Specific Process Knowledge/Etch/Etching of Silicon Oxide/SiO2 etch using RIE1 or RIE2
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RIE (Reactive Ion Etch) can be used for etching silicon oxide. The etch is anisotropic with vertical or angled sidewalls depending on the process recipe and the masking material and geometry. The SiO2 is etched by flour radicals assisted by ion bombardment.
The substrate:
Most be a wafer of 4" or below or small pieces, not higher than about 2mm.
The silicon can be masked by these materials:
- Photoresist
- E-beam resist
- Silicon
- Silicon Nitride
- Aluminium
- Chromium (ONLY RIE2!)
- Other metals if they cover less than 5% of the wafer area (ONLY RIE2!)
Most used recipe (this recipe is being watched in the in the quality assurance program):
| Recipe: | 1SiO2mre |
|---|---|
| CF4 flow | 14 sccm |
| CHF3 flow | 26 sccm |
| Pressure | 100 mTorr |
| RF-power | 60 W |
| Expected results in RIE1 | Expected results in RIE2 | |
|---|---|---|
| Etch rate in SiO2 | ~20-30 nm/min | ~20-30 nm/min |
| Etch rate in Si3N4 | ? | ? |
| Etch rate in P-Si (when used as mask) | ~30 nm/min | ~30 nm/min |
| Etch rate in Si (when not etching SiO2 at the same time) | Expected <2 nm/min | Expected <2 nm/min |
mre:mask resist