JPH05313380A - Aligning device - Google Patents

Abstract

PURPOSE:To obtain the central position of a mark for alignment on a substrate which is not read because it is hidden behind a mask and to perform the alignment of the mask with the substrate. CONSTITUTION:The marks for alignment 10a-10d and 11a-11d on the mask 10 and the substrate 11 are read by CCD cameras 13a-13d, and processed by an image processor 15 and a computer 17 to obtain the central positions of the respective marks for alignment. In the case that the mark 11c is not read because it is hidden behind the mask 10, the intersection of a circle with center at the central position 11b and with the radius of r2 which is center-to-center distance between the marks for alignment 11b and 11C with a circle with center at the central position 11d and with the radius of r1 which is center-to-center distance between the marks for alignment 11d and 11c is obtained to be set as the central position of the mark for alignment 11c. Then, a moving table 12 is driven to be aligned through a control board 19 so that the central positions of the respective marks for alignment on the mask 10 may be respectively aligned with the central positions of the respective marks for alignment on the substrate 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alignment device for performing relative alignment between objects to be processed using image recognition technology.

[0002]

2. Description of the Related Art Conventionally, in an exposure apparatus or a printing apparatus used for manufacturing a printed wiring board or a semiconductor substrate, two objects to be processed, such as an exposure mask, which are superposed or opposed to each other, for example, during edging. Image recognition technology is used for accurate alignment between a screen mask (hereinafter collectively referred to as "mask") and a semiconductor substrate or printed circuit board (hereinafter collectively referred to as "substrate"). ..

That is, in such an apparatus, the mask and the substrate are aligned, for example, as follows.

Four alignment marks are provided on each of the mask and the substrate. The mask alignment mark is formed by an opening. Then, the mask alignment mark and the substrate alignment mark are read from the mask side. The alignment mark on the substrate is read through the alignment mark on the mask, which is an opening. And
The positions of the centers of gravity of the read alignment marks of the mask and the substrate are obtained, and the mask and the substrate are aligned so that they coincide with each other.

As a conventional technique using such an image recognition technique, there are known techniques described in Japanese Patent Application Laid-Open No. 61-229386 and Japanese Utility Model Laid-Open No. 62-69243.

[0006]

By the way, in the alignment using the above-mentioned image recognition means, when the entire contents of the alignment marks on the substrate can be read through the alignment marks on the corresponding mask, The position of the center of gravity of the substrate can be accurately obtained. However, it is not possible to accurately determine the position of the center of gravity of the alignment mark on the substrate that is partially hidden by the mask and cannot be read. Further, the position of the center of gravity cannot be obtained for the alignment mark on the substrate that is completely hidden by the mask and cannot be read. Therefore, even if only one alignment mark on the substrate is completely hidden by the mask, alignment cannot be performed.

Therefore, according to the present invention, even if the alignment marks on one or two substrates are completely hidden by the alignment marks on the mask and cannot be read at all, the alignment device can perform alignment. The purpose is to provide.

[0008]

[Means for Solving the Problems] To achieve the above object,
The present invention relates to a positional relationship between a first object to be processed having light transmitting holes arranged at four positions with a predetermined positional relationship and the respective light transmitting holes arranged in parallel with the first object to be processed. A second processing object having positioning marks arranged at four positions having the same positional relationship as that of the first processing object. A camera for photographing from the opposite side of the second object to be processed, and a camera for photographing the second object to be processed through each of the light transmission holes of the first object to be processed, and the four positions where the images are taken. Image processing means for calculating the center position of the light transmission hole and the center position of the alignment mark for the second object to be processed photographed through the four light transmission holes, and the camera, Positioning of 2 or 3 of the second object to be processed through the four light transmitting holes. Means for determining the center position of the alignment mark that has not been photographed from the center position of each photographed alignment mark and the positional relationship between each of the alignment marks when only the bake marks have been photographed And the first object to be processed and the second object to be processed so that the center positions of the four light transmitting holes and the center positions of the four alignment marks of the second object match. And a means for relatively moving an object.

[0009]

According to the alignment apparatus of the present invention, only two or three alignment marks of the second object to be processed can be photographed by the camera through the four light transmission holes. If not, the center position of the alignment mark that has not been photographed is determined from the positional relationship between the photographed center positions of the alignment marks and the alignment marks, and At least one of the first processed object and the second processed object so that the center position of the light transmitting hole and the center position of the four alignment marks of the second processed object coincide with each other. To move. Therefore, even when the alignment marks on one or two substrates are completely hidden by the first object to be processed and cannot be read at all, the alignment can be performed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the alignment apparatus according to the present invention will be described below.

