| 摘要 |
PROBLEM TO BE SOLVED: To determine the systematic error of an instrument that measures features of a semiconductor wafer. SOLUTION: A method for determining the symmetric error of a measurement instrument that measures features of a semiconductor wafer includes the step of yielding a front data set and a back data set for each angle by collecting sensor data from measurement runs on front and back surfaces of a wafer while the wafer is oriented at different angles to the instrument for each run, yielding an averaged wafer shape for each load angle by subtracting the reflected back data from the front data for each wafer angle and by dividing the result by two, and yielding an instrument signature for each load angle by adding the reflected back data to the front data and by dividing the result by two. The symmetric corrector is calculated by taking the average over all instrument 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. A wafer mean is computed by averaging these calibrated wafer shape measurements. When the wafer mean is subtracted from the individual front side corrected shape measurements, a set of shape residual maps for each load angle results. The average of the aligned residuals is the asymmetric error. The systematic error is the sum of the symmetric and asymmetric errors. COPYRIGHT: (C)2008,JPO&INPIT |
