Method for measuring and calibrating centroid of coarse stage of photolithography tool

A method for measuring and calibrating a centroid of a coarse stage of a photolithography tool by means of measuring an offset of the centroid relative to a midpoint of the coarse stage, comprising the steps of:

• step 1, individually performing closed-loop controls with a controller on parameters of three horizontal degrees of freedom (X, Y, Rz) of the coarse stage and converting the parameters into coordinates in a coordinate system of the coarse stage, wherein X and Y are two directions orthogonal to each other within a horizontal plane, and Rz is rotation about a vertical axis within the horizontal plane;
• step 2, determining an initial X-direction range and an initial Y-direction range for the centroid in the coordinate system of the coarse stage and equally dividing each of the initial X-direction range and the initial Y-direction range into N parts, designating dividing points of the initial X-direction range as X-direction eccentricities Δx's, and designating dividing points of the initial Y-direction range as Y-direction eccentricities Δy's, wherein N is a natural number;
• step 3, obtaining N Rz-direction positional deviations by conducting a calibration calculation with the controller based on the X-direction eccentricities Δx's, comparing a minimum Rz-direction positional deviation derived from the N Rz-direction positional deviations with a preset Rz-direction positional deviation threshold, if the minimum Rz-direction positional deviation is smaller than the preset Rz-direction positional deviation threshold, designating an X-direction eccentricity Δx corresponding to the minimum Rz-direction positional deviation as an actual X-direction eccentricity and proceeding to step 5, and otherwise designating an updated X-direction range whose limits are selected as X-direction eccentricities adjacently in front of and behind the X-direction eccentricity corresponding to the minimum Rz-direction positional deviation, respectively, equally dividing the updated X-direction range into N parts, designating dividing points of the updated X-direction range as updated X-direction eccentricities Δx's, and repeating step 3;
• step 4, obtaining N Rz-direction positional deviations by conducting a calibration calculation with the controller based on the Y-direction eccentricities Δy's, comparing a minimum Rz-direction positional deviation derived from the N Rz-direction positional deviations with a preset Rz-direction positional deviation threshold, if the minimum Rz-direction positional deviation is smaller than the preset Rz-direction positional deviation threshold, designating a Y-direction eccentricity Δy corresponding to the minimum Rz-direction positional deviation as an actual Y-direction eccentricity and proceeding to step 5, and otherwise designating an updated Y-direction range whose limits are selected as Y-direction eccentricities adjacently in front of and behind the Y-direction eccentricity corresponding to the minimum Rz-direction positional deviation, respectively, equally dividing the updated Y-direction range into N parts, designating dividing points of the updated Y-direction range as updated Y-direction eccentricities Δy's, and repeating step 4;
• and
• step 5, deriving the offset of the centroid according to results of steps 3 and 4,
• wherein, step 3 is carried out prior to, subsequent to, or concurrently with step 4.