METHOD FOR MANAGING SUPERPOSITION ACCURACY AND SUPERPOSITION ACCURACY MEASURING INSTRUMENT THEREFOR

摘要

PROBLEM TO BE SOLVED: To decrease the number of lots which are heretofore judged to be out-of-specifications and are sent to a regeneration stage, to improve the reliability in semiconductor device production and to reduce a cost by using a specific management method with specific superposition accuracy capable of executing correct error management without depending on sampling layouts. SOLUTION: A partial number of exposure fields formed in the same number on a substrate are sampled and the superposition errors generated therein are measured. The measured superposition errors are separated to a linear error Einter( L) and a non-linear error Einter( N) . The average value (x) of the resulted liner error Einter( L) and the max./min. value Einter- MAX/ MIN( L) thereof are determined from the resulted error. The 3σinter( N) of the nonlinear error Einter( N) is determined from this error. Next, the total error Einter- TOTAL between the fields is determined by the equation: Einter- TOTAL =|x|+|Einter- MAX/ MIN( L) |+3σinter( N) . The determined total error Einter- TOTAL between the fields and the management target value are compared.