Xenon Difluoride Etching System
Homebuilt system
XeF2 etcher is a system to expose Si samples to XeF2 gas in a cyclic pressure mode in which the etch chamber is repeatedly filled (~2 mbar) and pumped out again. Silicon will etch isotopically. High etch pressure will give a smoother etching surface. The etch rate does not depend on feature size when > 10 micron. Gas reaction; 2 XeF2 + Si => 2Xe(g) + SiF4(g). Samples must be clean, dry and free from oxide. Apply a HF dip, rinse and bake 120 ºC.
The etching is selective
Si : SiO2 => 500 : 1
Si : Si3N4 => 100: 1
Source: Marvell Nanolab
| etch | no etch |
| Mo | Acrylic |
| Nb etches rapidly | Al |
| polySi | AlN |
| Si up to 10 micron/min |
Ga |
| SiGe | Ni |
| Spin-on glass ~50 nm /min |
Pt |
| Ti | photoresist |
| W very rapidly | SiC, ZnO |