JPH0620920A - Substrate-position compensator - Google Patents

Abstract

PURPOSE:To detect positional displacement at the time of conveyance of a reticle etc., and to compensate positional displacement safely and positively before a stage is delivered. CONSTITUTION:The corners of a rectangular substrate 1 held on a substrate carrying member are image-sensed at specified positions by CCD cameras 2a, 2b. Signals from the CCD cameras 2a, 2b are image-processed by a substrate holding-position detecting means, and the position of the holding of the substrate 1 on the substrate carrying member is detected. The quantity of the positional displacement of the position of the holding of the substrate 1 detected by the substrate holding-position detecting means and the proper holding position of the substrate 1 determined on the carrying member is computed by a positional- displacement quantity computing means. A positioning stage is moved by movement equal to the quantity of positional displacement from an initial position before the substrate 1 is delivered to the positioning stage by a stage control means, and the substrate 1 is delivered to the positioning stage at the position, and the positioning stage is returned to the initial position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate position correcting apparatus, and more particularly to detecting a positional deviation of a substrate such as a reticle or a wafer used in semiconductor manufacturing, and correcting the positional deviation before it is transferred to a positioning stage. And a substrate position correction device.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor manufacturing apparatus such as an exposure apparatus, in order to perform pre-alignment of a reticle, the end surface of the reticle conveyed to a predetermined position on a conveyance path is pressed against a fixed reference member by a movable member for positioning. The pre-alignment mechanism is widely used.

FIG. 6 shows an outline of this type of pre-alignment mechanism. In the figure, reference numeral 6 indicates a reference member 6 fixed at a predetermined position on the positioning stage. The reference member 6 is in the form of a rotatable cylindrical roller, and when the reticle 1 is conveyed to the vicinity of the reference member 6, the plurality of pressing members 7 retracted outside the conveyance path move in the arrow direction, By moving the reticle 1 along the holding surface and pressing the end surface of the reticle 1 against the reference member 6, the reticle 1 is positioned at an appropriate position. Alternatively, the pre-alignment mechanism of FIG. 6 is provided in the middle of the reticle transport path to position the reticle and then transport it to the positioning stage.

[0004]

However, in the above-mentioned conventional technique, when positioning the reticle 1,
The reticle 1 slides on the stage, and the reference member 6
Since the pressing member 7 contacts the end surface of the reticle 1,
There are problems that the holding surface of the reticle 1 is damaged, and that minute dust or the like is generated due to sliding or contact.

There is also a problem in that the positions of the reference member and the like must be set for reticles of various sizes.

Therefore, an object of the present invention is to solve the problems of the above-mentioned conventional techniques, and minimize the degree of contact with the position adjusting member and movement of the reticle itself such as sliding during handling of the reticle. It is an object of the present invention to provide a substrate position correction device capable of efficiently positioning a reticle.

[0007]

In order to achieve the above object, the present invention provides an image pickup means for picking up an image of a corner of a rectangular substrate held on a substrate conveying member at a predetermined position, and a signal from the image pickup means. Substrate holding position detecting means for performing image processing on the substrate conveying member to detect the holding position of the substrate on the substrate conveying member, and the substrate holding position detected by the substrate holding position detecting means and the substrate defined on the conveying member. Position shift amount calculating means for calculating the amount of position shift from the proper holding position of, and before the substrate is transferred to the positioning stage,
Stage control means for moving the positioning stage from an initial position by a movement amount equal to the positional deviation amount, and after returning the positioning stage to the initial position after the substrate is transferred to the positioning stage at this position, It is characterized by having.

[0008]

According to the present invention, the corner of the rectangular substrate held on the substrate carrying member is imaged by the image pickup means at a predetermined position, and the signal from the image pickup means is image-processed by the substrate holding position detection means. The holding position of the substrate on the substrate carrying member is detected, and the positional deviation amount between the holding position of the substrate detected by the substrate holding position detecting means and the proper holding position of the substrate defined on the carrying member is determined. Calculated by the shift amount calculation means, and before the substrate is transferred to the positioning stage by the stage control means, the positioning stage is moved from the initial position by a movement amount equal to the position shift amount,
Since the positioning stage is returned to the initial position after the substrate is transferred to the positioning stage at this position, the substrate such as a reticle does not have to be brought into contact with a position adjusting member or the like to be moved and adjusted. Predetermined positioning can be performed without damaging the holding surface of the device due to scratches or damage to the end surface due to contact.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the substrate position correcting device according to the present invention will be described below with reference to FIG. FIG. 1 is a schematic configuration diagram showing a schematic configuration of a reticle transport unit of the substrate position correction apparatus and a positioning stage S. In FIG. 2, the reticle 1 in the process of being transported to the positioning stage S by the transport arm 5 and the reticle 1'pre-aligned in the positioning stage S are shown in FIG.
It is schematically shown in some places.

