INFICON SID-242 Thin Film Deposition Controller - Manual (Page 42)

Chapter 3 SQS-242 Software
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Shutter Delay: It is often desirable to assure stable process control before the substrate
shutter opens. Enabling shutter delay requires that the system reach the programmed
control accuracy, and maintain that accuracy for 5 seconds, before deposition begins. If
the programmed accuracy is not reached, the process halts. If accuracy is reached, the
substrate shutter opens and deposition begins once the accuracy has been maintained
for 5 seconds. The Thickness reading is zeroed at the end of the shutter delay period.
The time out function sets the length of time the system will wait for control before
aborting.
Control Error: If the control loop cannot maintain the desired deposition rate, due to
loss of source material, excess rate ramps, or equipment malfunction, a control error
occurs. The error condition can be ignored, the process stopped (output power to 0%),
or the output power held at the same level as when the error occurred. If hold is
selected, PID control is abandoned, but the process will continue to be monitored for
thickness setpoint. The control error accuracy is the value that must be exceeded for 5
seconds to trigger a control error. Use shutter delay accuracy to assure adequate
process control before entering the deposition phase.
Rate Sampling: Rate sampling can extend the life of crystals. With rate sampling, the
deposition rate is sampled for a period of time, then the sensor shutter is closed. Power
is then held at the same level as the final power setting during the sample period.
Continuous selects no sampling; the sensor shutter remains open during deposition.
Accuracy Based sampling opens and closes the shutter at the rate required to maintain
the desired accuracy during the hold phase. Time Based sampling opens the shutter
for a fixed period of time then closes it for a fixed time.