Difference between revisions of "STS Pegasus 4/Processes/LNF Switched Poly"
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Revision as of 14:50, 1 March 2021
| About this Process | |
|---|---|
 | |
| Process Details | |
| Equipment | STS Pegasus 4 |
| Technology | RIE |
| Material | Silicon |
| 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.
Contents
Procedure
Follow the standard operating procedure.
Parameters
| Parameter | Dep | Etch |
|---|---|---|
| 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 |
| Chuck Temperature | 20°C | |
Capabilities
Etch rate
Etch rate will vary with feature size and loading.
| Material | Etch Rate | Uniformity |
|---|---|---|
| Silicon | 0.4 µm/min | ?% |
Mask selectivity
| Material | Etch Rate | Uniformity |
|---|---|---|
| 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% |
Etch profile
- 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.
Limitations
Etch length
This etch is designed for thin films and shallow etches (< 2 µm). It is not characterized for long processes.
Feature size
Due to passivation breakthrough at the surface, remaining features narrower than 1 µm will likely be etched away.
Open area
Unknown
