Specific Process Knowledge/Etch/Etching of SU-8: Difference between revisions
| Line 54: | Line 54: | ||
===SU8iso=== | ===SU8iso=== | ||
The SU8iso etch was developed for thinning of lithography defined structures to gain higher aspect ratio or thinner structures than possible with photo lithography. | |||
Revision as of 08:46, 4 November 2013
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 ~170nm/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 | SU8iso etch |
|---|---|---|
| O2 (sccm) | 99 | 99 |
| SF6 (sccm) | 17 | 14 |
| Pressure (mTorr) | 40 | 20 |
| Coil power (W) | 800 | 800 |
| Platen power (W) | 30 | 0 |
| Temperature (oC) | 30 | 10 |
| Etch rate (nm/min) | ~400 | ~170 |
| anisotropy | ~0.8 | ~0.3 |
| Sb in surface layer (%) | <2 | <2.75 |
SU8iso
The SU8iso etch was developed for thinning of lithography defined structures to gain higher aspect ratio or thinner structures than possible with photo lithography.