX is given by the following equation (8)
It is represented as a = {(D ₂ −D ₁ ) / (D ₁ + D ₂ −2D)} × α / 2 (8)

That is, the detected vertical fluctuation widths D ₀ , D
By applying ₁ , D ₂ and the predetermined rotational displacement angle α to the above equation (8), the rotational angle position a having the maximum value D _MAX can be obtained.

Step S15: The substrate W is placed in step SS11.
And in S12 in D ₀ -D _1> 0 and D ₀ -D _2> position where the vertical variation width D ₀ that satisfies obtained any of 0, the reference axis of the imaging camera system, determined in Step S14 Because it has been rotationally displaced by the given angle a °,
On the basis of the position where D ₀ is obtained, θ stage 1b
Is rotated so as to be positioned at an angle of -a °, and the scribe line of the substrate W is made to coincide with the reference axis of the imaging camera system, thereby performing the rotation correction of the substrate W.

In the above-described embodiment, the change in the vertical fluctuation range of the integral data is approximated by a quadratic polynomial. However, a stricter approximate polynomial is used, and a rotation angle position at which the approximate polynomial takes a maximum value is obtained. Rotation correction may be performed.

Second Embodiment In the first embodiment, the vertical fluctuation width at three different rotation angle positions is applied to a predetermined approximation polynomial,
The rotation error of the substrate W is detected, but in the second embodiment, the substrate and the imaging camera system are sequentially rotated and displaced by a small angle, and the vertical fluctuation width of the differential data at each rotational displacement position is sequentially determined. By comparison, an angular position at which the vertical fluctuation width becomes maximum is obtained, and a displacement amount of the angular position from a reference position is detected as a rotation error.

Hereinafter, description will be made with reference to the flowcharts shown in FIGS. Step N1: In order to efficiently detect the rotation error of the substrate W, it is determined in which direction the substrate W should be rotationally displaced. Specifically, the processing shown in FIG. 8 is performed.

That is, the counter in the image processing unit 7 is reset (step N1 ₁ ), and the image data at the initial position is fetched (step N1 ₂ ). Then, as described in the first embodiment, the image data of each pixel row in the reference axis direction of the imaging camera system is integrated (step N1 ₃ ), and the integrated data is differentiated (step N1 ₄ ). detecting the vertical variation width D ₀ of (step N1 _6).

Next, the counter counts up by "1" (Step N1 _7), if the count n of the counter is "1", the θ stage 1b, for example, rotates in the clockwise direction by a very small angle Δθ (step N1 _9). Then, the process returns to step N1 _2, captures image data at that position, to detect the vertical variation width D ₁ in the same manner as described above.

[0054] As described above, the vertical variation width D ₀ at the initial position, the the vertical variation width D ₁ of the at position rotated displaced by Δθ clockwise is obtained, the vertical variation width D _0, D ₁ magnitude The relations are compared (step N1 ₁₀ ). As shown in FIG. 9a, when towards the vertical variation width D ₁ is greater than D _0, by displacing the substrate W in a clockwise direction, to match the faster the reference axis and the scribe line of the imaging camera system In this case, the rotation direction setting flag F is set to "1" (step N1 ₁₁ ). On the other hand, FIG.
As shown in the figure, if the vertical fluctuation width D ₀ is larger than D ₁ , it is more efficient to displace in the direction opposite to the rotational displacement direction in step N ₁₉ , so the flag F is set to “0”. (Step N1 ₁₂ ).

When the rotation direction is determined as described above, the θ stage 1b is returned to the initial position (step N).
1 ₁₃ ), and proceed to the next step N2. Step N2-N
4: It is determined whether or not the flag F is "1".
= 1, the θ stage 1b is rotated clockwise by a small angle Δ
Rotationally displaces by θ. If the flag F = 0, the θ stage 1b is rotationally displaced counterclockwise by a small angle Δθ.

Steps N5 to N8: The image data of the substrate W is fetched at the position where it has been slightly displaced, and the image data of each pixel array along the reference axis of the imaging camera system is integrated in the same manner as described above. the integrated data differentiated processing to detect the vertical variation width D _n of the obtained differential values.

Step N9: Capture of current image data
Vertical fluctuation width D obtained by_n And the previous rotational displacement
Vertical fluctuation range D_n-1Compare with The up and down movement this time
Width D_nIs the previous vertical fluctuation width D_n-1If greater than
Is the previous vertical fluctuation width D_n-1Is not the maximum value mentioned above.
Therefore, returning to step N2, the θ stage 1b is further moved
It is slightly displaced by Δθ (or −Δθ). Soshi
The image data of the substrate W at that position
The vertical fluctuation width is detected, and the determination in step N9 is performed.
In the judgment of step N9, D_n-1-D_nUntil> 0 holds
Then, the processing of steps N2 to N9 is repeatedly performed.

