Xenon Difluoride Etching System
XeF2 etcher is a system to expose Si samples to XeF2 gas in a cyclic mode in which the etch chamber is repeatedly filled (~2 mbar) with XeF2 gas and pumped out again. Silicon will etch isotropically. Higher etching pressure gives a smoother etching surface. The etch rate does not depend on feature size when > 10 micron.
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
|Nb etches rapidly||Al|
|Si up to
~50 nm /min
|W very rapidly||SiC, ZnO|