The focusing spot beyond diffraction limit is critical to plasmonic direct-writing lithography. To improve the speed and precision of plasmonic direct-writing lithography, we design a new periodically repeated circular hole/elliptical ring plasmonic structure named as split-focusing structure used for producing two focusing spots under the incidence of linearly polarized plane wave at 633nm wavelength. It consists of SiO2 substrate and coated silver film with holes and slits of different shapes. By designing appropriate structure parameters to excite localized surface plasmon resonance, two split subwavelength spots are produced on the focal plane. Finite-difference time-domain (FDTD) method is used for numerical simulation. The simulation result indicates that the focal length of structure is 36nm and the full width at half maximum (FWHM) of single spot is 50nm. Both split spots can be used for direct writing so the speed of photoetching will be raised. The dual spots are both in circular shape, which is beneficial to improve the pattern precision. The influence of structure parameters on focusing performance is also analyzed to guide the practical fabrication of structure. The split-focusing structure designed in this paper also owns application values in data storage and non-contact sensing.
As the numerical aperture (NA) of the projection objective increases continually and the exposure pattern feature size decreases gradually, the polarization illumination is introduced into the lithography system. Therefore, it is necessary to design a wide field-of-view (FOV) wave plate to eliminate the effect of oblique incident light on the phase delay of the traditional zero order wave plate effectively. The quarter-wave plate with 20° FOV based on birefringent optical crystals has been designed in our laboratory by Dong et al. In order to obtain a wider FOV, we explore a previously reported Ag patch ultrathin quarter-wave plate whose performances were not analyzed by finite-difference time-domain (FDTD) method. In this paper, we mainly investigate three performances of the Ag patch quarter-wave plate consisting of FOV, achromatic band and achromatic band transmission. The simulation results indicate that when phase difference error is controlled at ±2° (1) the range of FOV of the quarter-wave plate is ±29° at 632nm; (2) the achromatic band ranges from 618nm to 658nm at normal incidence; (3) the achromatic band transmission ranges from 11% to 30%. Compared with the traditional wave plate made of birefringent crystals, the achromatic band and transmission is slightly lower but the FOV of this quarter-wave plate is much wider. Thus, this Ag patch nanoscale wide FOV quarter-wave plate can be effectively used in high NA lithography projection exposure systems to reduce the polarization aberration caused by oblique incidence of light.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.