METHODS AND APPARATUS FOR CALCULATING SUBSTRATE MODEL PARAMETERS AND CONTROLLING LITHOGRAPHIC PROCESSING

摘要

Offline metrology measurements 804 are performed on wafer substrates that have been subjected to lithographic processing. Model parameters 808 are calculated 806 by fitting the measurements to an extended high-order substrate model defined 802 using a combination of basis functions that include an edge basis function related to a substrate edge. The radial edge basis function may be expressed in terms of distance from a substrate edge. The edge basis function may for example be an exponential decay function or a rational function. Lithographic processing of a subsequent substrate is controlled 820 using the calculated high-order substrate model parameters 808, in combination 81 8 with low-order substrate model parameters 816 obtained by fitting 814 inline measurements 812 to a low order model 810.