STS Pegasus 4/Processes/LNF Unswitched Poly
LNF Unswitched Poly is a single-step mixed-gas process intended for shallow silicon and thin film poly- and amorphous silicon etches.
| About this Process | |
|---|---|
 | |
| Process Details | |
| Equipment | STS Pegasus 4 |
| Technology | RIE |
| Material | Silicon |
| Mask Materials | PR, SiO2 |
| Gases Used | SF6, C4F8, O2 |
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