Manual Version e1-4.3.0.ae-R3. Page
V3 Keep-open N2 Feature and V3 Keep-open Pressure
This feature is typically used in conjunction with etches that use nitrogen. Enabling this feature by
setting V3 Keep-open N2 Feature to True allows the expansion chamber side nitrogen valve (V3) to
remain open throughout the etch and can reduce cycle times. However, if V3 is kept open at low
nitrogen fill pressures (approximately 3 Torr or below), accurate expansion chamber fills may become
difficult. Therefore, this feature has a threshold value below which it will not be enabled. This threshold
value is set via the V3 Keep-open Pressure setting.
Delay .MPG gen. until etch done
This feature is only related to the systems that have the optional image acquisition system option.
Enabling it allows the video file to be created after the etch finishes to minimize the load on the
computer processor during the etch.
Wait for pre-etch stability
This feature requires the system to test the expansion chamber fill pressures before exposing the
wafers to process gas. The tolerance that the expansion chambers must be filled to is set under the
Pre-etch stability threshold below and the number of cycles in a row that must be within the tolerance
before starting is under the Pre-etch stability # of cycles. It is recommended that this feature be
enabled to ensure maximum run-to-run uniformity. A useful trick is that if you are certain that the pre-
cycles are not necessary during a process run, the Stop button can be pressed during the pre-cycle and
it will then begin the etch.
Pre-etch stability threshold
This is the tolerance that the Wait for pre-etch stability routine must satisfy before proceeding to etch
the wafer.
Pre-etch stability # cycles
If Wait for pre-etch stability is selected, this setting allows the user to set the number of pre-cycles in a
row that must be within tolerance before stability is considered to be achieved.
Max stability cycles
If Wait for pre-etch stability is selected, this setting prevents the stability cycles for exceeding a certain
maximum. The system will not etch the wafer if stability is not achieved. The purpose of this maximum
is to prevent the system from wasting substantial quantities of xenon difluoride in the case that the
system is left unattended for a long period of time after initiating a run.
Intermediate Pump-down Pressure
Allows the user to set the intermediate pressure used for expansion chamber through main chamber
pump-downs during an etch cycle.
Pressure Estimation Delay
Allows the user to set the delay after filling of the expansion chamber before the pressure is measured.
This is done to allow time for the pressure in the expansion chamber to stabilize. This time should be
set to the minimum time (usually a few seconds) that it takes for the expansion chamber pressure to
stabilize so that it does not extend the cycle time.
Pressure Estimation Tau
The pressure overshoot is filtered using an exponentially weighted moving average filter. This
parameter allows the user to set the time constant for that filter. Specifically, it setting it to 10 causes
the overshoot correction to take 10 cycles to bring it to the set point. Setting it to 2 causes the
overshoot to take 2 cycles to bring it to the set point. Smaller numbers mean that the corrections per
each cycle are more extreme than larger numbers so there may be some undershoot.
To Next Page
Loading...