Specific Process Knowledge/Etch/DRIE-Pegasus/Parameters
Short description of some process parameters on the DRIE-Pegasus
- Hardware
- The inside of the process chamber on the Pegasus may be slightly modified.
- Spacers : The distance to the plasma source may be changed by using different spacers.
- Baffle and funnel: The funnel inside the chamber helps to focus the plasma/ions towards the electrode. They may be taken out but don't expect this option to be part of the parameters that you can change in your experiments.
| Acronym | Funnel | Baffle | Spacer |
|---|---|---|---|
| LF+B100 | Long | with baffle | 100 mm |
| LF-B100 | Long | no baffle | 100 mm |
| SF-B5 | Short | no baffle | 5 mm |
- Platen power
- There is a separate low frequency (LF) RF generator that makes it possible to avoid notching at buried insulator layers. The notation
- Pressure
- In some cases the pressure in a recipe may be so low (the density of gas molecules is too low to sustain a plasma) or high (the density of gas molecules is so high that dissociating them into reactive species induced by the RF field produces a pressure increase that is out of the baratron operating range) that it becomes impossible to ignite the plasma. If so, one can include a plasma strike by briefly adjusting to a pressure where igniting the plasma is possible and then once it is striken, adjusting the pressure to the right setting. Hence, the notation 10 (3@15) mTorr means that the process pressure is 10 mTorr with a 3 second strike at 15 mTorr.
- Ramping (>)
- Most process parameters on the DRIE-Pegasus may be ramped during a process step. The notation 140>90 in a pressure setting indicates that from the initial value of 140 mTorr the pressure is decreased linearly to an end value of 90 mTorr in the process step. The ramp rate (mTorr/min) therefore depends on the duration of the step.