INFICON SQC-310 Thin Film Deposition Controller - Manual (Page 56)

Chapter 3 Menus
3-18
A description of each film parameter follows:
P Term: The proportional term sets the gain of the control loop. High gains yield more
responsive (but potentially unstable) loops. Try a value of 50, then gradually
increase/decrease the value to respond to step changes in rate setpoint.
I Term: The integral term controls the time constant of the loop response. A small I
term, say .5 to 1 seconds, will smooth the response of most loops.
D Term: The differential term causes the loop to respond quickly to changes. Use 0 or
a very small value to avoid oscillations.
Film Tooling: Compensates for sensor sensitivity to the selected material. Use Xtal
Tooling in the System Params menu to compensate for each sensor individually.
Pocket: Indicates which pocket (1-8) should be used. For this parameter to have an
effect, you must assign the Pocket Relays and Pocket Ready input in System
Parameters I/O setup (see section 3.7).
Crystal Quality: The maximum allowed rate deviation, from the rolling average of the
previous 16 rate readings. Each time the rate deviation exceeds the selected percent
value, a counter is incremented. Each time the deviation is within the selected value,
the counter is decremented (to 0 minimum). If the counter reaches 100 during a
process, the process is aborted. Crystal Quality settings from 0 to 9 indicate:
0 Disabled 5 12.5%
1 30.0% 6 10.0%
2 25.0% 7 7.5%
3 20.0% 8 5.0%
4 15.0% 9 2.5%
Note: The Crystal Quality setting is very sensitive to PID loop tuning. It is best to leave
Crystal Quality disabled until you are confident of your process and PID settings.
Crystal Stability: As material is deposited on the crystal, the frequency normally
decreases. However arcing, mode hopping, or external stresses may cause the crystal
frequency to increase. If the accumulated value of these positive frequency shifts (or a
single large positive shift) exceeds a threshold during a process, a crystal fail condition
is indicated.
0 Disabled 5 200 Hz
1 5000 Hz (1250 Hz single shift) 6 200 Hz (100 Hz single shift)
2 1000 Hz 7 100 Hz
3 500 Hz 8 100 Hz (50 Hz single shift)
4 400 Hz 9 25 Hz