JP2002280440A - Method for automatically controlling positional correction of rotary stage in inspection instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection instrument which has high controllability and high inspection precision by measuring a positional relation between a line sensor camera and a rotary stage, and between the camera and a survey object work automatically and controlling the positional relation between the rotary stage and the line sensor camera based on measured data automatically. SOLUTION: This method for automatically controlling the positional correction of the rotary stage in the inspection instrument has the line sensor camera 3 for detecting the position of the rotary stage 1, an arithmetic means 5 for leading the positional relation between the stage 1 and the survey object work 2 from image pickup data obtained by the camera 3, and actuators such as piezo elements 6a and 6b for driving the stage 1 in a horizontal direction and a vertical direction based on an arithmetic result; and controls the positional relation between the stage 1 and the camera 3 automatically.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary stage automatic position correction control method in an inspection apparatus for imaging a work to be inspected mounted on a rotary stage with a line sensor camera.

[0002]

2. Description of the Related Art Conventionally, an inspection system as shown in FIG. 7 has been employed as a method for detecting a defect of a work to be inspected. In FIG. 7, reference numeral 1 denotes a rotary stage, 2 denotes a work to be inspected, 3 denotes a line sensor camera, and 4 denotes an image processing means. When the rotary stage 1 rotates, the inspection target work 2 is imaged by the line sensor camera 3 and the inspection is performed by the image processing means 4. In such an inspection method, the positional relationship between the rotary stage 1 and the line sensor camera 3 and between the line sensor camera 3 and the inspection target work 2 is a major factor in determining the inspection accuracy.

[0003]

However, in the inspection system as described above, the rotary stage 1 and the line sensor camera 3 and the rotary stage 1 and the target work 2 are used.
Since there is no means for automatic measurement and automatic adjustment of the positional relationship between the rotating stage 1 and the workpiece 2 to be inspected,
When a positional deviation occurs between the positions, the position measurement and the position adjustment are performed in an off-line operation, which requires a large amount of time, and the inspection accuracy is not always accurate.

In view of the above-mentioned conventional problems, the present invention automatically measures the positional relationship between a line sensor camera and a rotating stage and a work to be inspected, and automatically determines the positional relationship between the rotating stage and the line sensor camera based on measurement data. It is an object of the present invention to provide an inspection device having high controllability and high inspection accuracy by performing the control.

[0005]

According to the present invention, there is provided a rotary stage automatic position correction control method in an inspection apparatus, comprising: a line sensor camera for detecting a position of the rotary stage; Operation means for deriving the positional relationship with the workpiece, and actuators such as piezo elements that drive the rotary stage in the horizontal and vertical directions based on the calculation results, and automatically control the positional relationship between the rotary stage and the line sensor camera. Is what you do.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention described in claim 1 of the present invention relates to an inspection apparatus for mounting a work to be inspected such as a semiconductor wafer on a rotary stage and taking an image using a line sensor camera. The position of the rotary stage is rotated based on the means for calculating and storing the deviation of the workpiece to be inspected at the rotation angle of the rotary stage from the image data of the rotary stage and the workpiece to be inspected as a position correction value of the rotary stage, and the position correction value. Inspection characterized by having an actuator that automatically corrects for each angle, and by controlling the position of the rotary stage based on the position correction value so that the rotation center of the inspection target work with respect to the line sensor camera is always constant. This is a method of automatically correcting the position of the rotating stage in the device, and the inspection target mounted on the rotating stage If a positional deviation is recognized between the rotation center of the rotating stage and the rotating stage, the deviation of the work to be inspected at the rotating angle of the rotating stage is calculated as a position correcting value of the rotating stage, and the rotation is calculated based on the position correcting value. Since the stage position is automatically corrected, the rotation center of the inspection target work with respect to the line sensor camera is always constant,
In addition to improving the inspection accuracy, compared to the conventional method of performing position measurement and position adjustment as offline work,
This has the effect of greatly shortening the inspection time and providing a highly accurate inspection device.

According to a second aspect of the present invention, the length b between the edge of the work to be inspected and the center of the rotary stage at the radius a of the work to be inspected and the rotation angle θ of the rotary stage is obtained, and (B−a)
cos θ, and the deviation in the vertical direction is obtained by (ba) sin θ, and has an operation of easily and accurately calculating a position correction value.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a rotary stage automatic position correction control of the inspection apparatus of the present invention will be described below with reference to FIGS.
This will be described with reference to FIG.

In the figure, 1a is the center of the rotary stage,
2a is the center of the inspection work, 5 is the position calculating means, 6a and 6
b is a piezo element. In addition, the same components as those of the conventional example are denoted by the same reference numerals, and description thereof is omitted.

FIG. 1 is an external perspective view of the inspection system. In FIG. 1, when rotating a rotary stage 1, an image of a work 2 to be inspected is taken using a line sensor camera 3, and a position calculating means 5 rotates the rotary stage 1 and the line sensor camera 3, and the line sensor camera 3 and a work 2 to be inspected.
Is calculated, and the horizontal and vertical positional relationships between the rotary stage 1 and the line sensor camera 3 can be automatically corrected by the piezo elements 6a and 6b. FIG. 2 is a top view of the inspection system when the rotation centers 1a and 1b of the rotation stage 1 and the inspection target work 2 coincide with each other.

