INFICON XTC/3 Thin Film Deposition Controller Operating Manual - Manual (Page 77)

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XTC/3 Operating Manual
3.6.10 RateWatcher
It is easy to automatically sample the deposition rate periodically and then
maintain the proper source power level necessary to keep the rate at the set point
for extended periods of time. With inherently stable deposition sources such as the
planar magnetron, an occasional check of the rate (with the associated automatic
recomputation of the necessary power level) is all that is needed.
This sample and hold type of control can supersede the fully active type of
rate control that normally limits utility of the crystal monitor for in-line or
load-locked systems.
The RateWatcher feature requires entry of two parameters in the Deposit
sub-screen of the Film Parameter display. First, the process engineer must decide
on the RW Accuracy percent (see
RW ACCURACY 1 to 99% on page 4-8 ). This
parameter sets the accuracy that must be maintained for at least five seconds in
order to leave the Sample state.
NOTE: The minimum accuracy range settings are internally limited to a 0.5 Å/s
difference between the setpoint and the just sampled rate. This avoids
unnecessary power changes.
Second, the RW Hold time must be programmed (see RW HOLD 00:00 to 99:59
min:s on page 4-8 ). This is the length of time between the completion of the last
sample period (or the achievement of rate control) and the initiation of the next
sample period. The process engineer may set the interval up to a maximum of
99:59 mm:ss for automatic operation. If longer intervals or periodic samples are
needed, RW Sampl Init and RW Sampl Inhib inputs are available on the SYSTEM
I/O connector. During the RateWatch Hold period, thickness is accumulated at the
setpoint Rate and power is held at the internally computed Time-Power value.
At the end of the RateWatch Hold period, RateWatch Delay will be displayed for
five seconds before the RateWatch Sample message appears. During the
RateWatch Sample period, the power will be adjusted according to
the control loop parameters.
Entering a HOLD TIME of 00:00 disables the RateWatcher feature.
NOTE: In XTC/3S, the RateWatcher function is disabled if the sensor type is
configured for a multi-position sensor head. Also, RateWatcher cannot be
used with the Dual Head configuration
3.6.11 Hand-held Controller (Option)
A Hand-held Controller is provided as an option. The controller serves as a wired
remote to manually control power, switch crystals and produce a STOP. The
handheld controller is connected to XTC/3 with a coiled cord and attaches with a
modular plug to the front panel of XTC/3. The POWER/STOP switch located at the
top of the controller is asymmetrical to increase awareness of the direction of
power increment and decrement.