&lt;title&gt;Power spectral density specifications for high-power laser systems&lt;/title&gt;

Lawson, Janice K.; Aikens, David M.; English, R. Edward; Wolfe, C. Robert

doi:10.1117/12.246761

Cited by 40 publications

(19 citation statements)

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“…In the PSD analysis, the 2D PSD (2D-PSD) function P(k x , k y ) at time t is calculated from the 2D discrete Fourier transform (2D-DFT) of the 2D surface height or depth distribution z(m, n) in the (x, y) coordinates [89][90][91][92] …”

Section: Power Spectral Density Analysismentioning

confidence: 99%

Surface roughening and rippling during plasma etching of silicon: Numerical investigations and a comparison with experiments

Tsuda¹,

Nakazaki²,

Takao³

et al. 2014

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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Surface loss rates of H and Cl radicals in an inductively coupled plasma etcher derived from time-resolved electron density and optical emission measurementsModeling of fluorine-based high-density plasma etching of anisotropic silicon trenches with oxygen sidewall passivation Atomic-or nanometer-scale surface roughening and rippling during Si etching in high-density Cl 2 and Cl 2 /O 2 plasmas have been investigated by developing a three-dimensional atomic-scale cellular model (ASCeM-3D), which is a 3D Monte Carlo-based simulation model for plasma-surface interactions and the feature profile evolution during plasma etching. The model took into account the behavior of Cl þ ions, Cl and O neutrals, and etch products and byproducts of SiCl x and SiCl x O y in microstructures and on feature surfaces therein. The surface chemistry and kinetics included surface chlorination, chemical etching, ion-enhanced etching, sputtering, surface oxidation, redeposition of etch products desorbed from feature surfaces being etched, and deposition of etch byproducts coming from the plasma. The model also took into account the ion reflection or scattering from feature surfaces on incidence and/or the ion penetration into substrates, along with geometrical shadowing of the feature and surface reemission of neutrals. The simulation domain was taken to consist of small cubic cells of atomic size, and the evolving interfaces were represented by removing Si atoms from and/or allocating them to the cells concerned. Calculations were performed for square substrates 50 nm on a side by varying the ion incidence angle onto substrate surfaces, typically with an incoming ion energy, ion flux, and neutral reactant-to-ion flux ratio of E i ¼ 100 eV, C i 0 ¼ 1.0 Â 10 16 cm À2 s À1 , and C n 0 /C i 0 ¼ 100. Numerical results showed that nanoscale roughened surface features evolve with time during etching, depending markedly on ion incidence angle; in effect, at h i ¼ 0 or normal incidence, concavo-convex features are formed randomly on surfaces. On the other hand, at increased h i ¼ 45 or oblique incidence, ripple structures with a wavelength of the order of 15 nm are formed on surfaces perpendicularly to the direction of ion incidence; in contrast, at further increased h i ! 75 or grazing incidence, small ripples or slitlike grooves with a wavelength of <5 nm are formed on surfaces parallel to the direction of ion incidence. Such surface roughening and rippling in response to ion incidence angle were also found to depend significantly on ion energy and incoming fluxes of neutral reactants, oxygen, and etch byproducts. Two-dimensional power spectral density analysis of the roughened feature surfaces simulated was employed in some cases to further characterize the lateral as well as vertical extent of the roughness. The authors discuss possible mechanisms responsible for the formation and evolution of the surface roughness and ripples during plasma etching, including stochastic roughening, local micromasking, and effects of ion reflection, surface temp...

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Section: Power Spectral Density Analysismentioning

confidence: 99%

Surface roughening and rippling during plasma etching of silicon: Numerical investigations and a comparison with experiments

Tsuda¹,

Nakazaki²,

Takao³

et al. 2014

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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“…Finishing effects of concern for the outer region of the focal spot are high-frequency figure errors, usually associated with polishing, that have characteristic scale lengths less than -33 mm. The appropriate specification in this regime is the power spectral density of the transmitted wavefront, or PSD [16]. In the central core of the focal spot, corresponding to divergence angles less than -30 urad, the finishing effects of importance are the longerwavelength figure errors, for which the appropriate specification is the RMS gradient of the transmitted wavefront [17].…”

Section: Discussionmentioning

confidence: 99%

Wavefront and divergence of the Beamlet prototype laser

et al. 1999

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“…The STF of the system can then be calculated according to Eq. (6). With the STF of the system thus obtained, its influence on the measured PSD can be removed using the following formula:…”

Section: Data Processingmentioning

confidence: 99%

“…Traditionally, simple statistical measurements such as Zernike polynomials, peak-to-valley wavefront error and root mean square (RMS) roughness are used to obtain an initial quantitative description of the surfaces [3][4][5][6]. These measurements are based on height information and, for certain types of surfaces, can serve as a good description of their roughness.…”

Section: Introductionmentioning

confidence: 99%

Power spectral density measurement for large aspheric surfaces

Chen

Yao

et al. 2008

Front. Optoelectron. China

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To ensure the safe and normal operation of the whole optical system, it is important to test and evaluate the quality of optical components. The article explores the advantages and disadvantages of general parameters used in aspheric surface testing, the composition of the system, the principle of operation and the design of related power spectral density (PSD) software used in testing large aspheric surfaces with Shack-Hartmann and phase shifting interferometer. The results indicate that PSD can give the spatial frequency distribution of the wavefront aberration when large aperture phase shifting interferometer is used as an instrument to test the wavefront, and this can also be applied as an evaluation standard in testing the quality of optical components. In addition, this paper describes the test results of optical components in the size of 64 mm 6 64 mm.

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<title>Power spectral density specifications for high-power laser systems</title>

Cited by 40 publications

References 1 publication

Surface roughening and rippling during plasma etching of silicon: Numerical investigations and a comparison with experiments

Surface roughening and rippling during plasma etching of silicon: Numerical investigations and a comparison with experiments

Wavefront and divergence of the Beamlet prototype laser

Power spectral density measurement for large aspheric surfaces

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