In addition, two CCD cameras 2a and 2b, which are image pickup means, are orthogonal to the reticle 1 conveyance direction at predetermined intervals in the conveyance path with the lens surfaces La and Lb facing upward. It is lined up in the direction. These CCD cameras 2a and 2b are installed so as to image the corners of the front end of the conveyed reticle 1 in the traveling direction, and the corners of the reticle 1 are placed at predetermined positions on the light receiving portion of the image pickup surface of each CCD camera. A position detection sensor LS is installed in the transportation path to stop the position detection sensor LS.

The reticle 1 imaged on the light receiving surface of the CCD image pickup device inside through the lens system of the CCD cameras 2a and 2b.
The image at each corner is converted into a predetermined charge signal and output to the image signal processing unit 10. This image signal processing unit 10
Performs predetermined signal processing, then performs predetermined correction as preprocessing, and then performs feature extraction of the outer contour line of the reticle of the image. At this time, since the vertices of the corners are usually notched in the reticle shape, the contour lines of two adjacent sides are extended to calculate the vertex coordinates of the virtual corner. These coordinates are obtained as coordinate values on a predetermined coordinate system set on the screen of an image output device (not shown).

Further, the image signal processing unit 10 includes an arithmetic unit 11
Is connected, and the deviation between the holding position of the reticle 1 held by the transport arm 5 and the reticle position at the proper position described above is calculated in the calculation unit 11. By this deviation calculation, the amount of positional deviation (X, Y, θ) between the reticle 1 held by the transfer arm 5 and the proper holding position with no positional deviation.
Is required. The calculation procedure will be described later.

Further, the positional deviation amount (X, Y, θ) of the reticle obtained by the calculation unit 11 is output to the control unit 12 of the positioning stage S. The control unit 12 outputs a predetermined drive command to drive units 13 and 14 such as a DC motor that drives the XY stage 3 and the θ stage 4 that form the positioning stage S.

Here, the operation of detecting the positional deviation of the reticle by the above-mentioned CCD cameras 2a and 2b will be described with reference to FIGS.
Will be described with reference to. FIG. 2A is images 20a and 20b showing the left and right corners of the front end portion in the transport direction of the reticle 1 that is transported without positional deviation. At this time, the vertices of the respective corners are projected at the center position of the screen, and the coordinates of the center position of the screen at this time are set to be the same as the coordinates of the reticle proper holding position. In the images 20a and 20b, the coordinates of the vertices of the corners when the reticle is in the proper holding position and the coordinates of the vertices of the left and right corners of the reticle 1 that is being conveyed completely match, so in this case, the reticle is conveyed. Each term of the positional deviation amount (X, Y, θ) of the reticle 1 is calculated as zero.

On the other hand, FIG. 2 (b) is an image obtained by picking up an image of the reticle 1 being carried by the carrying arm 5 in a state where there is a positional deviation. Two images 20a, 20b
When both are displayed side by side, the vertices of the corners of the reticle 1 are projected on both images at positions offset from the image center position. Note that in FIG. 6B, it can be seen that a predetermined amount of positional deviation has occurred with respect to the reticle (shown by a broken line) in the state where there is no positional deviation shown for explanation.

A method for quantitatively calculating this positional deviation amount will be described with reference to FIGS. 3 and 4. FIG. 3 is an explanatory diagram showing the positional relationship between the CCD cameras 2a and 2b and the reticle 1 carried in the imaging field of view. Here, the lens center position of the CCD camera 2a is B, and the lens center position of the CCD camera 2b is A. At this time, in this embodiment, the distance between the centers of the two lenses is set to be equal to the dimension in the width direction perpendicular to the transport direction of the reticle 1, and the CCD camera 2a,
The image 2b can be imaged at the same size as the reticle 1. The positions of the vertices of the corners of the reticle 1 imaged at this time are C and D as shown in FIG.

That is, the positional deviation between the lens center position B of the CCD camera 2a and the corner apex position D of the reticle 1 and the positional deviation between the lens center position A of the CCD camera 2b and the reticle corner apex position C. Based on and, the positional deviation of the entire reticle 1 is obtained. At this time, when the central position of the reticle 1 in the state where there is no positional deviation is O and the central position of the reticle 1 in the state where there is a positional deviation is P, the positional deviation amount (X, Y, θ) is shown in FIG. It can be obtained by the coordinate transformation shown.

