INFICON IC/5 Thin Film Deposition Controller User Manual
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IC/5 Operating Manual
CRYSTAL STABILITY ’S’ . . . . . . . . 0 to 9
The Crystal Stability parameter can also be used to effect a crystal fail. In
normal operation, when mass is added to a crystal its frequency of oscillation
will decrease. In the case of the dual sensor, S only affects the primary crystal.
There are, however, a number of reasons, such as thermal shock, high
stresses in the film, electrical arcing from an electron beam gun, or frequency
instabilities, that may cause a positive frequency shift between successive
measurements. The Crystal Stability function is used to monitor these positive
frequency excursions. Values range from 0 to 9. The default value of 0 disables
the function. Values 1 through 9 correspond to the maximum positive frequency
accumulation permitted.
Each time there is a positive shift in frequency, the magnitude of the positive
frequency excursion is accumulated. If the cumulative total, or the maximum
single shift, exceeds the limit set by the Crystal Stability value a crystal fail
function is triggered.
Table 4-4 Crystal Stability Number and Positive Frequency Accumulation
Crystal Stability
Number
Positive Frequency
Accumulation (Hz)
9
25
8
100 (max single shift of 50)
7
100
6
200 (max single shift of 100)
5
200
4
400
3
500
2
1000
1
5000 (max single shift of 1250)
0
Disabled