20 May 2004 Development of phase shift masks for extreme ultraviolet lithography and optical evaluation of phase shift materials
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Phase Shift Masks (PSM) for Extreme Ultraviolet Lithography (EUVL) have the potential for extending the lithographic capability of EUVL beyond the 32-nm node. The concept of EUV PSM structures can be implemented either by adding absorber structures on top of the Mo/Si multilayers (additive approach) or by partial etching into the multilayers (subtractive approach). Among many technical challenges, evaluating optical constants of absorber materials is the most important issue particularly for PSM by the additive approach (PSM-ADD), while the etch stop capability and the etch selectivity with vertical sidewall profile are the main technical challenges for PSM fabricated by the subtractive method (PSM-SUB). For fast turn around of PSM development, the indirect optical constant evaluation through material analysis is a useful metrology technique. The optical constant of TaSiN extracted from Rutherford Backscattering Spectroscopy (RBS) data agrees well with that obtained from the direct measurement by transmission interferometric technique. For PSM-SUB, the concept of embedding B4C and NiFe etch stop layer (ESL) is verified by measuring reflectivity of the ESL embedded substrates and demonstrating good etch stop capability.
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Sang-In Han, Sang-In Han, Eric Weisbrod, Eric Weisbrod, James R. Wasson, James R. Wasson, Rich Gregory, Rich Gregory, Qianghua Xie, Qianghua Xie, Pawitter J. S. Mangat, Pawitter J. S. Mangat, Scott D. Hector, Scott D. Hector, William J. Dauksher, William J. Dauksher, Kristine M. Rosfjord, Kristine M. Rosfjord, "Development of phase shift masks for extreme ultraviolet lithography and optical evaluation of phase shift materials", Proc. SPIE 5374, Emerging Lithographic Technologies VIII, (20 May 2004); doi: 10.1117/12.535503; https://doi.org/10.1117/12.535503


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