INFICON XTM/2 Thin Film Deposition Monitor - Manual (Page 111)

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XTM/2 Operating Manual
4. crystal oscillates in
vacuum but stops
oscillation after open to air a. crystal was near the end
of its life; opening to air
causes film oxidation which
increases film stress a. replace crystal
b. excessive moisture
accumulates on the crystal b. turn off cooling water to
sensor prior to venting, flow
warm water through sensor
while chamber is open
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 line to body
(CrystalSix 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