Wet Chemical Etching at UCL Device Processing
We have a variety of acids, alkalis and oxidising agents available for wet etching materials. There is also a temperature controlled bath for etches requiring precise temperature control. Below is a table of common etches for various semiconductors and a rough guide to the etch rates expected.
| Etch Mixture |
Etched Material |
Etch rate (approx) /um per min at 20C |
| HCl (conc) |
InP |
5-15 |
| HCl (conc) |
Surface oxide on GaAs |
Fast |
| HCl (conc) |
InGaAs |
<0.02 |
| HCl:H20 (2:1) |
InP |
8 |
| HCl:H2O (1:1) |
InP |
0.7 |
| HCl:H2O (1:2) |
InP |
0.09 |
| H3PO4:HCl (1:1) |
InP |
2.5 |
| H3PO4:HCl (1:2) |
InP |
4.8 |
| H3PO4:HCl (1:3) |
InP |
6.6 |
| H3PO4:HCl (3:1) |
InP |
0.75 |
| H3PO4:H2O2:H2O (3:4:3) |
GaAs |
6 |
| H2O:NH4OH:H2O2 (20:2:1) |
GaAs |
0.5 |
| HBr:CH3COOH:K2Cr2O7 (1:1:1) |
Most III-V compounds |
2-5 |
| H2O2:NH4OH:H2O (0.7:2:100) |
GaAs |
0.1 |
| H2SO4:H2O2:H20 (1:8:80) |
InGaAs |
0.5 |
| Br:CH3OH (1:100) |
Most III-Vs |
1-10 |
| HCl:H2O2:H2O (80:4:1) |
GaAs |
1 |
UCL Device Processing