STS Pegasus 4/Processes/LNF Switched Poly
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|About this Process|
|Equipment||STS Pegasus 4|
|Mask Materials||PR, SiO2|
|Gases Used||SF6, C4F8, O2|
LNF Switched Poly is a Bosch-style switched process intended for shallow silicon and thin film poly- and amorphous silicon etches.
The STS Pegasus is not designed for polysilicon etching. There are other tools at the LNF specifically designed for this, including the LAM 9400 and the P5000 RIE. Please make a helpdesk ticket if you need assistance determining the correct tool or recipe for your process.
Follow the standard operating procedure.
|ICP Power||800 W||800 W|
|Bias Power||0 W||20 W|
|Bias Pulsing||N/A||100 Hz 80%|
|Pressure||10 mTorr||10 mTorr|
|C4F8 Flow||150 sccm||120 sccm|
|SF6 Flow||0 sccm||200 sccm|
|Time||1 s||1.65 s|
Etch rate will vary with feature size and loading.
|SPR 220||110 Å/min||8%|
|Silicon dioxide||31 Å/min||18%|
|Silicon nitride||92 Å/min||13%|
|Low stress nitride||80 Å/min||12%|
- Undercut: 80-100 nm
- Sidewall angle: 87-89° (loading dependent)
This recipe exhibits passivation breakthrough at the top corner of the feature (see image at top of page). This appears to go away for large open areas (isolated lines), but if this will be detrimental to your process, please consider another tool for polysilicon etches.
This etch is designed for thin films and shallow etches (< 2 µm). It is not characterized for long processes.
Due to passivation breakthrough at the surface, remaining features narrower than 1 µm will likely be etched away.