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Proceedings Paper

Process improvements in the production of silicon immersion gratings
Author(s): Cynthia B. Brooks; Benjamin Kidder; Michelle Grigas; Ulf Griesmann; Daniel W. Wilson; Richard E. Muller; Daniel T. Jaffe
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Paper Abstract

We have explored a number of lithographic techniques and improvements to produce the resist lines that then define the grating groove edges of silicon immersion gratings. In addition to our lithographic process using contact printing with photomasks, which is our primary technique for the production of immersion gratings, we explored two alternative fabrication methods, direct-write electron beam and photo-lithography. We have investigated the application of antireflection (AR) coatings during our contact printing lithography method to reduce the effect of Fizeau fringes produced by the contact of the photomask on the photoresist surface. This AR coating reduces the amplitude of the periodic errors by a factor of 1.5. Electron beam (e-beam) patterning allows us to manufacture gratings that can be used in first order, with groove spacing down to 0.5 micrometer or smaller (2,000 grooves/mm), but could require significant e-beam write times of up to one week to pattern a full-sized grating. The University of Texas at Austin silicon diffractive optics group is working with Jet Propulsion Laboratory to develop an alternate e-beam method that employs chromium liftoff to reduce the write time by a factor of 10. We are working with the National Institute of Standards and Technology using laser writing to explore the possibility of creating very high quality gratings without the errors introduced during the contact-printing step. Both e-beam and laser patterning bypass the contact photolithography step and directly write the lines in photoresist on our silicon substrates, but require increased cost, time, and process complexity.

Paper Details

Date Published: 22 July 2016
PDF: 12 pages
Proc. SPIE 9912, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation II, 99123Z (22 July 2016); doi: 10.1117/12.2233388
Show Author Affiliations
Cynthia B. Brooks, The Univ. of Texas at Austin (United States)
Benjamin Kidder, The Univ. of Texas at Austin (United States)
Michelle Grigas, The Univ. of Texas at Austin (United States)
Ulf Griesmann, National Institute of Standards and Technology (United States)
Daniel W. Wilson, Jet Propulsion Lab. (United States)
Richard E. Muller, Jet Propulsion Lab. (United States)
Daniel T. Jaffe, The Univ. of Texas at Austin (United States)


Published in SPIE Proceedings Vol. 9912:
Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation II
Ramón Navarro; James H. Burge, Editor(s)

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