SHAPE ACCURACY IMPROVEMENT USING A NOVEL CALIBRATION APPROACH

摘要

Determining the systematic error of an instrument that measures features of a semiconductor wafer which a symmetric corrector is calculated by taking the average over all measurement signatures at each load angle. The symmetric corrector is successively rotated to the same angle as a front shape measurement and subtracted, yielding a calibrated wafer data set (80). A wafer mean is computed by averaging these calibrated wafer shape measurements (82). When the wafer mean is substracted from the individual front side corrected shape measurements, a set of shape residual maps for each load angle results (84). The average of the aligned residuals is the asymmmetric error (86). The systematic error is the sum of the symmetric and asymmetric errors (90).