FIG. 1 shows the arrangement of the alignment apparatus according to this embodiment.

As shown in the figure, the alignment apparatus according to the present embodiment has a mask 10, a substrate 11 arranged to face the mask 10, and a substrate 11 mounted on each of X, Y, θ, and Z. A moving table 12 for moving the mask 10 and the substrate 11 to align the mask 10 and the substrate 11 with each other.
Positioning marks 10a to 10d and 1 provided in the corners
CCD cameras 13a to 13d for imaging 1a to 11d
And a camera controller 14 for inputting and controlling the video signals of the cameras 13a to 13d, and binarizing the picked-up images of the alignment marks 10a to 10d and 11a to 11d of the mask 10 and the substrate 11 to determine the position of the center of gravity. The image processing device 15 for calculation, the monitor 16 for displaying the images captured by the CCD cameras 13a to 13d and the image after binarization processing, and the movement amount calculation of the movement table 12 based on the gravity center position information from the image processing device 15. A computer 17 for controlling the operation of the moving table 12, an operation console 18 for giving a command to the computer 17, and a control panel 19 for moving the moving table 12 based on the command from the computer 17. Here, X and Y are coordinate axes on a plane parallel to the moving table plane, Z is a coordinate axis perpendicular to the moving table plane, and θ.
Denotes the angle of rotation about an axis perpendicular to the plane of the moving table.
In addition, the alignment marks 11a to 11d on the substrate 11
Are provided at four apexes of a rectangle set on the substrate 11, and the alignment marks 10a to 10d of the mask 10 are provided at four apexes of a rectangle congruent with the previous rectangle set on the mask 10.

Further, the position of each pixel on the image photographed by the CCD cameras 13a to 13d is a rectangular coordinate (Xi, Yi) set on a plane parallel to the moving table plane.
The calculation of the center of gravity of the alignment mark and the distance between the alignment marks is performed using the X coordinate value and the Y coordinate value of the pixel corresponding to the object.

FIG. 2 shows the positional relationship among the CCD camera 13a during the alignment process, each alignment mark 10a on the mask, and the alignment mark 11a on the substrate 11. This relation is different from the others. CCD cameras 13b-1
The same applies to 3d.

Now, as shown in FIG. 2, in this embodiment,
The positioning mark 10a on the mask 10 is a circular opening, and a donut-shaped portion that does not transmit light is provided around the opening. The portion around the circular aperture that does not transmit light may be square. However, regardless of whether it is circular or rectangular, the size of the portion that does not transmit light except the aperture is CCD.
It is made sufficiently larger than the visual field of the camera 13a. On the other hand, substrate 1
The first alignment mark 11a is an aperture (for example, a through hole) provided in the substrate, and the aperture diameter is smaller than the aperture diameter of the alignment mark 10a of the mask 10.

In the alignment process, light is applied to the mask 10 from above the moving table 12 (reflection illumination), and the reflected light 21 from the alignment mark 10a is captured by the CCD camera 13a to form an image. In addition, the moving table 12
Light is applied from the inside toward the lower surface of the substrate 11 (transmissive illumination), and the transmitted light 22 of the alignment mark 11a is CC-illuminated through the opening of the alignment mark 10a of the mask 10.
The image is captured by the D camera 13a. In this way, a difference in brightness occurs between the reflected light 21 and the transmitted light 22 captured by the CCD camera 13a. Therefore, by utilizing this, the image processing device 15 clarifies and recognizes the contours of both alignment marks 10a and 11a while removing noise by the binarization process. Note that the method of detecting both alignment marks may be another method.

Now, each of the alignment marks 10a-10
When the images of the apertures d, 11a to 11d are image-processed by the image processing device 15, the alignment marks 10a to 10a.
Positioning marks 11a to
In the case where a small circle, which is an image of 11d, is formed and the entire contents of both alignment marks can be read, the computer 1
7 each alignment mark 10a-10d, 11a-1
The barycentric position of 1d can be easily calculated. The positions of their centers of gravity are the alignment marks 10a to 10d and 11a to 11d.
Since it coincides with the center position of the mask 10, the control table 19 drives the moving table 12 so that the center of gravity of the alignment mark of the substrate 11 is aligned with the center of gravity of the fixed mask 10. Can be aligned.

However, if any of the small circles, which are the images of the alignment marks 11a to 11d of the substrate, is not included in the large circles, which are the images of the alignment marks 10a to 10d of the mask 10, the image cannot be read. The position of the center of gravity cannot be obtained for the identification positioning mark. Therefore, in the present embodiment, the central position of such an unreadable substrate alignment mark is calculated by the computer 17.

