Patent ID: 7685557

Claim:
A method for creating a mask, comprising: receiving a specified target transmittance (T S ) of a substrate with respect to a first radiation configured to be propagated from a radiation source and transmitted through the mask with spatial selectivity in accordance with a spatially varying transmissivity (T M ) of the mask with respect to the first radiation; and establishing the mask, wherein said establishing the mask is selected from the group consisting of forming the mask and both designing and forming the mask, and wherein said establishing the mask is subject to: with the mask disposed between the radiation source and a surface portion of a top surface of the substrate, the first radiation after having passed through the mask is denoted as a second radiation that is transmitted into the surface portion of the top surface of the substrate in accordance with a spatially varying reflectance (R) of the surface portion with respect to the second radiation, wherein T M *(1−R) is about equal to T S .