Rules are derived to obtain specifications on radiance, power, lifetime, and cleanliness of the source for an actinic patterned mask inspection system. We focus on the physical processes and technological aspects governing the requirements of radiation sources for reticle inspection. We discuss differences and similarities to scanner with respect to magnification, system etendue, and image recording. Source radiance requirements are estimated from a perspective of targeted throughput and defect detection sensitivity. The derivations consider the influence of photon shot noise on signal detection and conservation laws of light etendue and radiant flux. We describe the scaling laws for required radiance with targeted sensitivity index, optical contrast, field size, and system throughput. In addition, we address the limits on the required brightness and minimum repetition rate set by mask damage threshold. Finally, system and source cleanliness requirements and criticality of the source availability and lifetime are discussed. The analysis can be applied to other microscopy-based metrology and inspection applications.
Thermal conduction in periodic multilayer composites can be strongly influenced by nonequilibrium electron-phonon scattering for periods shorter than the relevant free paths. Here we argue that two additional mechanisms-quasiballistic phonon transport normal to the metal film and inelastic electron-interface scattering-can also impact conduction in metal/dielectric multilayers with a period below 10 nm. Measurements use the 3ω method with six different bridge widths down to 50 nm to extract the in- and cross-plane effective conductivities of Mo/Si (2.8 nm/4.1 nm) multilayers, yielding 15.4 and 1.2 W/mK, respectively. The cross-plane thermal resistance is lower than can be predicted considering volume and interface scattering but is consistent with a new model built around a film-normal length scale for phonon-electron energy conversion in the metal. We introduce a criterion for the transition from electron to phonon dominated heat conduction in metal films bounded by dielectrics.
Extreme ultraviolet (EUV) lithography requires nanostructured optical components, whose reliability can be influenced by radiation absorption and thermal conduction. Thermal conduction analysis is complicated by sub-continuum electron and phonon transport and the lack of thermal property data. This paper measures and interprets thermal property data, and their evolution due to heating exposure, for Mo/Si EUV mirrors with 6.9 nm period and Mo/Si thickness ratios of 0.4/0.6 and 0.6/0.4. We use time-domain thermoreflectance and the 3ω method to estimate the thermal resistance between the Ru capping layer and the Mo/Si multilayers (RRu-Mo/Si = 1.5 m2 K GW−1), as well as the out-of-plane thermal conductivity (kMo/Si 1.1 W m−1 K−1) and thermal anisotropy (η = 13). This work also reports the impact of annealing on thermal conduction in a co-deposited MoSi2 layer, increasing the thermal conductivity from 1.7 W m−1 K−1 in the amorphous phase to 2.8 W m−1 K−1 in the crystalline phase.
Tantalum Nitride (TaN) films carry high heat fluxes in a variety of applications including diffusion barriers in magnetoresistive random access memory and buffer/absorbers in extreme ultraviolet masks. The thicknesses of these films are usually of the same order as the thermal energy carrier mean free path, which complicates the study of heat conduction. This paper presents thermal (cross-plane) and electrical (in-plane) conductivity measurements on TaN films with thicknesses of 50, 75, and 100 nm. Picosecond thermoreflectance is used to extract the thermal boundary resistance between TaN and Al and the intrinsic thermal conductivity of TaN for temperatures of 300–700 K. The data and the relative importance of boundary resistances, electron-boundary scattering, and electron-defect scattering are interpreted using the electrical and thermal transport data. These data facilitate comparison of the phonon and electron contributions to thermal conduction in TaN.
Reticle quality and the capability to qualify a reticle are key issues for EUV Lithography. We expect current and planned optical inspection systems will provide inspection capability adequate for development and production of 2X HP masks. We illustrate inspection technology extendibility through simulation of 193nm-based inspection of advanced EUV patterned masks. The influence of EUV absorber design for 193nm optical contrast and defect sensitivity will be identified for absorber designs of current interest.
A high-resolution synchrotron x-ray study of oriented, supported, hydrated dilauryl phosphatidylcholine in the lyotropic ${L}_{\ensuremath{\alpha}}$ (smectic-A or ``fluid'') phase shows that thermal fluctuations give rise to algebraic decay of positional order in stacking of the bimolecular lamellae, the so-called ``Landau-Peierls'' state. For planar monocrystalline samples of thickness 10--20 \ensuremath{\mu}m, the exponents derived from intensity profiles are in accord with harmonic theory. When combined with previous measurements of the splay elastic constant K in this lyotropic system, the exponents indicate a bulk compressional elastic constant B=(1.9\ifmmode\pm\else\textpm\fi{}1.0)\ifmmode\times\else\texttimes\fi{}${10}^{8}$ erg/${\mathrm{cm}}^{3}$, consistent in magnitude with values measured in thermotropic liquid crystals. Samples of thickness \ensuremath{\sim}1--2 \ensuremath{\mu}m show anomalous behavior in the wings of the longitudinal intensity profiles, but are not in accord with harmonic theory, suggesting that surface effects partially quench the thermal fluctuations. Grandjean terraces on sample surfaces produce striking refractive effects at low Bragg angles.
The results of a high-resolution, synchrotron x-ray powder diffraction study of lattice constants in the ${P}_{\ensuremath{\beta}\mathcal{'}}$ (``rippled'') phase of lecithin-water multilamellar mixtures are given. The variation with water volume fraction ${\ensuremath{\varphi}}_{w}$ and hydrocarbon chain length ${N}_{c}$ of the modulation wave vector ${Q}_{r}$ suggests that membrane curvature and hydration interactions between membranes play a significant role in the modulation. The dependence of the membrane thickness and area per head group on ${N}_{c}$ indicates that the conformation of hydrocarbon chains is predominantly solidlike. The appearance of significant intensity in higher harmonics of the modulation wave vector rules out simple (e.g., sinusoidal or triangular) membrane density modulations. The results are consistent with a Lifshitz phenomenological model for lamellar phases of interacting membranes proposed by Goldstein and Liebler [Phys. Rev. Lett. 61, 2213 (1988)]. The phase behavior predicted by the model includes a multicritical point called the Lifshitz point where the wavelength of the modulation diverges. The experimental results indicate that this multicritical point lies in the vicinity of ${N}_{c}$=9 and ${\ensuremath{\varphi}}_{w}$=0.18.