STS Pegasus 4/Processes/LNF Unswitched Poly
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| About this Process | |
|---|---|
 | |
| Process Details | |
| Equipment | STS Pegasus 4 |
| Technology | RIE |
| Material | Silicon |
| Mask Materials | PR, SiO2 |
| Gases Used | SF6, C4F8, O2 |
LNF Unswitched Poly is a single-step mixed-gas 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.
Contents
Procedure
Follow the standard operating procedure.
Parameters
| Parameter | Units | Setpoint |
|---|---|---|
| ICP Power | W | 500 |
| Bias Power | W | 20 |
| Bias Pulsing | Hz | 40 (80%) |
| Pressure | mTorr | 5 |
| C4F8 Flow | sccm | 50 |
| SF6 Flow | sccm | 100 |
| Ar Flow | sccm | 50 |
| Chuck Temperature | °C | 20 |
Capabilities
Etch rate
Etch rate will vary with feature size and loading.
| Material | Etch Rate | Uniformity |
|---|---|---|
| Silicon | 0.8 µm/min | ?% |
Etch rate is feature size dependent: narrow openings will etch slower than larger open areas.
Mask selectivity
| Material | Etch Rate | Uniformity |
|---|---|---|
| SPR 220 | 250 Å/min | 6% |
| Silicon dioxide | 90 Å/min | 7% |
| Silicon nitride | 220 Å/min | 4% |
| Low stress nitride | 180 Å/min | 4% |
Etch profile
This process etches semi-isotropically. Vertical to lateral etch rate is approximately 2:1.
Limitations
Etch length
This etch is designed for thin films and shallow etches (< 2 µm). It is not characterized for long processes.
Feature size
Remaining features that are narrower than the total depth will be etched away due to undercut during the etch.
Open area
Unknown
