JPS5487249A - Positioning device - Google Patents

Abstract

PURPOSE: To accomplish the positioning operation accurately at a high speed by setting the coefficients of displacement operating equations in a register so that the displacement of a stage may be controlled on the basis of the values stored in the register.

CONSTITUTION: The coordinates of the marks M₁ to M₄, which are formed at spacings a and b in the perpendicular directions x and y on a wafer, are read out to determine the differences ΔX₁ to ΔX₄ and ΔY₁ to ΔY₄ of the wafer placed in reference position from the coordinates of the marks M₁ to M₄ of the wafer. Then, the parallel displacement distances A and E, rotational error coefficients C and F, varying coefficients of the wafer size B and G, and distrosion error coefficients D and H are calculated on the basis of Equations III to X. Those coefficients A to H are stored in the register so that the displacements corresponding to the coordinates X_i and Y_i of the designated positions of the marks M₁ to M₄ of the wafer, which is reinserted after the retreatment, are calculated on the basis of Equations I and II by means of adding and multiplying circuits. Then, the movement signals required for the stage, on which the wafer is placed, are determined to make it possible to effect the positioning operations accurately at a high speed.

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