Topography description model for 3D exposure simulation

The problem of accurately describing the topography of a mask arose in x-ray lithography, where the absorber structures have dimensions of several hundred wavelengths and may have topography. However, the application of phase shifting structures and a refinement of the image formation calculation even in optical masks has recently raised the same issue for the case of optical lithography. This paper reports the design and implementation of Topography Description Model (TDM), a rule-based 3D topography generator that allows the user to describe the exposure system, such as a system comprising of mask, gap, resist and wafer. The paper illustrates some applications of TDM to real-world studies, such as studying the effect of absorber side-wall slope on the final image and optimizing XRL masks.