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Proceedings Paper

Deposition of durable wideband silver mirror coatings using long-throw low-pressure DC-pulsed magnetron sputtering
Author(s): Jesse D. Wolfe; David M. Sanders; Steve Bryan; Norman L. Thomas
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Paper Abstract

Sputter deposition at long-throw distances (15-30 in.) and low pressures (<1 mTorr) were developed mainly for the semiconductor industry to deposit metals and dielectrics into trenches or vias on silicon and gallium arsenide wafers. Scientists found that sputter depositions performed at pressures below 1 mTorr (0.13 Pa) results in a virtually collision-free trajectory of the sputtered atoms from the target to the substrate. If the throw distance (source to substrate) is increased at these low pressures, the activated (ionized) gas and target atoms maintain their energy. We used this methodology along with dc-pulsed sputtering to deliver additional energy at the substrate. This allowed us to coat large optics (>21-in. diameter) in a standard box coater using smaller-diameter sputter cathodes. This paper will discuss the process used to successfully coat a 22-in.-diameter optic for the Keck Telescope in Hawaii with a new Wide-Band Durable Silver Mirror. The process uses smaller-diameter sputter cathodes in a 4-ft.-x-4-ft.-x-5-ft. box coater. We will also discuss how the process can be scaled to 36-in. or larger optics for use on terrestrial or space-based platforms.

Paper Details

Date Published: 30 January 2003
PDF: 9 pages
Proc. SPIE 4842, Specialized Optical Developments in Astronomy, (30 January 2003); doi: 10.1117/12.458075
Show Author Affiliations
Jesse D. Wolfe, Lawrence Livermore National Lab. (United States)
David M. Sanders, Lawrence Livermore National Lab. (United States)
Steve Bryan, Lawrence Livermore National Lab. (United States)
Norman L. Thomas, Lawrence Livermore National Lab. (United States)


Published in SPIE Proceedings Vol. 4842:
Specialized Optical Developments in Astronomy
Eli Atad-Ettedgui; Sandro D'Odorico, Editor(s)

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