Step N10: As shown in FIG. 10, D _n-1
If the relationship of -D _n > 0 is established, the vertical fluctuation width D _n-1 is determined to be the maximum value, and the θ stage 1b is set to the position θ _n-1 returned by Δθ to the original position, whereby the substrate The rotation correction of W ends.

In the second embodiment, in order to efficiently detect the rotation error, the processing for setting the rotation direction is provided in the first step N1, but the substrate W is slightly rotated and displaced in a fixed direction. By doing so, the rotational angle position where the vertical fluctuation width of the differential data takes a local maximum value may be detected.

In each of the above embodiments, the sum of the absolute value of the maximum peak value and the absolute value of the minimum peak value of the differential data is calculated as
Although the vertical fluctuation width of the differential data is used, the maximum peak value may be used as the vertical fluctuation width, or the absolute value of the minimum peak value may be used as the vertical fluctuation width.

[0061]

As is apparent from the above description, according to the present invention, the substrate on which the scribe lines are formed is photographed by the epi-illumination microscopic optical system, and the multi-gradation image data is taken by the imaging camera system. Integral processing is sequentially performed on each image sequence along the reference axis, the obtained integral data is differentiated, and each processing of detecting the vertical fluctuation width of the differentiated data is executed at a plurality of rotation angle positions, respectively. In the direction in which the vertical fluctuation width of the differential data is maximized, based on the relative rotational displacement of the imaging optical unit and the substrate, the rotation of the substrate is substantially corrected, so the conventional mode method is used. 2
Since it is difficult to binarize the image of the substrate as in the method based on the binarization process, it is difficult to detect the scribe line itself, so that the rotation correction of the substrate is not disabled, and the surface state is various. The rotation can be accurately corrected for a simple substrate.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a film thickness measuring device commonly used in each embodiment of the present invention.

FIG. 2 is an operation flowchart of the first embodiment.

FIG. 3 is a distribution diagram of a captured image of a substrate at a first rotational displacement position, an integrated value of the captured image data, and a differential value obtained by differentiating the integrated data in the first embodiment.

FIG. 4 is a distribution diagram of a captured image of a substrate at a second rotational displacement position, an integrated value of the captured image data, and a differential value obtained by differentiating the integrated data in the first embodiment.

FIG. 5 is a distribution diagram of a captured image of a substrate at a third rotational displacement position, an integrated value of the captured image data, and a differential value obtained by differentiating the integrated data in the first embodiment.

FIG. 6 is an explanatory diagram of a rotation error detection process using the detected vertical fluctuation width in the first embodiment.

FIG. 7 is an operation flowchart of the second embodiment.

FIG. 8 is a detailed flowchart of a rotation direction setting process according to the second embodiment.

FIG. 9 is an explanatory diagram of a rotation direction setting process according to the second embodiment.

FIG. 10 is an explanatory diagram of a rotation error detection process using the detected vertical fluctuation width in the second embodiment.

FIG. 11 is a diagram showing a state in which an intersection area of a scribe line on a substrate is enlarged and imaged according to a description of a conventional example.

12 is a diagram illustrating an example of a tone value histogram of the image of FIG. 11;

FIG. 13 is a diagram showing a tone value histogram for explaining a problem of the conventional example.

[Explanation of symbols]

 W ... Substrate 1a ... XY stage 1b ... Theta stage 2 ... Objective lens 3 ... Light source 4,5 ... Half mirror 6 ... TV camera 7 ... Image processing unit 8 ... CRT 9 ... XYθ stage drive circuit 10 ... Spectroscope

Continuation of the front page (56) References JP-A-57-100742 (JP, A) JP-A-60-49642 (JP, A) JP-A-62-150112 (JP, A) JP-A-62-279654 (JP) JP-A-64-59829 (JP, A) JP-A-54-29977 (JP, A) JP-A-62-181429 (JP, A)

Claims (1)

(57) [Claims] 1. A method for correcting the rotation of an imaging optical unit and a substrate so that an image of a scribe line of a substrate obtained by enlarging and imaging is parallel to a predetermined direction, wherein the imaging optical unit is an incident-light microscope. An integration process of performing an integration process of a gradation value on multi-grayscale data obtained by imaging an intersection region of a scribe line with respect to each pixel row parallel to the predetermined direction in the image; Differentiation processing step of differentiating the integrated data arranged in the direction perpendicular to the predetermined direction, and a peak value detection step of detecting a peak value of the differential data obtained in the differentiation processing step,
A rotation correction step of relatively rotating and shifting the imaging optical unit and the substrate in a direction in which the vertical fluctuation width of the differential data is maximized.