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21 March 2006 Applicability of alternating phase shifting masks using polarized light
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The use of Alternating Phase Shifting Masks (APSM) for sub 50nm half pitch pattern using 193nm lithography was evaluated. Results show that polarized illumination may be necessary for APSM to compete with Half-Tone Phase-Shifting Masks (HTPSM) when printing sub 50nm features. The low sigma illumination conditions required for APSM constraints the choice of a possible polarized illuminator to the TE polarized option therefore limiting the patterns to be oriented in one direction. Topography effects imply the use of polarization-dependant balancing of APSM which should not be a show-stopper as long as it is properly handled at the time the mask is manufactured. Due to topography effects, the MEEF is increased if compared to thin mask approximation but the relative numbers remain manageable. The sensitivity of CD errors with respect to polarization errors of the source is comparable to HTPSM masks. The induced displacement due to polarization errors is small compared to the CD variation of the dark line.
© (2006) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Karsten Bubke, Martin Sczyrba, and Christophe Pierrat "Applicability of alternating phase shifting masks using polarized light", Proc. SPIE 6154, Optical Microlithography XIX, 615449 (21 March 2006);

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