Manual Version e1-4.3.0.ae-R3. Page
5.3.5.1 Normal Mode Etching Variables
Number of cycles
Since the e1 Series is primarily a pulsed xenon difluoride etching system, the duration of etching is
controlled by the number of cycles. A cycle consists of the xenon difluoride sublimating to the set
pressure in the expansion chamber, etching for a set amount of time and evacuation of the main
chamber and expansion chamber.
Etch Time
When the valve between the main chamber and expansion chamber is opened the pressure
equilibrates and the etching process begins. The etch time is the time between the opening of the valve
between the expansion chamber and the process chamber and the opening of the valve between the
process chamber and the pump.
XeF
2
Pressure
In order to introduce the proper amount of xenon difluoride into the main chamber a set pressure
charge of xenon difluoride must be delivered to the expansion chamber. Because xenon difluoride has
a vapor pressure of ~4T at room temperature the upper limit for the XeF
2
pressure is approximately 4T.
Due to the slightly elevated temperature inside of the etcher cabinet, you may be able to get
considerably higher XeF
2
pressures, however.
N
2
Pressure
Nitrogen can be added into a recipe to improve selectivity. The pressure obtained in the expansion
chamber likewise controls the amount of nitrogen introduced into the process chamber.
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