Rigorous simulation study of mask gratings at conical illumination

Abstract

For immersion technology the mask is illuminated under large angles and the features sizes are approaching the illuminating wavelength. At such operating conditions, several publications have shown rigorous diffraction effects having a noticeable effect on the aerial image. For the Kirchhoff assumption, which is commonly employed in lithography simulation, the mask is assumed to be an infinity thin transparency. This assumption implies the diffracted spectrum to be independent of the incident illumination angle and no coupling between polarization states occurs. This work is a fundamental study to deepen the understanding of rigorous off-axis effects for current and future mask technologies. This paper will show simulation studies for standard attenuated-and alternating mask gratings, which look at the diffracted spectrum of a mask grating with respect to polarization orientation and off-axis angle of the illuminating wave.

3D simulations of electromagnetic fields in nanostructures using the time-harmonic finite-element method

“…Through internal or external post-processes, PSfrag replacements (a) (b) (c) the quantities of interest can be derived from the field. E.g., the complex amplitudes of propagating modes are attained by Fourier transformation, an aerial image is calculated, 3 or the field distribution is exported to graphics format for visualisation and analysis.…”

“…E.g., the complex amplitudes of propagating modes are attained by Fourier transformation, an aerial image is calculated, 3 or the field distribution is exported to graphics format for visualisation and analysis.…”

“…This solver has been successfully applied to a wide range of 3D electromagnetic field computations including microlithography, [1][2][3] left-handed metamaterials in the optical regime, 4, 5 photonic crystals, and nearfield-microscopy. 7 The solver has also been used for pattern reconstruction in EUV scatterometry, 8,9 and it has been benchmarked to other methods in typical DUV lithography 1, 2 and other 6, 10 projects.…”

EMF simulations of isolated and periodic 3D photomask patterns

“…1,2 We address 3D simulation tasks occuring in microlithography by using the frequency-domain FEM solver JCMsuite. This solver has been successfully applied to a wide range of 3D electromagnetic field computations including microlithography, [1][2][3][4] left-handed metamaterials in the optical regime, 5 and photonic crystals. 6 The solver has also been used for pattern reconstruction in EUV scatterometry, 7,8 and it has been benchmarked to other methods in typical DUV lithography projects.…”