Specific Process Knowledge/Etch/DRIE-Pegasus/SOIetch
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SOI
| Recipe | Name | Temp. | Deposition step | Etch step | Comments | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Time | Pres. | C4F8 | SF6 | O2 | Coil | Time | Pres. | C4F8 | SF6 | O2 | Coil | Platen | Showerhead | Runs | Key words | |||
| SOI etch | SOI | 20 | 2 | 25 | 250 | 0 | 0 | 2000 | 3 | 30 | 0 | 400 | 40 | 2800 | 75 (0.025s, 75%) | Old | 1 | |
| SOI | 20 | 2 | 25 | 250 | 0 | 0 | 2000 | 3 | 30 | 0 | 400 | 40 | 2800 | 75 (0.025s, 75%) | New | 1 | OK | |
SOI etch acceptance test
The SOI etch uses the Low frequency (LF) platen generator to minimize the notching at buried stop layers such as the BOX layer in a SOI wafer.
| Parameter | Specification | Average result |
|---|---|---|
| Etch rate (µm/min) | > 10 | 10.7 |
| Etched depth (µm) | 100 | 107 |
| Scallop size (nm) | < 800 | 685 |
| Profile (degs) | 91 +/- 1 | 90.7 |
| Selectivity to AZ photoresist | > 100 | 183 |
| Undercut (µm) | <1.5 | 0.89 |
| Uniformity (%) | < 3.5 | 2.7 |
| Repeatability (%) | <4 | 0.47 |
| Main etch (D->E) | Etch | Dep |
|---|---|---|
| Gas flow (sccm) | SF6 400 O2 40 | C4F8 250 |
| Cycle time (secs) | 3.0 | 2.0 |
| Pressure (mtorr) | 30 | 25 |
| Coil power (W) | 2800 | 2000 |
| LF Platen power (W) | 75 | 0 |
| LF Platen Pulsing software set-up | 0.025s, 75% | - |
| Cycles | 96 (process time 08:00) | |
| Common | Temperature 20 degs, HBC 10 torr, Long funnel, with baffle & 100 mm spacers | |