3 parameter limits, 4 crystal fail – INFICON XTM/2 Thin Film Deposition Monitor User Manual
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XTM/2 Operating Manual
4.3 Parameter Limits
The variable parameters and their limits are listed below. The two thickness
(mass) parameters may be set over a wider range of values through the
computer communications interface. If a value outside the stated limits is
attempted, the message “ERR1” is displayed, see
.
When the “Displayed Units” configuration switches are changed (refer to
) the FINAL THICKNESS and SPT THICKNESS
values are automatically scaled to preserve the settings. If a value rescales out
of limits, “ERR 3” is displayed.
4.4 Crystal Fail
Whenever the ModeLock measurement system is unable to effectively identify
and drive a monitor crystal, a special set of sweep and find instructions are
executed. This sequence takes up to five seconds as it is repeated a number of
times. If the measurement system is unable to recover, the message XTAL FAIL
is displayed and the last "good" rate and thickness values are preserved on the
operate screen until the monitor crystal is replaced or recovers.
Sometimes a monitor crystal will spontaneously recover if its temperature is
reduced or sufficient time passes and the stress induced by the coating is
naturally relieved. Even with the XTAL FAIL message displayed the
measurement system will continue to attempt to find the fundamental resonant
mode’s frequency. This message will disappear when the crystal recovers or is
replaced.
Additional information on crystal failures is presented in
. The ModeLock oscillator is more fully explained in
and
Table 4-2 Parameters and Limits
Parameter
Limits
Units
FILM
1 - 9, 0 in Test Mode
--
DENSITY
0.500 - 99.99
gm/cc
Z-RATIO
0.1 - 9.999
--
TOOLING
10.0 - 500
%
FINAL THICKNESS
0.000 - 999.9*
kÅ/µgm/mgm
SPT THICKNESS
0.000 - 999.9*
kÅ/µgm/mgm
SPT TIMER
00:00 - 99:59
MIN:SEC
*Although the full value range of the parameter may be entered, the
maximum mass loading on a 6 MHz crystal is about 16 mgm.