Microstructuring of 45-μm-deep dual damascene openings in SU-8/Si by UV-assisted thermal imprinting with opaque mold

In this study, we demonstrated a process for fabricating a dual damascene opening in a chemically amplified negative UV photoresist, such as SU-8. The process is based on a UV-assisted thermal-imprinting process, which involved UV pretreatment and thermal imprinting using a Ni mold. After establishing process parameters (e.g., adhesion enhancing, UV pre-treating, thermal imprinting, and etch back conditions) for the given geometry and dimensions of the mold pattern, we could successfully form 25-μm-deep trenches with a 10 μm line-and-space pattern and 45 μm-deep via holes in SU-8/Si samples by UV-assisted thermal imprinting, followed by O₂/CHF₃ reactive ion etching (RIE). Delamination defects could be avoided with the help of adhesion enhancement treatment. The process studied here showed great potential in reducing time and cost compared with the standard photolithographic dual damascene process.