In this configuration, the rotary stage 1 is rotated, the edge of the work 2 to be inspected is imaged by the line sensor camera 3, and the image of the edge of the work 2 to be inspected is represented by the vertical axis.
Plot the rotation angle on the horizontal axis. As shown in FIG. 2, when the center 1a of the rotary stage 1 and the center 2a of the work 2 to be inspected coincide with each other, the plotted diagram shows the relationship between the rotation angle and the work 2 to be inspected as shown in FIG. Is a constant value a which is the radius of the workpiece 2 to be inspected.
And make a straight line.

However, as shown in FIG.
Center 1a of rotary stage 1 and center 2 of work 2 to be inspected
If a does not match, the plot is a curve as shown in FIG.

In FIG. 3, a constant value at which the edge image of the work 2 to be inspected becomes a straight line with respect to the rotation angle θ of the rotary stage 1 is a. Let b be the value at which
a is the length between the edge of the work 2 to be inspected and its center 2a, and b is the length between the edge of the work 2 to be inspected and the center 1a of the rotary stage 1 with respect to the rotation angle. The shift x in the horizontal direction and the shift y in the vertical direction of the inspection target work 2 with respect to the center 1a of the rotary stage 1 at the rotation angle θ are expressed by the following equations, respectively, as is clear from FIG.

The horizontal shift x = (ba) cos θ The vertical shift y = (ba) sin θ The calculation of the horizontal shift and the vertical shift based on the above equation is calculated by the rotation angle of the rotary stage 1. θ is in the range of 0 to 360 degrees using the position calculation means 5, and the horizontal displacement x and the vertical displacement y are stored as position correction values of the rotating stage, and are set in the horizontal and vertical directions. The rotating stage 1 is driven by the piezo elements 6a and 6b based on the position correction value stored when the rotating stage 1 is at the rotation angle θ, and this operation is performed in the range of 0 ° to 360 ° to obtain a line. Control can be performed such that the rotation center of the work to be inspected with respect to the sensor camera is always constant.

As described above, according to the present invention, it is possible to automatically control the positional relationship between the rotary stage of the inspection device and the line sensor camera.

[0016]

According to the present invention, the displacement of the work to be inspected at the rotation angle of the rotary stage is calculated as a position correction value of the rotary stage, and the position of the rotary stage is automatically corrected based on the position correction value. The rotation center of the workpiece to be inspected with respect to the sensor camera is always constant,
In addition to improving the inspection accuracy, compared to the conventional method of performing position measurement and position adjustment as offline work,
A quick and highly accurate inspection apparatus can be provided, and the time required for acquiring the positional relationship between the rotary stage and the line sensor camera and the positional relationship between the line sensor camera and the work to be inspected can be reduced.

[Brief description of the drawings]

FIG. 1 is an external perspective view of an inspection system according to an embodiment of the present invention.

FIG. 2 is a diagram viewed from above when the rotation centers of the inspection system according to the embodiment match.

FIG. 3 is a plot diagram of a line sensor camera image and a rotation angle in the case of FIG. 2;

FIG. 4 is a view seen from above when the rotation centers of the inspection system of the embodiment are not coincident.

FIG. 5 is a plot diagram of a line sensor camera image and a rotation angle in the case of FIG. 4;

FIG. 6 is an explanatory diagram for calculating a shift when the rotation centers do not match.

FIG. 7 is a perspective view showing an example of a conventional inspection system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotation stage 2 Workpiece to be inspected 3 Line sensor camera 4 Image processing means 5 Position calculation means 6 Piezo element

Continued on the front page (72) Inventor Katsuhiro Kida 1006 Kazuma Kadoma, Kazuma City, Osaka Prefecture F-term (reference) 2F065 AA03 AA12 BB03 CC19 DD06 FF42 JJ02 JJ25 LL57 MM04 PP13 QQ13 QQ17 QQ23 QQ25 5F031 JA02 JA29 JA32 JA36 KA11 LA10 MA33 5H303 AA06 DD14 GG14 HH01

Claims (2)

[Claims] An inspection apparatus that mounts a workpiece to be inspected, such as a semiconductor wafer, on a rotary stage and captures an image using a line sensor camera, wherein the rotary stage is obtained from image data of the rotary stage and the workpiece to be inspected by the line sensor camera. Means for calculating and storing the displacement of the workpiece to be inspected at the rotation angle as a position correction value of the rotation stage; and an actuator for automatically correcting the position of the rotation stage for each rotation angle based on the position correction value. A position correction based on the position correction value, thereby controlling the rotation center of the work to be inspected with respect to the line sensor camera to be always constant. 2. The length b between the edge of the work to be inspected and the center of the rotary stage at the radius a of the work to be inspected and the rotation angle θ of the rotary stage is determined. 2. The method according to claim 1, wherein a) cos θ and the deviation in the vertical direction are obtained by (ba) sin θ.