Common Etch Processes Used in Microfabrication
| Material to be etched | Wet etchants | Plasma etchants |
|---|---|---|
| Aluminium (Al) | 80% phosphoric acid (H3PO4) + 5% acetic acid + 5% nitric acid (HNO3) + 10% water (H2O) at 35–45 °C |
Cl2, CCl4, SiCl4, BCl3 |
| Indium tin oxide (In2O3:SnO2) | Hydrochloric acid (HCl) + nitric acid (HNO3) + water (H2O) (1:0.1:1) at 40 °C | |
| Chromium (Cr) |
|
|
|
Gallium Arsenide (GaAs) |
|
|
| Gold (Au) | Aqua regia | |
| Molybdenum (Mo) | CF4 | |
| Organic residues and photoresist | Piranha etch: sulfuric acid (H2SO4) + hydrogen peroxide (H2O2) | O2 (ashing) |
| Platinum (Pt) | Aqua regia | |
| Silicon (Si) |
|
|
| Silicon dioxide (SiO2) |
|
CF4, SF6, NF3 |
| Silicon nitride (Si3N4) |
|
CF4, SF6, NF3, CHF3 |
| Tantalum (Ta) | CF4 | |
| Titanium (Ti) | Hydrofluoric acid (HF) | BCl3 |
| Titanium nitride (TiN) |
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| Tungsten (W) |
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Read more about this topic: Etching (microfabrication)
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