AVS 52nd International Symposium
    Nanometer-Scale Science and Technology Tuesday Sessions
       Session NS-TuP

Paper NS-TuP3
Etch of Sub-Micron High Aspect Ratio Holes in a Bilayer of SU-8/PMMA Resist Stack for Photonic Crystal Devices

Tuesday, November 1, 2005, 4:00 pm, Room Exhibit Hall C&D

Session: Nanometer Scale Science and Technology Poster Session
Presenter: J.H. Sung, Inha University, Korea
Authors: J.H. Sung, Inha University, Korea
K.J. Lim, Inha University, Korea
B.H. O, Inha University, Korea
Y.H. Choe, LG Electronics Institute of Technology, Korea
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Sub-micron hole array in a bilayer of SU-8 for core and poly-methyl-metacrylate (PMMA) for clad have been successfully etched for the fabrication of photonic crystal (PC) structures. In the PC waveguides, the etched holes need to be extended into the cladding layer to ensure the proper optical characteristics. The fabrication started from coating multiple materials on a glass substrate to form a multi-layer of hydrogen silsesquioxane (HSQ)/PMMA/SU-8/PMMA. Using a nano-patterned stamp, PC patterns are imprinted into the top HSQ layer at room temperature. After the pattern transfer by a dry etch in our inductively coupled plasma (ICP) system, Cr sputtering was followed for a lift-off process. The Cr pattern was successfully formed on the top of 1-um-thick SU-8 and 2-um-thick PMMA resist stack. Using this Cr pattern as a hard mask, sub-micron holes are etched also in the ICP etcher. Various gas chemistries are attempted to achieve vertical profiles and a high aspect ratio. The best etch conditions for a PC structure with high aspect ratio and vertical side-wall profile will be discussed.