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XTC/3 Operating Manual
3.6.2 Ion Assisted Deposition
This feature will activate the designated output if the film currently running is in
Deposit
and the
Ion Assist Deposit
parameter in the
Option
sub-screen of
the
Film Parameter
display is set to
Yes
.
3.6.3 Control Delay
When the source shutter opens at the start of deposition, there often is a significant
rate spike due to the sudden heat load arriving at the crystal. Typically, over a
matter of seconds, the crystal equilibrates and becomes stable again. The
Control
Delay
feature suspends action of the control loop on the source control power for
a programmable time interval to prevent the control loop from responding to this
temporary rate spike.
3.6.4 Shutter Delay
This feature ensures that no material is deposited on the substrate until the rate
meets certain requirements. The source shutter relay remains in its normal state
and the sensor shutter relay is active. The sensor, which must be positioned to
sample the source flux with the source shutter closed, provides closed loop rate
control. Rate control must be maintained at ± 5% Å/sec or ± 0.5 Å/sec, whichever
is greater, of the desired deposition rate for five seconds before XTC/3 will enter
the
DEPOSIT
state, opening the source shutter and thus exposing the substrate to
a well controlled rate of evaporant flux. If the required rate control accuracy cannot
be achieved within sixty seconds, the
Delay Failure
alarm message will appear. If
Stop on Alarms
has been set to
Yes
, the layer will
STOP
at the same time.
3.6.5 Rate Ramp Trigger of Final Thickness
To implement this type of film termination, program the
New Rate
value of the rate
ramp to 0.1 Å/sec. When the rate ramp is complete, the film program will proceed
as if a
Final Thickness
limit had been reached.
While a
Rate Ramp
is being processed, the
Rate
parameter's internal value is
continuously updated to match the slope of the
Rate Ramp
.
NOTE:
If the
Time-Power
state is entered, a rate ramp will not be executed; the
film will complete at the programmed
Final Thickness
.
3.6.6 Transfer Sensor
This function provides for the use of a secondary sensor, specified as the
Transfer
Sensor
, to establish rate control in
Shutter Delay
prior to entering
Deposit
, then
transferring back to the film’s sensor upon entering
Deposit
. The function is
selected in the
Option
sub-screen of the
Film Parameter
display.
Delay
option
must be set to
Shutter Delay
or
Both
for the
Transfer Sensor
function to be