A multi-objective optimization flow is developed to identify balanced compact optical proximity correction (OPC) models with ideal calibration accuracy, runtime performance and prediction accuracy. We demonstrate a model selection process based on Pareto front optimization to meet multiple modeling requirements in a single optimization step. A genetic search algorithm determines the final population that offers the best trade-off in set model properties. As a demonstration, we cooptimize calibration accuracy, verification accuracy and term count in a mode developed for hot spot prediction for a line and space memory layer. The optimization determines the minimum number of model terms to meet the off-nominal dose and focus patterning accuracy requirements in verification. Multi-objective optimization provides better verification process window condition (PWC) accuracy because of the multi-objective trade-off built into the genetic algorithm (GA). The optimizer also provides better calibration accuracy (Rms Weighted) than compact models with a fixed configuration because model composition is optimized during GA search. The resulting champion model is 30% more predictive and 5% faster in simulation using this approach. Results for a negative tone develop hole layer with a model complexity of up to 44 terms are also analyzed based on nominal only measurement data. We further show the models selected by multi-objective optimization have a lesser tendency to over-fit the calibration data. The methodology can be applied to streamline complex models for optimum performance and target error rate. In many cases, for smaller data sets, we show that simplified models provide improved verification accuracy within metrology error limits.
Beyond the 40nm technology node, layout weak points and hotspot types increase dramatically. Many hotspots can be detected by OPC simulation. However, in advanced nodes, OPC simulation suffers from a long turn-around-time (TAT) and is challenged to handle the additional design complexity. Therefore, in order to speed up the process and OPC development, an efficient OPC hotspot detection method is required. This paper presents a flow using Pegasus Computational Pattern Analytics (CPA) technology from Cadence to extract a comprehensive set of patterns to build a pattern bank from a layout source. We can then compare two or more different banks (diffing) to find new patterns which have not been processed before. OPC engineers can analyze these new patterns to check for any OPC issues instead of simulating a full chip. This flow provides a much higher efficiency and better performance while allowing the storage of pattern banks over time to build history and yield experience. Over time, each new layout introduced for OPC can be processed faster because more patterns have been added to the banks and less simulation time is needed.
Critical dimension analysis of cross-section image with delicate accuracy has become important demand for semiconductor manufacturing. In traditional analytic method, manual measurements always accompany large deviation and lower measured efficiency. Therefore, a robust and reliable analysis method is most essential objective to obtain accurate dimensions from PFA results. In this work, we demonstrate an intelligent image analysis method which is combined Mask Region based Convolution Neural Networks (Mask r-CNN) and image processing technique. Compared with manual measurement, intelligent image analysis method can achieve significant improvement on measured results in reproducibility, repeatability, and efficiency. This intelligent image analysis will provide novel applications in CD measurement, wafer defect analysis, and focus-exposure process window judgment.
The functionalities of traditional optical component are mainly based on the phase accumulation through the propagation length, leading to a bulky optical component such as converging lens and waveplate. Metasurfaces composed of planar structures with artificial design have attracted a huge number of interests due to their ability on controlling the electromagnetic phase as well as amplitude at a subwavelength scale. The feasible applications based on metasurfaces include nonlinear dynamics, light beam shaping, quantum interference etc. Beside those promising characteristics, people now intend to discover the field of meta-devices, where we can attain optical properties and functionalities through changing the feature characteristics of metasurfaces in demand. They therefore pave a potential way for the development of flat optical devices and integrated optoelectronic systems and toward the far-reaching applications which are impossible previously. In this talk, four research topics for photonic applications with metasurfaces and meta-devices will be performed and discussed: high efficiency anomalous beam deflector, highly dimensional holographic imaging, versatile polarization control and metadevices with active property.
