2 ion assisted deposition, 3 control delay, 4 shutter delay – INFICON XTC/3 Thin Film Deposition Controller Operating Manual User Manual

Page 71: 5 rate ramp trigger of final thickness, 6 transfer sensor

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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