Enhancing nanolithography fidelity through near-field optical proximity correction

(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.
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.
Physical understanding of the near-field OPE in plasmonic lithography
Physical understanding of the near-field OPE in plasmonic lithography. (ImageƖ UCAS)
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.
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.
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.
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.
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.
Source: Chinese Academy of Sciences (Note: Content may be edited for style and length)
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