Optoelectronics Letters, Volume. 12, Issue 3, 182(2016)

Thick SU8 microstructures prepared by broadband UV lithography and the applications in MEMS devices

Dong-ling LI*... Zhi-yu WEN, Zheng-guo SHANG and Yin SHE |Show fewer author(s)
Author Affiliations
  • National Key Laboratory of Fundamental Science of Novel Micro/Nano Device and System Technology, Key Laboratory of Optoelectronic Technology and System of the Education Ministry of China, Micro System Reaserch Center, Chongqing University, Chongqing 400030, China
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    Thick SU8 microstructures with high aspect ratio and good side wall quality were fabricated by ultraviolet (UV) lithography, and the processing parameters were comprehensively studied. It proves that the adhesion of SU8 on silicon (Si) substrates is influenced by Si-OH on the surface, and can be improved by the HF treatment. Cracks and delamination are caused by large internal stress during fabrication process, and are significantly influenced by soft bake and post-exposure bake processes. The internal stress is reduced by a low post-exposure bake exposure temperature of 85 °C for 40 min. A three-step soft bake enhances the reflowing of SU8 photoresist, and results in uniform surface and less air bubbles. The vertical side wall is obtained with the optimized exposure dose of 800 mJ/cm2 for the thickness of 160 μm. Using the optimized fabrication process combined with a proper structure design, dense SU8 micro pillars are achieved with the aspect ratio of 10 and the taper angle of 89.86°. Finally, some possible applications of SU8 in micro-electromechanical system (MEMS) device are developed and demonstrated.

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    LI Dong-ling, WEN Zhi-yu, SHANG Zheng-guo, SHE Yin. Thick SU8 microstructures prepared by broadband UV lithography and the applications in MEMS devices[J]. Optoelectronics Letters, 2016, 12(3): 182

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    Paper Information

    Received: Jan. 12, 2016

    Accepted: --

    Published Online: Oct. 12, 2017

    The Author Email: Dong-ling LI (lidongling@cqu.edu.cn)

    DOI:10.1007/s11801-016-6015-4

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