Method of driving mask stage and method of mask alignment

Abstract

In a scanning-type projection exposure system, curvature of a movable mirror that is used to measure mask stage coordinate positions is determined while the mask stage is moved in the scanning direction, by measuring coordinate positions, perpendicular to the scan direction, of the mask stage and of a mask mark elongated in the scan direction. The results of the measurements are used for correcting or compensating positional deviation during scanning. Rotational deviation of a mask pattern area is determined and is corrected or compensated. Also, a mask is aligned with respect to a coordinate system of the mask stage as pre-processing for exposure, using a mask alignment mark having two crossing linear patterns and determining a coordinate position of the crossing point by moving the mask relative to an observation area.

Description

BACKGROUND OF THE INVENTION1. Field of the InventionThe present invention relates to a method of driving a mask stage and a method of mask alignment. More particularly, the present invention relates to a method of driving a stage, which is suitably applied to a case where a reticle-side stage is driven in a scan direction in a slit-scan exposure type projection exposure apparatus, and a method of mask alignment in the projection exposure apparatus.2. Related Background ArtWhen a semiconductor element, a liquid crystal display element, a thin film magnetic head, or the like is manufactured in a photolithography process, a projection exposure apparatus for transferring a pattern on a photomask or a reticle (to be generally referred to as a "reticle" hereinafter) onto a substrate (a wafer, glass plate, or the like) coated with a photosensitive material is used.As a conventional projection exposure apparatus, a step-and-repeat type reduction projection exposure apparatus (stepper) for s...

AI Technical Summary

Benefits of technology

The present invention has been made in consideration of the above situation, and has as its object to provide a method of driving a stage, which can prevent generation of an intra-shot distortion even when a movable mirror provided to a stage at the side of reticle (mask) has a curve in a slit-scan exposure type exposure apparatus.

moving the mask stage in the direction perpendicular to the scan direction so as to correct the curved amount of the movable mirror when a transfer mask is scanned via the mask stage in the scan direction with respect to the predetermined shaped illumination area.

According to the first invention, since the curved amount of the movable mirror is measured with reference to the measurement mark provided to the mask, and the measured curved amount is corrected in exposure, even when the movable mirror provided to the mask stage on the side of the mask has a curve, generation of an intra-shot distortion at the substrate side can be prevented.

According to the second invention, since the curved amount of the movable mirror is measured with reference to the mask guide, when the straightness of the mask guide is good, the curve amount of the movable mirror can be quickly and easily measured, and the measured curved amount can be corrected in exposure.

The present invention has been made in consideration of the above situation, and has as its object to provide an alignment method which can align a reticle (mark) at high speed with high accuracy in a slit-scan exposure type projection exposure apparatus.

According to the third invention, when the mask stage is driven with respect to the observation area of the observation means so as to obliquely scan the mask, the coordinate position of the crossing point of the two linear patterns of the alignment mark on the mask can be measured by the open-loop control. Therefore, mask alignment can be realized at high speed with high accuracy.

Problems solved by technology

Furthermore, when the characteristics of an intra-shot distortion vary from one exposure apparatus to another, such a variation results in a matching error between different layers on the wafer.

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