a) defining a target pattern for a structure imaged on a substrate by an exposure tool including the lithographic reflection mask to reflect a radiation, the target pattern comprising a range of target critical dimension values;

b) providing a predefined combination of a plurality of absorber stack parameters, wherein one or more of the absorber stack parameters are constants and one or more of the absorber stack parameters are variables;

c) defining a plurality of absorber stack geometries according to the absorber stack geometry definition by providing a plurality of different values for the one or more variables;

d) for each absorber stack geometry:

i) simulating aerial images of the structure imaged on the substrate for a predetermined range of first values;

ii) evaluating each aerial image by applying a predetermined range of second values to determine corresponding critical dimension values of the structure imaged on the substrate; and

iii) comparing the determined critical dimension values of the structure imaged on the substrate with the range of target critical dimension values of the target pattern to determine a process window, wherein the size of the process window is defined by the first and second values that correspond to the target critical dimension values;

whereby a respective process window is determined for each absorber stack geometry; and

e) comparing the respective sizes of the respective determined process windows to identify a process window having a maximum process window size, thereby identifying the respective absorber stack geometry corresponding to the identified process window.