Working with KOH: Difference between revisions
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Created page with "KOH belongs to the family of anisotropic Si-etchants based on aqueous alkaline solutions. The anisotropy stems from the different etch rates in different crystal directions. The {111}-planes are almost inert whereas the etch rates of e.g. {100}- and {110}-planes are several orders of magnitude faster. At NBI cleanroom, we use as standard a 28 wt% KOH solution. The etch rate and the selectivity towards a SiO2 mask depends on the temperature. We normally use a temperature..." |
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At NBI cleanroom, we use as standard a 28 wt% KOH solution. The etch rate and the selectivity towards a SiO2 mask depends on the temperature. We normally use a temperature of 80°C but it may reduce it to, e.g., 60 °C or 70°C for a higher-precision timed etch. | At NBI cleanroom, we use as standard a 28 wt% KOH solution. The etch rate and the selectivity towards a SiO2 mask depends on the temperature. We normally use a temperature of 80°C but it may reduce it to, e.g., 60 °C or 70°C for a higher-precision timed etch. | ||
{| class="wikitable" | |||
|- | |||
! Si(110) !! Etch rate (μm/min) | |||
|- | |||
| 60°C || 0.4 | |||
|- | |||
| 70°C || 0.7 | |||
|- | |||
| 80°C || 1.3 | |||
|- | |||
|} | |||
Revision as of 14:49, 9 September 2026
KOH belongs to the family of anisotropic Si-etchants based on aqueous alkaline solutions. The anisotropy stems from the different etch rates in different crystal directions. The {111}-planes are almost inert whereas the etch rates of e.g. {100}- and {110}-planes are several orders of magnitude faster.
At NBI cleanroom, we use as standard a 28 wt% KOH solution. The etch rate and the selectivity towards a SiO2 mask depends on the temperature. We normally use a temperature of 80°C but it may reduce it to, e.g., 60 °C or 70°C for a higher-precision timed etch.
| Si(110) | Etch rate (μm/min) |
|---|---|
| 60°C | 0.4 |
| 70°C | 0.7 |
| 80°C | 1.3 |