Properties Of Incident Light Research Articles

Polarization effects induced by the bi-layer attenuated phase-shift mask and their impacts on near-field distribution

As ArF projection lithography is approaching 45nm technology node and beyond, polarization effects induced by mask are remarkable. At this mask dimension, traditional Kirchhoff approximation is invalid. Rigorous mask model is needed for accurate evaluation of mask diffraction. In previous works, many researchers are focus on the single grating layer diffraction. In this paper, Lee's formulation based on rigorous coupled wave analysis is applied to simulate the bi-layer grating diffraction in lithography. Then, polarization states as function of mask and incident light properties are evaluated. At last, the impacts on near-field distribution with different polarization state are further investigated. The image quality becomes worse under TE polarization, when Ta thickness becomes 35nm, where the phase effects are effectively reduced. There should be a tradeoff between them.

Simulation of the polarization effects induced by the bilayer absorber alternating phase-shift mask in conical diffraction

Hyper numerical aperture (NA) and off-axis illumination enable extension of ArF lithography for 45 nm technology node and beyond. Also, rigorous electromagnetic field modeling is taken into account for the optical and topographical properties of the mask. A rigorous three-dimensional mask model for bilayer absorber alternating phase shift mask (AltPSM) with the rigorous coupled-wave analysis (RCWA) is established. First, the harmonic waves are expanded based on the least common multiple of the periods in order to model the diffraction of multiple grating layers with different periods. Second, Lalanne’s formulation is used to improve the convergence of RCWA for multiple grating layers in conical diffraction. Third, the enhanced transmittance matrix approach is also extended to conical diffraction to avoid the numerical instability. Given the chromium oxide/chromium AltPSM, the change of polarization state as a function of mask and incident light properties is investigated. When the linewidth is below 30 nm, the mask acts as a transverse magnetic field polarizer, which is not preferred in terms of image quality, so the mask-induced polarization effects must be considered in the hyper NA lithography.

Influence of surface roughness on the polarimetric characteristics of a wire-grid grating polarizer

The influence of surface roughness on the polarimetric performance of a wire-grid polarizer (WGP) is numerically investigated using rigorous coupled-wave analysis over 100 random surface realizations. Surface roughness is modeled with a Gaussian surface, represented by two independent parameters: surface height deviation and correlation length of a profile. The results show that WGP performance can suffer from significant degradation as well as increased deviation with surface roughness, although the extent varies with specific parameters. The influence of roughness was also examined with respect to grating period as a WGP parameter and incident light properties, such as wavelength and angle.

Propagating modes in subwavelength cylindrical holes

We analyze subwavelength cylindrical holes in an optically thick metallic film with the metal described by a plasmonic model. We emphasize that such holes always support propagating modes near the surface plasmon frequency, regardless of how small the holes are. Based on this analysis, we design both single holes and hole arrays in which propagating modes play a dominant role in the transport properties of incident light. These structures exhibit a region of operation that to the best of our knowledge has not been probed yet experimentally, while featuring a high packing density and diffraction-less behavior.

Effect of the plasmonic dispersion relation on the transmission properties of subwavelength cylindrical holes

We analyze subwavelength cylindrical holes in an optically thick metallic film with the metal described by a plasmonic model. We find that the dispersion diagram exhibits three distinct features that have a profound impact on the transmission of incident light through cylindrical holes. First, such holes always support propagating modes near the surface plasmon frequency, regardless of how small the holes are. Second, the fundamental plasmonic mode $({\mathrm{HE}}_{11})$ is located completely below the surface plasmon frequency and gives rise to a passband in the transmission spectrum. Third, when the radius of the holes is small, there exists a stop band, just above the surface plasmon frequency, where a normally incident plane wave does not transmit. Based on the dispersion analysis, we design both a single hole and a hole array in which propagating modes play a dominant role in the transport properties of incident light. These structures exhibit a different region of operation that has not been probed yet experimentally, while featuring a high packing density and diffractionless behavior.

Multi-wavelength optical fiber liquid refractometry based on intensity modulation

A novel approach of development of fiber optic sensor for measurement of refractive index of liquids is presented. This sensor uses two fibers, mirror as reflector and liquid as medium. The light is carried by the illuminating fiber up to modulation zone where the properties of incident light is modulated by modulator. The modulated light is carried by receiving fiber to the detector. The measurement principle is based on reflective intensity modulation. A novel sensing probe is designed with outer ring of fibers acting as illuminating fibers and center fiber acting as read fiber. Using this probe, effect of wavelength on refractive index is studied.

Momentum matrix elements for angle-resolved UV-photoemission from Cu(111): comparison of experimental data and results from one-step calculations

A combined experimental and theoretical analysis of intensities for angle-resolved UV-photoemission out of bulk bands at the Cu(111) surface is presented. We concentrate on the direction and relative magnitude of the momentum matrix elements P fi=〈f| p|i〉 which do not depend on the incident light properties and therefore are very suitable for a comparison of experiment and calculation. Experimental data have been derived from peak intensities measured at fixed electron emission angles θ, but at a large number of light incidence angles ψ i of p-polarized HeI radiation. Theoretical intensities have been extracted from spectra calculated (for the same set of θ, ψ i -combinations) within the fully relativistic formulation of the one-step model. In both cases the determination of P fi relies on the validity of Fresnel's equations, which have been used to calculate the relevant vector potential in the outermost atomic layers of the solid. The results demonstrate that under the experimental conditions of our study the combination of Fresnel's equations and the one-step model gives a qualitatively good description of the observed intensities. Some quantitative discrepancies, however, remain unexplained in this approach.

Polarization effect in scanning near-field optic/atomic-force microscopy (SNOM/AFM)

The polarization effect is reported using a bent optical fiber probe for a scanning near-field optic/atomic-force microscope (SNOM/AFM). We have demonstrated that the SNOM/AFM could be applied to the observation of magnetic domains by imaging polarization contrast in transmission mode. An optical fiber probe with a subwavelength aperture is bent and vibrated vertically as a cantilever for an atomic-force microscope (AFM) for atomic-force regulation. Plane polarized light with an extinction ratio of better than 70 : 1 was emitted by the aperture of the bent probe by controlling the polarization properties of incident light to the probe. By detecting a particular transverse polarization component of light transmitting a sample selected by a polarization analyzer, we obtained clear polarization contrast images of 0.7 μm length bits written on a bismuth-substituted dysprosium-iron-garnet film.