Specific Process Knowledge/Etch/Etching of SU-8
Etching of SU-8
SU-8 can be etched by a oxygen plasma with a small amount of SF6 to remove the antimony present from the photo initiator. Etching of SU-8 has been developed on the ASE and was tested as a mask less reduction of pattern defined by photo lithography. Two processes are available, a high and a low anisotropic etch for use as etching or thinning of structures.
- High anisotropic etch: etch rate ~400nm/min, anisotropy ~0.8
- Low anisotropic etch: etch rate ~180nm/min, anisotropy ~0.3
Recipes in ASE
SU8aniso
The anisotropic SU8aniso etch was design to etch structures in SU-8 with a low roughness of the etched surface, however it has not been tested with any mask material. For a polymeric mask a low selectivity is expected. The etch rate was measured to around 400 nm/min, but will depend on wafer coverage. The surface layer concentration of antimony (Sb) after etch is expected to be below 2%.
| Parameter | SU8aniso etch |
|---|---|
| O2 (sccm) | 99 |
| SF6 (sccm) | 17 |
| Pressure (mTorr) | 40 |
| Coil power (W) | 800 |
| Platen power (W) | 30 |
| Temperature (oC) | 30 |
| Etch rate (nm/min) | ~400 |
| anisotropy | ~0.8 |
===SU8iso