SU-8 Hydrophilic Modification by Forming Copolymer with Hydrophilic Epoxy Molecule

摘要

In this study, we develop a method to permanently modify SU-8 resist (Microchem, Inc., USA) to be a more hydrophilic material. SU-8 is often used in MEMS for the fabrication of high aspect ratio structures. It's major chemical structure is aromatic ring and epoxy functional part, which result in a large water contact angle after cross-link. To permanently modify SU-8 surface, a copolymer method by employing glycidol in SU-8 resist is proposed. Due to glycidol's similar epoxy structure to SU-8 resist and hydrophilic functional group, SU-8' cross-linker can cross-link this copolymer with SU-8's epoxy molecules to produce hydrophilic resist. Test result demonstrated a 20° contact angle reduction on the modified SU-8 surface. The modified SU-8 surface has lasted at least one week and has been verified to resist the washing by acetone and IPA.