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XTC/3 Operating Manual
5. thermal instability: large
changes in thickness
reading during source
warm-up (usually causes
thickness reading to
decrease) and after the
termination of deposition
(usually causes thickness
reading to increase)
a. inadequate cooling
water/cooling water
temperature too high
a. check cooling water flow
rate, be certain that cooling
water temperature is less
than 30°C; refer to
appropriate sensor manual
b. excessive heat input to
the crystal
b. if heat is due to radiation
from the evaporation
source, move sensor
further away from source
and use sputtering crystals
for better thermal stability;
install radiation shield
c. crystal not seated
properly in holder
c. clean or polish the crystal
seating surface on the
crystal holder
d. crystal heating caused by
high energy electron flux
(often found in RF
sputtering)
d. use a sputtering
sensor head
e. poor thermal transfer
from water tube to body
(CrystalSix or Crystal12
sensor)
e. use a new water tube
whenever the clamping
assembly has been
removed from the body; if a
new water tube is not
available, use a single layer
of aluminum foil between
the cooling tube and sensor
body, if your process allows
f. poor thermal transfer
(Bakeable)
f. use Al or Au foil washer
between crystal holder and
sensor body
Table 6-2 Troubleshooting transducers/sensors (continued)
SYMPTOM
CAUSE
REMEDY