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Journal of Micro/Nanolithography, MEMS, and MOEMS

Mask-induced polarization effects at high numerical aperture
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Paper Abstract

Degradation in image contrast becomes a concern at higher numerical apertures (NAs) due to mask-induced polarization effects. We study how different photomask materials (binary and attenuated phase shift), feature sizes and shapes, pitch values, duty ratios (line to space), and wavelengths effect the polarization of transmitted radiation. Rigorous coupled-wave analysis (RCWA) is used to simulate the polarization of radiation by the photomask. The results show that higher NA leads to greater polarization effects in all cases. Off-axis illumination increases polarization in one of the first orders, decreasing it in the other. Nonvertical sidewall angles and rounded corners can also impact polarization, but the wavelength of incident radiation has no effect on polarization effects at the same NA values. In general, materials with higher refractive indices and lower extinction coefficients tend to pass more of the TM polarization state, whereas materials with lower refractive indices and a relatively wider range of extinction coefficients pass more TE polarized radiation. These properties can provide new design considerations for the development of next-generation masking materials.

Paper Details

Date Published: 1 July 2005
PDF: 8 pages
J. Micro/Nanolith. MEMS MOEMS 4(3) 031107 doi: 10.1117/1.2037507
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 4, Issue 3
Show Author Affiliations
Andrew Estroff, IMEC (Belgium)
Yongfa Fan, Rochester Institute of Technology (United States)
Anatoly Bourov, Rochester Institute of Technology (United States)
Bruce William Smith, Rochester Institute of Technology (United States)

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