Emf correction model calibration using asymmetry factor data obtained from aerial images or a patterned layer

A computer-implemented method of generating an electromagnetic field (EMF) correction boundary layer (BL) model corresponding to a mask, comprising using a computer to perform a method, the method including:

• (a) determining asymmetry factor data from aerial image measurements of a plurality of different gratings representative of features provided on a mask, the aerial image measurements having been made at a plurality of different focus settings, the aerial image measurements including X polarization measurements obtained by using light of an X polarization normal to a direction in which lines of the gratings extend, and Y polarization measurements obtained by using light of a Y polarization parallel to the direction in which the lines of the gratings extend;
• and
• (b) determining normal boundary layer model parameters of an EMF correction BL model corresponding to the mask by fitting to the asymmetry factor data corresponding to the X polarization measurements, and determining parallel boundary layer model parameters of the EMF correction BL model corresponding to the mask by fitting to the asymmetry factor data corresponding to the Y polarization measurements.

A computer-implemented method of generating an electromagnetic field (EMF) correction boundary layer (BL) model corresponding to a mask, comprising using a computer to perform a method, the method including:

• (a) determining asymmetry factor data from measurements of line widths of photoresist patterns, the photoresist patterns corresponding to images cast by a plurality of gratings at a plurality of different defocus distances, the gratings being representative of features of a mask;
• and
• (b) determining boundary layer parameters of an EMF correction BL model corresponding to the mask by fitting to the asymmetry factor data.