First, as shown in FIG. 3, a case where one alignment mark 11c of the substrate 11 is completely out of the great circular opening of the alignment mark 10c of the mask 10 and cannot be read will be described as an example. ..

In this case, first, the read mask 10 is read.
Center positions 30 of the alignment marks 10a to 10d and the alignment marks 11a, 11b, 11d of the substrate 11
a to 30d and 31a, 31b and 31d are obtained from the respective barycentric positions. Next, since the center-to-center distance r2 between the alignment marks 11b and 11c and the center-to-center distance r1 between the alignment marks 11d and 11c are known, a radius r2 with the center position 11b as the center. Circle of 11
An intersection 31c of a circle centered on d and having a radius r1 is obtained. Then, the intersection 31c is set as the center position of the alignment mark 11c. Now, the alignment mark 11 on the substrate
Since the center position 31c of c has been obtained, the center positions 30a to 30 of the alignment marks of the mask 10 are similar to the above.
d and the center position 31a of the alignment mark of the substrate 11
The movable table 12 is driven through the control panel 19 so that 31d are matched with each other, and alignment is performed.

Next, as shown in FIG. 4, when the two alignment marks 11c and 11d of the substrate 11 are completely out of the great circular holes of the alignment marks 10c and 10d of the mask 10 and cannot be read. Will be described.

In this case, first, the read mask 10 is read.
Centering positions 30a to 30 of the positioning marks 10a to 10d and the positioning marks 11a and 11b of the substrate 11.
Find d and 31a, 31b. And the central position 31a
And 31b on the straight line connecting the centers of the center positions 31a, 31
Vertical lines 41a and 41b are erected from b in the direction in which the alignment marks 11c and 11d should exist. Since the center-to-center distance r2 between the alignment marks 11a and 11d or between 11b and 11c is known, the perpendicular line 41a from the center positions 31a and 31b,
41b and a radius r centered on the center positions 31a and 31b
The intersection points 31d and 31c of the circle of 2 are obtained, and the intersection points 31c and 31c
31d is the center position of the alignment marks 11c and 11d. Now, the substrate alignment marks 11c, 1
Since the center positions 31c and 31d of 1d are obtained, the center position 3 of the alignment mark of the mask 10 is the same as the above.
The moving table 12 is driven through the control board 19 so that the center positions 0a to 30d and the center positions 31a to 31d of the positioning marks on the substrate 11 are aligned with each other, and the positioning is performed.

In the above embodiments, the application to the apparatus for aligning the substrate and the mask has been described, but this embodiment is also applicable to other apparatuses for aligning the object to be processed. Can be applied.

[0024]

As described above, according to the present embodiment, even if the alignment marks on one or two substrates are completely hidden by the alignment marks on the mask and cannot be read at all, the position It is possible to provide an alignment device that can perform alignment.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an alignment apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing how an alignment mark is imaged.

FIG. 3 is an explanatory diagram showing a first method for determining the center position of an unaligned alignment mark.

FIG. 4 is an explanatory diagram showing a second technique for determining the center position of the alignment mark that cannot be read.

[Explanation of symbols]

 10 ... Mask 10a-10d ... Mask alignment mark 11a-11d ... Substrate alignment mark 12 ... Moving table 13a-13d ... CCD camera 14 ... Camera controller 15 ... Image processing device 16 ... Monitor device 17 ... Computer 18 ... Operation console 19 ... Control panel 30a to 30d ... Center of mark for alignment of mask 31a to 31d ... Center of mark for alignment of substrate 41a, 41b ... Perpendicular

Claims (1)

[Claims] 1. A first object to be processed having light transmitting holes arranged at four positions with a predetermined positional relationship, and a position between the respective light transmitting holes arranged in parallel with the first object to be processed. A positioning device for performing positioning between a second processed object having positioning marks arranged at four positions having the same positional relationship as the relationship, wherein the first processed object is A camera for photographing from the opposite side of the second object to be processed and photographing the second object to be processed through each of the light transmission holes of the first object to be processed; Image processing means for calculating the center position of the light transmission holes at the points and the center position of the alignment mark for the second object to be processed photographed through the four light transmission holes;
By the camera, through the four light transmission holes,
When only two or three alignment marks of the second object are photographed, the center position of the alignment mark that is not photographed is defined as the center position of each photographed alignment mark. Means for determining the positional relationship between the respective alignment marks, and the center positions of the four light transmission holes and the center positions of the four alignment marks of the second object to be processed coincide with each other. , The first object to be processed and the second object
And a means for moving the object to be processed relative to each other.