Migrated from the old Google Sites wiki (Nov 2026). Text and numbers were carried over; photos and screenshots were not. If you have them, add them to assets/wiki/ and link them here. Check numbers against your own run before relying on them.
The tool
The Plasmatherm has two chambers:
- Left (Plasmatherm #1): CVD
- Right (Plasmatherm #2): RIE
It is even simpler to operate than the Oxford 80, and because #2 does not use fluorine-based gases it does not need the large plastic shield.
RIE vs. CVD, in one paragraph
The difference is whether the reaction product is volatile. A volatile product is pumped away and the material is etched (RIE). A nonvolatile product settles on the surface as a film (CVD). The field direction differs too: in RIE it points down, accelerating ions into the surface for anisotropic etching; in CVD it points up, so the reaction happens above the surface and the product falls onto it. Running an etch in the CVD configuration gives a less anisotropic etch.
Operating procedure
- Log in to the tool.
- Click Vent.
- Wait until a large gap opens at the chamber lid; the chamber is then at atmospheric pressure.
- Open the chamber and place your sample on its carrier wafer.
- Close the chamber and hold the lid down while clicking Evacuate. The pump is weaker than on other tools and needs the lid pressed to seal.
- Load your recipe. Yuqi’s recipe YQSIOLPL etches SiO₂ at about 17 nm/min.
Tips
- The tool struggles to reach 30 mTorr. Set process pressure to at least 40 mTorr.
- If your recipe has a purge step (N₂ to displace residual air), the default purge pressure is too low for the tool to reach. Set it to about 212 mTorr.
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