Method for measuring alignment accuracy in a step and repeat system utilizing different intervals

摘要

A method for measuring alignment accuracy in a step and repeat system which includes projecting an array of rows and columns of grating features onto a wafer coated with a resist using a first stepping distance and using an increased exposure dosage from row to row of said array; projecting the same array over the first but using a different stepping distance along the rows and also a sufficient offset in the starting positions of the first and second exposures to form a phase difference between the two projection exposures which will result in a complementary alignment of the two exposures at least one column in the array.