INFICON Cygnus Thin Film Deposition Controller - Manual (Page 77)

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Cygnus Operating Manual
MAX POWER OPTION . . . . . . . . . . 0, 1, 2 (default = 1)
This parameter value determines what action will be taken if the Channel
reaches maximum power and is held at maximum power for 5 seconds.
0 = Continue. Selecting a value of 0 will allow the Channel to continue in its
current state.
1 = Idle Ramp. A value of 1 will cause the Channel to enter the Idle Ramp state.
2 = Stop. A value of 2 will cause the Channel to Stop.
RateWatcher™ Sample and Hold Feature
Four parameters — RateWatcher Option, RateWatcher Averaging Time,
RateWatch Time and RateWatch Accuracy — enable the Sample and Hold feature.
When enabled, this feature periodically samples the deposition rate by
automatically opening the sensor shutter and exposing the sensor to the deposition
source. The power is adjusted so the actual rate is set to the desired rate. The
sensor shutter is then automatically closed and power is held constant at the
adjusted level. A five second time delay for thermal stabilization occurs between
opening the shutter and taking measurements.
The RateWatcher Sample phase uses the measured deposition rate to control the
source power. When the deposition rate meets the requirements of the
RateWatcher Accuracy parameter, the RateWatcher Acceptance Window Time is
started. If the rate falls out of the RateWatcher Accuracy requirement, the
RateWatcher Acceptance Time Interval is reset to zero.
If the deposition rate meets the RateWatcher Accuracy requirement for the duration
of the Acceptance Window Time, the sensor shutter is closed and RateWatcher
enters Hold phase for the Hold Time duration.
Finally, after the Hold Time has elapsed, RateWatcher will enter a 5 second Delay
phase. During the Delay phase, the crystal is exposed to the deposition, but the
accumulated rate and sustained power are that from the previous Hold phase. This
Delay phase allows the crystal to thermally stabilize to the deposition before
re-entering the RateWatcher Sample phase.
The RateWatcher Sample Acceptance Window Time (that is, the length of time that
the rate must be within the accuracy range before going into hold) will be calculated
as follows: