JPH0382013A - Control method of positioning of stage - Google Patents

Abstract

PURPOSE:To reduce cost and the burden of a delivery data in the manufacturing process of a stage, and to enable positioning with high accuracy without the constraint of severe environmental conditions by measuring an attitude before and after the positioning of the stage and correcting and controlling an Abbe error generated by the tilt-displacement of the stage on the basis of the variation section of the attitude during that time. CONSTITUTION:The attitude of a mirror 5 for a laser interferometer placed on direct- acting stages 6, 8 through a tilt stage 7 is measured, and a first measured value is acquired. The positioning of the direct-acting stages 6, 8 is controlled by using laser beams applied to the mirror 5 for the laser interferometer at a preceding time, the attitude of the mirror 5 for the laser interferometer is measured again, and a second measured value is obtained. The quantity of the variation of the attitude of the mirror 5 for the laser interferometer is computed on the basis of the first and second measured values at the preceding time, and the tilt stage 7 is controlled on the basis of the quantity of the variation of the attitude at the preceding time in order to correct an Abbe error. When the quantity of the variation of the attitude at the preceding time is kept outside a specified tolerance, the tilt stage 7 is controlled on the basis of the quantity of the variation of the attitude.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a stage positioning control method, and in particular, a method for controlling stage positioning, in which a pattern formed on a mask or a reticle is printed on a semiconductor wafer in order by step-and-repeat for each shot. The present invention relates to a positioning control method for an XY stage that is applied to a so-called stepper and moves a semiconductor wafer in each of the X and Y directions.

[Conventional technology]

Conventionally, in an XY stage that moves a semiconductor wafer in each of the X and Y directions in a stepper, its position is usually measured using a laser light wave interferometer (hereinafter referred to as a laser interferometer).

Length measurement using a laser interferometer is performed by placing a mirror for the laser interferometer integrally with the wafer chuck on the XY stage and reflecting the laser beam with this mirror.The stage control device controls the measurement of the laser interferometer. The stage is positioned based on the long value.

By the way, in such a device, the Atsube length and the pitching of the XY stage are determined in two directions: the position where the laser beam hits the laser interferometer mirror (measurement position) and the position where the wafer is held on the wafer chuck (control target position). Alternatively, the positioning accuracy of the XY stage may deteriorate due to Atsube errors caused by both rolling. Conventionally, such a decrease in accuracy has been negligible, or has been dealt with by reducing the length of the stage structure as much as possible.

(The problem that the invention is trying to solve) However,
In recent years, when stages are required to be positioned with extremely high precision, conventional methods are no longer sufficient. In addition, the wafer chuck can be used with multiple axes, such as X, Y,
When moving in six directions, including the Z-axis direction and the directions around each of the x, y, and z axes, shorten the length and improve the linear accuracy of each stage in the X, Y, and Z axes. If such measures are taken only on the device structure side, the following problems will occur.

(1) In order to obtain high positioning accuracy, it is necessary to make each stage mechanism extremely accurate in order to improve the linear movement accuracy of the stage, which increases the cost and delivery time in the manufacturing process.

(2) Restrictions on the environmental conditions around the stage become extremely strict.

The present invention has been made in view of these circumstances, and its purpose is to provide an extremely highly accurate stage positioning control method and apparatus.

Another object of the present invention is to provide a stage positioning control method that reduces costs and delivery times in the stage manufacturing process and enables highly accurate positioning without the constraints of severe environmental conditions.

(Means and operations for solving the problem) In order to achieve the above object, the stage positioning correction control method according to the present invention measures the posture of the stage before positioning and the posture after positioning, and The present invention is characterized in that the Atsube error caused by the tilt displacement of the stage is corrected and controlled based on the variation of the stage.

Further, the stage positioning correction control device according to the present invention includes:
A position measuring means, such as a laser interference needle, for positioning the stage, and an attitude displacement measuring means, such as a position sensor, a collimator, or a tilt sensor using a laser interference needle, for measuring the attitude displacement between the measurement position and the control position. The present invention is characterized by comprising means for correcting and controlling an Atsube error caused by a tilt shift of the stage based on a change in the attitude of the stage before and after positioning.

With this configuration, it is possible to know the amount of pitching at the stage position measurement point, and also the amount of pitching displacement that occurs during positioning, and it is possible to reproduce the posture based on a predetermined control sequence. Thereby, it is possible to improve the positioning accuracy due to the long length, which was guaranteed only within the range of the linear movement accuracy of the stage.

(Example) The present invention will be described below in a so-called stepper that prints a pattern formed on a mask or reticle by step-and-repeat for each shot on a semiconductor pattern.
An example will be explained in which the semiconductor query is applied to a stage that moves in each of the X and Y directions.

In Figures 1 to 3, l is a laser interferometer for X-axis length measurement, and 2
3 is a laser interferometer for length measurement of the X-axis pitching component (rotation component around the Y-axis), 3 is a laser interferometer for Y-axis length measurement, and 4 is a laser for Y-axis pitching component (rotation component around the X-axis) length measurement. It is an interferometer. Laser light from each laser interferometer is reflected by a laser interference mirror 5. Yolar 5 is laser interferometer 1
．． a reflective surface 5ah substantially parallel to the YZ plane for reflecting the laser beam from 2; a reflective surface 5b substantially parallel to the xZ plane for reflecting the laser beam from the laser interferometer 3°4;
have. As shown in FIG. 2, the interferometer 2.4 irradiates the mirror 5 with two laser beams spaced apart in the
The posture in the rotational direction around the axis and the posture of the reflective surface 5b in the rotational direction around the X-axis are detected.

6 is an X stage, 7 is a tilt stage, 8 is a Y stage, and 18 is a wafer chuck for holding the semiconductor wafer 19. The Y stage 8 is moved in the Y-axis direction with respect to a base (not shown) by a Y-stage drive means 16, and
The stage 6 is moved in the X-axis direction relative to the Y stage 8 by the X stage drive means 15. The tilt stage 7 includes three piezo stacks 7a that move the wafer chuck 18 in the X-axis direction relative to the X stage 6.

7b and 7c, each piezo stack 78
- 7c are arranged at equal intervals on the circumference around the wafer chuck 18 in the XY plane, and the wafer holding surface of the wafer chuck 18 is tilted with respect to the XY plane by means of screws that are driven by different amounts. is possible. Further, the wafer chuck 18 is moved in the X-axis direction.

The laser interference mirror 5 is integrally constructed with the wafer chuck 18, and the wafer chuck 18 is integrally tilted with respect to the X stage 6.The tilt stage 7 is configured as a tilt stage drive. Each drive means 15, 16, 17 performs control based on commands from a controller 30, and the controller 30 processes the measured values of each laser interferometer 1.2, 3.4. Together, they control this entire stage device.

In FIG. 3, reference numeral 14 indicates the upper surface ε of the semiconductor wafer 19 held by the wafer chuck 18 in the X-axis direction, which is substantially the same position, and is the control target point 14 which is the target of actual control. The distance in the X-axis direction between the points where the laser beam from the Hilaser interferometer 1 hits the reflective surface 5a of the mirror 5 is the Atsube length 9. 12 is the posture of the mirror 5 before the stage 6.8 starts moving, and 13 is the pitching of the stage 6 and the stage 8 after positioning the stage 6.8.
It shows the attitude of the mirror 5 that has changed due to the tilt displacement caused by the rolling of the mirror 5. 10 is the Atsube error in the X-axis direction caused by the tilt displacement, 11 is the tilter posture 12 Hischishiro before the start of the movement of stage 6.8,
This is a tilt angle indicating the variation in the X-axis direction between mirror postures 13 after positioning of 8. Note that the same applies to the Y-axis direction, so the explanation will not be repeated here.

When stage 6.8 is positioned in the X and Y directions,
Due to the pitching of the X stage 6 and the rolling component of the Y stage 8 (both rotational components around Y@), an Abbe error of 1-0 occurs in the X-axis direction. Regarding the Y@ direction, the pitching component of the Y stage 8 and the rolling component of the X stage 6 (both rotational components around the X axis) &
:A similar Atsube error occurs. Since the Atsube length 9 is known, the error amount of this Atsube error 10 is determined by the pitching component length measurement laser interferometer 2 in the X-axis direction. By multiplying, we can find ε. The same calculation formula can be used for the Y-axis direction.

In this embodiment, positioning correction control is performed in accordance with the procedure shown in the flowchart of FIG.

First, in step S1, the mirror 5 is detected by the interferometer 2 (4).
The reflecting surface 5a (5b), that is, the posture 12 of the wafer chuck 18 is measured, and this measured value is stored in the memory in the controller 30 in step S2. After this controller 3
0 is the X, Y stage drive means 1 in step S3.
5.16, command the movement of X and Y stages 6.8,
Start the movement of Y stage 6.8. Step S4
Now, X is determined based on the measured values of the laser interferometer 1.3 for measuring the X and Y positions of the wafer chuck 18.

The Y stage drive means 16.18 is controlled to position the X and Y stages 6.8 so that the measured values of the laser interferometers 1 and 3 correspond to the commanded position.

After this, in step S5, the reflective surface 5a (5
The posture 13 of b) is measured again by the laser interferometer 2 (4), and in step S6, the stage 6.
A tilt angle 11, which is the attitude change of the reflecting surface 5a (5b) before and after the movement of 8, is calculated. In step S7, it is determined whether or not this attitude variation (tilt angle) 11 is within a predetermined tolerance. When the tilt error occurring between the control target points 14 is negligible, positioning by the X and Y stages 6.8 is completed.

On the other hand, if the attitude variation 11 is outside the tolerance, the process proceeds to step S8, and the controller 30 causes the tilt stage drive means 17 to move the tilt stage 7 by the attitude variation 1.
A command is given to drive by an amount that corrects 1-. As a result, the tilt stage drive means 17 causes the tilt stage 7 to taile the wafer chuck 18 and the mirror 5 integrally, returning the mirror 5 from the posture 13 to the posture 12. By this tailing, the laser interferometer 1 (3) Since the measured value of the interferometer 1 (3) may change, the controller 30 then calculates the change (deviation) in the measured value of the interferometer 1 (3) with respect to the command position in step S9.
is calculated, and the process returns to step 1 to readjust the position of the X and Y stages 6.8 by this amount. After that, the same operation as described above is repeated, and the determination in step S7 is YES.
When the position reaches S, the positioning of the X and Y stages 6.8 is completed.

In the above-mentioned embodiment, the attitude of the mirror 5 is measured by the laser interferometer 2.4, but this is achieved by, for example, providing a position sensor at a position that is integrally displaced with the mirror 5, thereby detecting the incident laser beam. Changes in posture may be detected by detecting changes in the position of the light, or may be detected using a known collimator.

(Effects of the Invention) As explained above, according to the present invention, since the Atsube error caused by the Atsube length is corrected based on the attitude fluctuation of the stage before and after positioning, the required stage accuracy specifications It is possible to reduce burdens such as costs and delivery times in the manufacturing process of manufacturing a positioning device that satisfies the above requirements, and to realize highly accurate positioning without the constraints of severe environmental conditions.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a schematic configuration of a stage positioning device according to an embodiment of the present invention using a laser interference needle for pitching component length measurement, and FIG. 2 is a side view of the device shown in FIG. 1. Figure iE3 is a side view mainly showing the arrangement of the laser interferometer for pitching component length measurement. FIG. 4 is a flowchart showing the control sequence of the apparatus of this embodiment. 1-Laser interferometer for X-axis length measurement, 2-Laser interferometer for X-axis pitching component length measurement, 3...Laser interferometer for Y-axis length measurement, 4...Laser interferometer for Y-axis pitching component length measurement , total,
5... Cler 6... X stage, 7... Tilt stage, 8... Y stage, 15... X stage drive means, 16... Y stage drive means,
18... Wafer chuck, 19... Sea urchin eight, 30.
... Controller% 1 Figure Figure Figure

Claims (3)

[Claims] (1) A step of measuring the attitude of a laser interferometer mirror placed on a linear motion stage via a tail ink stage to obtain a first measurement value, and a laser beam irradiated to the laser interferometer mirror. controlling the positioning of the linear motion stage using the linear motion stage; after positioning the linear motion stage, measuring the attitude of the laser interferometer mirror again to obtain a second measurement value; A stage characterized by comprising the steps of: calculating an amount of attitude variation of a mirror for a laser interferometer based on a measured value; and controlling the tailing stage based on the amount of attitude variation in order to correct an Atsube error. Positioning control method. (2) The stage positioning control method according to claim 1, wherein when the amount of attitude variation is outside a predetermined tolerance, the tailing stage is controlled based on the amount of attitude variation. (3) When the tailing stage is controlled based on the amount of attitude variation, positioning control of the linear motion stage is performed again using a laser beam irradiated to the laser interferometer mirror. The stage positioning control method described.