Fabrication of nickel stamp with improved sidewall roughness for optical devices
We proposed the simple and attractive fabrication method of nickel stamp with improved sidewall roughness for polymeric optical devices. For this, the imprinted optical devices patterns under optimum imprinting conditions were annealed to improve the sidewall roughness generated by the DRIE process in the silicon stamp fabrication. The annealed sidewall roughness is reduced to 24.6nm, nearly decreasing by 76% compared with the result before the annealing. Then, low cost and durable nickel stamp with improved sidewall roughness was fabricated by the annealed polymeric patterns being used as original master for electroforming process. And, we verified the superiority of the improved nickel stamp by comparing the optical propagation losses for optical waveguides to be fabricated, respectively, using the nickel stamp and original silicon stamp. The optical waveguides fabricated by the imprint lithography using the improved nickel stamp was demonstrated that their optical losses were reduced as 0.21dB/cm, which was less than the propagation loss for polymeric waveguides using the conventional original silicon stamp. This result could show the effectiveness of the fabricated nickel stamp with improved sidewall roughness. Furthermore, we were able to successfully fabricate a polymeric 18 beam splitter device using the improved nickel stamp. And, the insertion loss for eight channels obtained to be from 10.02dB to 10.91dB.
nickel stamp sidewall roughness optical devices imprint lithography sub-tg annealing