In FIG. 4, when the shape of the reticle 1 in the state where there is no displacement is a square and one side thereof is 2k, the coordinate values of the points A, B, C and D are as follows. A (0,0), B (0,2k), C (x1, y1), D
(X2, 2k + y2) At this time, the center position O of the reticle with no positional deviation.
The coordinates of can be represented by O (k, k). Using these conditions, the coordinates of the center position P of the reticle 1 in a position-shifted state are obtained. Here, when the midpoint of the straight line CD in FIG. 4 is E, the coordinates are expressed by E ((x1 + x2) / 2, (2k + y1 + y2) / 2). Further, the hatched 2 shown in FIG.
The right-angled triangles have a congruent relationship, and the lengths of the two sides sandwiching the right-angled triangle are obtained as follows. Long side: (2k-y1 + y2) / 2 Short side: (x1 -x2) / 2 From this, the coordinates of the point P (Xp, Yp) are Xp = (x1 + x2) / 2 + (2k-y1 + y2) / 2Yp = (2k + y1 + y2) / 2 + (x1−x2) / 2, and the coordinates of the point P (Xp, Yp) are as follows by rearranging each expression. P (k + (x1 + x2-y1 + y2) / 2, k + (x1-x2
+ Y1 + y2) / 2) The rotational deviation α of the reticle 1 in the θ direction at this time can be expressed by Tan α = (x1−x2) / (2k−y1 + y2).

From the above, the positional deviation amount of the reticle 1 (X,
Y, θ) can be obtained by X = (x1 + x2−y1 + y2) / 2 Y = (x1−x2 + y1 + y2) / 2 θ = arctan ((x1−x2) / (2k−y1 + y2)) .

Next, a procedure for correcting the positional deviation of the reticle 1 based on the positional deviation amount (X, Y, θ) obtained by the arithmetic unit 11 as described above will be described with reference to FIG.
First, the corners of the reticle 1 are imaged by the CCD cameras 2a and 2b in the transport section, and the positional shift amount (X, Y, θ) is calculated by the calculation section 12. Based on this position shift amount (X, Y, θ), the controller 12 sets the movement amount (X, Y, θ) corresponding to the position shift amount (X, Y, θ) in advance using the XY stage 3 and the θ stage 4 as initial correction amounts. Y, θ)
Drive commands for driving only from the initial position
Output to 4. In this state, the reticle 1'is transferred to the positioning stage S. Next, an operation command for moving the positioning stage S by (-X, -Y,-[theta]) is output from the control unit 12, the drive units 13 and 14 move by a predetermined amount, and return to the initial position. As a result, the positional deviation of the reticle 1 during transportation is completely canceled on the positioning stage S, and the alignment of the reticle 1'is completed.

Here, a modification of the above-mentioned image pickup means will be briefly described. In this embodiment, the CCD cameras 2a and 2b
Although two units were arranged in the width direction perpendicular to the reticle transport direction, one CCD camera that can move in the direction orthogonal to the transport direction was placed, and two corners were imaged while the reticle was stopped. It is also possible to perform the above-mentioned coordinate calculation based on the respective image pickup information. Further, when the outer contour of the reticle can be accurately recognized on the image, it is possible to calculate the positional deviation of the reticle by imaging one corner and two sides sandwiching the corner. Further, the image pickup means is not limited to the two-dimensional CCD camera, and various means such as a linear CCD sensor and an image pickup tube can be applied.

[0022]

As is apparent from the above description, according to the present invention, a substrate such as a reticle can be positioned without being moved by a position adjusting member or the like, and positioning can be flexibly performed on various substrates. It is possible. further,
Since the contact portion is remarkably reduced, the dust generation can be remarkably reduced, and the contamination of the reticle and the like can be minimized.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a schematic configuration of an embodiment of a substrate position correction device according to the present invention.

FIG. 2 is an explanatory diagram showing an example of an image obtained by the image pickup means of the present invention.

FIG. 3 is a conceptual diagram showing a misaligned state of a reticle.

FIG. 4 is an explanatory diagram illustrating a principle of calculating a positional deviation amount (X, Y, θ) of a reticle.

5 is an explanatory diagram showing a positional deviation correction state by the substrate position correction device in FIG. 1. FIG.

FIG. 6 is a schematic configuration diagram showing an example of a conventional reticle pre-alignment mechanism.

[Explanation of symbols]

 1 Reticle 2a, 2b CCD camera 3 XY stage 4 θ stage 10 Image signal processing unit 11 Computing unit 12 Control unit 13, 14 Driving unit

Claims (1)

[Claims] 1. An image pickup means for picking up an image of a corner of a rectangular substrate held on a substrate transfer member at a predetermined position, and a signal from the image pickup means is image-processed to hold the substrate on the substrate transfer member. A substrate holding position detecting means for detecting a position, and a positional deviation amount for calculating a positional deviation amount between the substrate holding position detected by the substrate holding position detecting means and the proper holding position of the substrate defined on the transport member. Before the calculation means and the substrate is transferred to the positioning stage,
Stage control means for moving the positioning stage from an initial position by a movement amount equal to the positional deviation amount, and after returning the positioning stage to the initial position after the substrate is transferred to the positioning stage at this position, A substrate position correction device having.