A master thesis from Aalborg University
Fabrication of High Aspect Ratio Microstructures using Time Multiplexed Reactive Ion Etching
Author(s)
Term
4. term
Education
Publication year
2015
Submitted on
2015-08-30
Pages
77 pages
Abstract
The main objective of this Master’s thesis has been to fabricate a gradient index lens, based on a theoretical design by Brincker and Karlsen [1]. The fabrication of the gradient index lens utilizes the deep reactive ion etching process called the Bosch process, in an attempt to create high aspect ratio microstructures. A systematic optimization of the Bosch process, utilizing SF6 as an etching gas and C3F8 as a passivation gas in a reactive ion etching system, was carried out. The Bosch process was optimized and structures with vertical sidewalls, and an aspect ratio of 22, was successfully fabricated. The Bosch process showed a high stability and good profile control. Chromium was used a as hard mask and showed a high selectivity. Microtrenching was observed under certain structural conditions and resulted in a non-uniform etch rate. The limiting factor of the aspect ratio was the thickness of the masking material. To achieve an aspect ratio higher than 22, further optimization of the process has to be carried out.
Documents
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