INFICON XTC/3 Thin Film Deposition Controller Operating Manual - Manual (Page 90)

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XTC/3 Operating Manual
and/or the shutter closes, the crystal frequency will decrease due to cooling.
Because small increases in frequency may normally and unavoidably occur, values
of 1 to 24 are not allowed for the Single and Total Stability parameters to prevent
false triggering of crystal fails.
NOTE: Stability is disabled in Etch mode.
SINGLE . . . . . . . . . . . . . 0 Hz and 25 to 9999 Hz (Values 1 to 24 are not allowed)
This sets the maximum permissible increase in frequency from one measurement
to the next. The default value is 0 Hz which disables the function.
TOTAL . . . . . . . . . . . . . . 0 Hz and 25 to 9999 Hz (Values 1 to 24 are not allowed)
This sets the maximum total permissible increase in frequency accumulated during
the active layer. The default value is 0 Hz which disables the function.
NOTE: After a crystal fails due to exceeding the allowable Hz value, the
Crystal Fail state can be cleared by installing a new crystal or pressing
the TOGL key in the Sensors screen with the cursor on Clear S & Q.
4.2.3.3.3 Quality
Quality selects the permissible rate deviation in percent of the measured rate
relative to the desired rate and how many measurements must be outside the
range before the crystal is declared failed.
PERCENT . . . . . . . . . . . 0 to 99% and > 0.5 Å/sec
This sets the deviation that must be exceeded to cause the COUNTS to increment.
The default value is 0% which disables the function.
COUNTS . . . . . . . . . . . . 0 to 99
This sets the number of measurements that must be outside the allowed Percent
before the crystal is declared failed. If the rate deviation relative to the programmed
rate is greater than the programmed threshold limit, the COUNTS value is
incremented. If the rate deviation is less than the programmed threshold, the
COUNTS value is decremented. COUNTS is not allowed to have negative values.
If COUNTS exceeds the value programmed, XTC/3 will automatically crystal
switch, complete the process on TIME-POWER or STOP the process. The rate
deviation is computed on each individual rate measurement during the deposit
phase, i.e., every 250 ms. Upon entering Deposit, the Quality Count is
delayed by a time equal to four times the Time Constant plus the Dead Time, to
allow for normal control loop stabilization. The Q Count on the Operate screen
will show Delay when in pre-deposit, and during the delay period at the beginning
of Deposit.
The default value is 0, which disables the function.
NOTE: After a crystal fails due to exceeding the COUNTS value, the Crystal Fail
state can be cleared by installing a new crystal or pressing the TOGL key
in the Sensors screen with the cursor on Clear S & Q.