Researchers use spatial modulation to improve near-field optical proximity correction.

Scientists led by Prof. Wei Yayi from the College of Chinese Foundation of Sciences (UCAS) have further developed the last example of loyalty in close field nanolithography, a leap forward in understanding the close field diffraction cutoff of a transient field-based design framework.

The theoretical calculations and simulations indicate that the evanescent-field-induced rapid loss of high-k information is one of the main optical contributors to the near-field optical proximity effect (OPE). The findings, which were published in Microsystems & Nanoengineering, are the first to investigate the physical origin of the near-field OPE.

Due to the near-field OPE, the pattern profile produced by near-field lithography exhibits very poor pattern quality as the feature size is continuously scaled down, far below the minimum requirement for nanofabrication. In order to get the best pattern resolution and fidelity from the plasmonic lithography process, it is necessary to reduce the near-field OPE.

The physical concepts of near-field optical proximity correction (OPC) in maskless plasmonic lithography were the subject of this study, and a near-field optical proximity correction (OPC) technique based on the spatial modulation of nanopatterns was proposed as a means of improving the quality of the final pattern.

Schematic of the maskless plasmonic lithography framework with a filtering plasmonic tie nanoaperture. Credit: Since UCAS

Precise OPC necessitates precise exposure, numerical calculations were carried out to estimate the point spread function and quantitatively analyze the effect of near-field enhancement and the size-dependent plasmonic near-field.

In addition, the theoretical limit of pattern fidelity and the effect of the rapidly decaying feature of the evanescent field on the near-field OPE were quantitatively analyzed using a proposed analytical formula.

A quick and efficient method for correcting the evanescent-field-induced high-k information loss by exposure dose compensation in advance in the exposure dose map was carried out in light of the characteristics of the near-field OPE in plasmonic lithography. Also, the reenactment results demonstrated the way that the last example of constancy can be extraordinarily moved along.

More information: Dandan Han et al, Enhancement of pattern quality in maskless plasmonic lithography via spatial loss modulation, Microsystems & Nanoengineering (2023). DOI: 10.1038/s41378-023-00512-4

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