Natural toroidal molecules, such as biomolecules and proteins, possess toroidal dipole moments that are hard to be
detected, which leads to extensive studies of artificial toroidal materials. Recently, toroidal metamaterials have been
widely investigated to enhance toroidal dipole moments while the other multipoles are eliminated due to the spacial
symmetry. In this talk, we will show several cases on the plasmonic toroidal excitation by engineering the near-field
coupling between metamaterials, including their promising applications. In addition, a novel design for a toroidal
metamaterial with engineering anapole mode will also be discussed.
The toroidal dipole moments of natural molecules are hard to be detected so the artificial toroidal materials made by metamaterial attract more attentions. Metamaterial, the sub-wavelength artificial structures, can modulate reflection or transmission of light. The toroidal metamaterial can not only amplify the toroidal moment but also repress the electric and magnetic dipole so it can be used to study the properties of toroidal dipole moment. However, there are many limitations for the experiments, such as the lateral light is necessary to excite the toroidal response. Most of the toroidal dipole moments oscillate perpendicularly to the substrate, therefore it is difficult to couple it with other dipole moments and could be only excited in the microwave region. In this paper, we design a toroidal metamaterial consisting of dumbbell-shaped aperture and vertical split ring resonator (VSRR) vertically. The toroidal dipole moment of our metamaterial is excited in the optical region. The arrangement of our nanostructures is vertical instead of planar annular arrangement to reduce the size of the unit cell and increase the density of the toroidal dipole moment. Moreover, the direction of toroidal dipole moment is parallel to the substrate which can be used for the study of the coupling effect with other kinds of dipolar moments.
Split-ring resonator (SRR), one kind of building block of metamaterials, attracts wide attentions due to the resonance excitation of electric and magnetic dipolar response. The fundamental plasmonic properties and potential applications in novel three dimensional vertical split-ring resonators (VSRRs) are designed and investigated. The resonant properties arose from the electric and magnetic interactions between the VSRR and light are theoretically and experimentally studied. Tuning the configuration of VSRR unit cells is able to generate various novel coupling phenomena in VSRRs, such as plasmon hybridization and Fano resonance. The magnetic resonance plays a key role in plasmon coupling in VSRRs. The VSRR-based refractive-index sensor is demonstrated. Due to the unique structural configuration, the enhanced plasmon fields localized in VSRR gaps can be lifted off from the dielectric substrate, allowing for the increase of sensing volume and enhancing the sensitivity. We perform a VSRR based metasurface for light manipulation in optical communication frequency. By changing the prong heights, the 2π phase modulation can be achieved in VSRR for the design of metasurface which can be used for high areal density integration of metal nanostructures and optoelectronic devices.
Toroidal dipole moments, the third kind of fundamental dipole moment, have unusual electromagnetic properties
different from the electric and magnetic multipoles. We fabricate a new type of 3D plasmonic toroidal metamaterial by
using mutual coupling between dumbbell-shaped gold apertures with vertical split-ring resonators (VSRRs) at optical
frequency. The radiated power of multipole moments are calculated and analyzed to improve the meta-system is
dominated by the toroidal dipole moment. This result paves a way for practical application on metamaterial based
devices, such as biosensor and lasing spaser.
Split ring resonator (SRR) has attracted wide attentions since the discovery of negative refraction in 2002. Here, we
designed and fabricated vertical SRR (VSRR) arrays and toroidal metamolecule by using double exposure e-beam
lithography with precise alignment technique, and their resonance behaviors are subsequently studied in optical region.
The fundamental resonance properties of VSRR are studied as well as the plasmon coupling in a VSRR dimer structure
by changing the gap distance between SRRs. In addition, we proposed a three-dimensional toroidal structure composed a
VSRR with a dumbbell structure that supported a toroidal resonance under normal incidence with broadband working
frequency. Such toroidal metamaterial confines effectively the electric as well as magnetic energy paving a way for
promising applications in the field of plasmonics, such as integrated 3D plasmonic metamaterials, plasmonic biosensor
and lasing spaser.
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