&lt;title&gt;Achieving desired thickness gradients on flat and curved substrates&lt;/title&gt;

Broadway, David M.; Platonov, Yuriy Ya.; Gómez, Luis Alfonso Escudero

doi:10.1117/12.363643

Cited by 17 publications

(19 citation statements)

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“…A mathematical model considering the geometry of the sputter tool was developed to predict the thickness distribution of films, similarly as presented in earlier literature. [30][31][32][33]38,42,43 To determine the thickness distribution inherent to the sputter tool geometry, the flat substrate case was considered first. Sputtering parameters such as temperature, power, target chemistry, chamber pressure, and gas species were kept consistent throughout the study and were not considered in the model.…”

Section: Geometric Film Thickness Model For Flat Substratesmentioning

confidence: 99%

“…[26][27][28][29] Sputtered film thickness distributions and microstructures are influenced by sputtering parameters such as the deposition chamber geometry, [30][31][32][33] substrate rotation, [34][35][36] configuration of the magnetron, [37][38][39] and the use of collimators, shadow masks, or differential deposition. [40][41][42][43] Controlling thin film thickness uniformity and microstructure becomes more complicated when depositing onto curved substrates as the ROC of the substrate and the angle of the deposition also play a role. [43][44][45][46][47][48] The use of peaks are labeled with pseudocubic notation for the perovskite.…”

Section: Introductionmentioning

confidence: 99%

“…[40][41][42][43] Controlling thin film thickness uniformity and microstructure becomes more complicated when depositing onto curved substrates as the ROC of the substrate and the angle of the deposition also play a role. [43][44][45][46][47][48] The use of peaks are labeled with pseudocubic notation for the perovskite. In addition, the (111) Pt peak is labeled, and the * symbol indicates instrument-related x-ray peaks.…”

Section: Introductionmentioning

confidence: 99%

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Thickness distribution of sputtered films on curved substrates for adjustable x-ray optics

Bishop

Walker

DeRoo

et al. 2019

J. Astron. Telesc. Instrum. Syst.

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McKinstry, "Thickness distribution of sputtered films on curved substrates for adjustable x-ray optics," J.Abstract. Piezoelectric adjustable x-ray optics use magnetron sputtered thin film coatings on both sides of a thin curved glass substrate. To produce an optic suitable for a mission requiring high-angular resolution like "Lynx," the integrated stresses (stress × thickness) of films on both sides of the optic must be approximately equal. Thus, understanding how sputtered film thickness distributions change for convex and concave curved substrates is necessary. To address this, thickness distributions of piezoelectric Pb 0.995 ðZr 0.52 Ti 0.48 Þ 0.99 Nb 0.01 O 3 films are studied on flat, convex, and concave cylindrical substrates with a 220-mm radius of curvature. A mathematical model of the film thickness distribution is derived based on the geometric properties of the sputter tool and the substrate, and film thicknesses deposited with a commercially available sputtering tool are measured with spectroscopic ellipsometry. Experiment and modeled results for flat and convex curved substrates demonstrate good agreement, with average relative thickness distribution difference of 0.19% and −0.10% respectively, and a higher average difference of 1.4% for concave substrates. The calculated relative thickness distributions are applied to the convex and concave sides of a finite-element analysis (FEA) model of an adjustable x-ray optic prototype. The FEA model shows that, left uncorrected, the relative film thickness variation will yield an optic with an optical performance of 2.6 arc sec half power diameter (HPD) at 1 keV. However, the mirror figure can be corrected to diffraction-limited performance (0.3 arc sec HPD) using the piezoelectric adjusters, suggesting that the tolerances for applying a balanced integrated stress on both sides of a mirror are alleviated for adjustable x-ray optics as compared to traditional static x-ray mirrors. Furthermore, the piezoelectric adjusters will also allow changes in mirror figure over the telescope lifetime due to drift in the stress states of the x-ray surfaces to be corrected on orbit.

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Section: Geometric Film Thickness Model For Flat Substratesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thickness distribution of sputtered films on curved substrates for adjustable x-ray optics

Bishop

Walker

DeRoo

et al. 2019

J. Astron. Telesc. Instrum. Syst.

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“…Coating geomtries have recently been described for this type of cylindrical mirror segments which can reduce this variation to the 1% level. 19 …”

Section: Uniformity Measurementsmentioning

confidence: 99%

<title>Hard x-ray characterization of a HEFT single-reflection prototype</title>

et al. 2000

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We have measured the hard X-ray reflectivity and imaging performance from depth graded W/Si multilayer coated mirror segments mounted in a single reflection cylindrical prototype for the hard X-ray telescopes to be flown on the High Energy Focusing Telescope(HEFT) balloon mission. Data have been obtained in the energy range from 18 -170 keV at the European Synchrotron Radiation Facility and at the Danish Space Research Institute at 8 keV. The modeling of the reflectivity data demonstrate that the multilayer structure can be well described by the intended power law distribution of the bilayer thicknesses optimized for the telescope performance and we find that all the data is consistent with an interfacial width of 4.5 A. We have also demonstrated that the required 5% uniformity of the coatings is obtained over the mirror surface and we have shown that it is feasible to use similar W/Si coatings for much higher energies than the nominal energy range of HEFT leading the way for designing Gamma-ray telescopes for future astronomical applications. Finally we have demonstrated 35 arcsecond Half Power Diameter imaging performance of the one bounce prototype throughout the energy range of the HEFT telescopes.

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“…In this study, a simple and facile method for designing shadow masks was developed at the IPOE to deposit uniform multilayers on curved spherical substrates through DC magnetron sputtering with PRS, which did not require consideration of the ejection characteristics of different sputtering materials [30,31]. The multilayer structure, utilized DC magnetron sputtering system, thickness measurement method, and mask design are described in detail in the subsequent sections.…”

Section: Introductionmentioning

confidence: 99%

Improving Thickness Uniformity of Mo/Si Multilayers on Curved Spherical Substrates by a Masking Technique

Zhang

Yao

et al. 2019

Coatings

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In this work, a masking technique was used to improve the thickness uniformity of a Mo/Si multilayer deposited on a curved spherical mirror by direct current (DC) magnetron sputtering with planetary rotation stages. The clear aperture of the mirror was 125 mm with a radius of curvature equal to 143.82 mm. Two different shadow masks were prepared; one was flat and the other was oblique. When using the flat mask, the non-uniformity considerably increased owing to the relatively large gap between the mask and substrate. The deviation between the designed and measured layer thickness and non-uniformity gradually reduced with a smaller gap. The second mask was designed with an oblique profile. Using the oblique mask, the deviation from multilayer thickness uniformity was substantially reduced to a magnitude below 0.8% on the curved spherical substrate over the clear aperture of 125 mm. Multilayers still achieved a smooth growth when deposited with obliquely incident particles. The facile masking technique proposed in this study can be used for depositing uniform coatings on curved spherical substrates with large numerical apertures for high-resolution microscopes, telescopes, and other related optical systems.

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<title>Achieving desired thickness gradients on flat and curved substrates</title>

Cited by 17 publications

References 0 publications

Thickness distribution of sputtered films on curved substrates for adjustable x-ray optics

Thickness distribution of sputtered films on curved substrates for adjustable x-ray optics

<title>Hard x-ray characterization of a HEFT single-reflection prototype</title>

Improving Thickness Uniformity of Mo/Si Multilayers on Curved Spherical Substrates by a Masking Technique

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