| Apr 26, 2023 |
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(Nanowerk News) Led by Prof. Wei Yayi, a team of researchers from the University of Chinese Academy of Sciences (UCAS) has achieved a significant breakthrough in enhancing the final pattern fidelity in near-field nanolithography. Their findings offer insights into the near-field diffraction limits of an evanescent-field-based patterning system.
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The study, published in Microsystems & Nanoengineering (“Enhancement of pattern quality in maskless plasmonic lithography via spatial loss modulation”), is the first to explore the physical origin of the near-field optical proximity effect (OPE). Theoretical calculations and simulations suggest that the rapid loss of high-k information due to the evanescent field is a primary optical contributor to the near-field OPE.
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| Physical understanding of the near-field OPE in plasmonic lithography. (ImageÖ UCAS)
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As feature sizes shrink, pattern profiles created by near-field lithography exhibit poor quality due to the near-field OPE, falling short of the minimum requirements for nanofabrication. To achieve the highest possible pattern resolution and fidelity in plasmonic lithography, it is crucial to minimize the near-field OPE.
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The researchers delved into the physical principles underlying the near-field OPE in maskless plasmonic lithography and proposed a near-field optical proximity correction (OPC) technique using spatial modulation of nanopatterns to enhance the final pattern quality.
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Accurate exposure is vital for precise OPC, so the team conducted numerical calculations to estimate the point spread function and to analyze the near-field enhancement effect and size-dependence of the plasmonic near-field quantitatively.
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Moreover, they introduced an analytical formula to quantitatively examine the impact of the rapidly decaying feature of the evanescent field on the near-field OPE and the theoretical limit of pattern fidelity.
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Considering the characteristics of the near-field OPE in plasmonic lithography, the researchers developed a swift and effective method to correct the evanescent-field-induced high-k information loss by compensating the exposure dose in advance in the exposure dose map. Simulation results demonstrated a substantial improvement in the final pattern fidelity.
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