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12 May 2005 Polarized light for resolution enhancement at 70 nm and beyond
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We have investigated the impact of light polarization on the imaging performance of a high NA 193nm wafer scanner. This system allows the usage of well linear polarized light for imaging at several illumination modes. The printing performance of critical DRAM features have been investigated for various mask types like attenuated, chrome-less and alternating PSM using polarized and depolarized light. Moreover various illumination schemes such as circular, cross-pole and dipole illumination have been tested for different light polarization settings. An improvement of the resolution and the process window, and a reduction of the mask error enhancement factor compared to depolarized light have been obtained using appropriately chosen linear polarization. The influence of light polarization on the proximity behavior has been studied. Under investigation was specifically the proximity behavior change for mask features with attached sub-resolution assist features. Experimental data of the influence of the polarization on the intra-field CD uniformity of densely packed features of critical DRAM layers are presented. Based on the obtained measurement data the CD control improvement potential has been analyzed. Our experimental and simulation results verify that light polarization has resolution enhancing potential already for features of the 70nm node and - of course - beyond.
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Rainer Pforr, Mario Hennig, Max Hoepfl, Tomoyuki Matsuyama, Winfried Meier, and Hisashi Nishinaga "Polarized light for resolution enhancement at 70 nm and beyond", Proc. SPIE 5754, Optical Microlithography XVIII, (12 May 2005);

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