Three-dimensional photolithography simulation

Phase-Shift Photomask Designed by Scalar Diffraction Theory

“…Such square-root behavior of resolution degradation with respect to d g , follows from the Fresnel diffraction theory, valid for near field observation behind the apertures of the mask (2). Considering conventional optical lithography, typical values are k = 1.6, = 0.4 µm, and d g = 25 µm, resulting on a resolution W = 4 µm.…”

“…In the seventies, in order to reduce induced defects due to this physical contact, proximity printing has been a popular lithographic technique for microelectronic fabrication, because of its simplicity and low cost. As the feature size shrinks down toward VLSI, resolution issues prohibited the use of proximity exposure because of the diffraction effect caused by the edges of the geometric features present in the mask (1,2). Although the resolution achieved by proximity printing technique is far larger for VLSI and ULSI microelectronic fabrication, it can be very suitable for MEMS and MOEMS devices, with dimensions that typically range from several micrometers to several millimeters.…”

Benchmark of FEM, waveguide and FDTD algorithms for rigorous mask simulation

“…We have performed a benchmark of the previously described FEM solver JCMharmony and two other advanced methods, which are also commercially available: The Finite-Difference Time-Domain solver SOLID E, 21 and the solver Delight, 8 which relies on a waveguide-method. In this benchmark we have investigated light propagation through a phase mask.…”

“…4 In this contribution, the new FEM solver is benchmarked against an analytical result which is fairly realistic for lithography, and against two competing algorithms commonly applied for the simulation of "thick" phase masks. For the simulation of periodic mask patterns in lithography the most prominent rigorous simulation methods include the finite-difference time domain algorithm (FDTD) 5,6 and the modal methods such as the differential method 7,8 or the closely related rigorous coupled wave analysis (RCWA). 9 The methods differ in the way Maxwell's equations are numerically solved and how the boundary conditions of the interfaces to the unbound regions above and below the mask are established.…”