SIGMA SQC-122c - Manual (Page 48)

Chapter 3 Menus
3-15
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.
Sensor 1: Allows quartz crystal Sensor 1 to be used for the selected film. If both
sensors are assigned to a film, their readings are averaged. If two sensors are
assigned to a film, and one fails, it is excluded from measurements.
Note: If a relay is assigned to Dual Crystal Shutter in the I/O Setup Menu, Sensor 1
becomes the primary sensor and Sensor 2 a secondary sensor. Sensor 1 is used until
a crystal fail condition occurs. When Sensor 1 fails, measurement automatically
switches to Sensor 2. Sensor 2 will be used until the process completes or is aborted.
The next process run will return to Sensor 1.
Film Tooling: Compensates for sensor sensitivity to the selected material. Use Xtal
Tooling in the System Params menu to compensate for each sensor individually.
Output: Selects the control voltage output that is active for the selected layer.
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).
Max Power: The maximum output power allowed for the selected output. The Scale
output voltage is a function of the deposition power supply input specifications, and is
set in the System Parameters menu. Max Power controls the maximum power that can
be used by this process layer.
Slew Rate: The maximum power change allowed on an output, per second. If power or
rate ramps exceed this value, an error will occur.
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: