Xenon Difluoride
The Xetch® uses Xenon Difluoride as the etching gas. Xenon difluoride exhibits a high selectivity to silicon versus many materials. Xenon difluoride is also widely available. See our overview of the unique advantages of XeF2 etching.
Xenon Difluoride Advantages
- Selectivity during etching
XeF2 shows very high selectivity vs silicon to the majority of semiconductor materials including photoresist, silicon dioxide, silicon nitride, and aluminum. Typically the selectivity of silicon nitride is better than 100:1 and the selectivity to silicon dioxide is better than 1000:1. - No release stiction
XeF2 etching is a dry process so no drying is needed which avoids the sticking issues that often plague wet release processes. - Delicate structures are safely released
Since XeF2 etching is a dry, room temperature process delicate structures can be released. This is particularly useful for releasing delicate devices, such as micromirrors, that are best released after dicing and wire bonding.
Pricing and Availability
XACTIX maintains and updates a list of suppliers of xenon difluoride.
Physical Properties
| Density | 4.32 |
| MW | 169.290 |
| MP | 130-135°C |
| FP | none |
| Vapor Pressure | 3.9 Torr (room temperature) |
Safety
All XACTIX equipment uses sealed XeF2 cylinders along with software-guided cylinder change procedures so using XeF2 is easy. An additional advantage of XeF2 is that it is a solid at room temperature and pressure which makes safe handling easier than many pressurized etching gases. For further information refer to the Material Safety Data Sheets below.