INFICON UHV Bakeable Sensor User Manual
Page 46
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PN
07
4-
15
4N
UHV Bakeable Sensor Operating Manual
Crystal ceases to oscillate
during deposition before it
reaches its “normal” life.
Damaged crystal.
Replace the crystal.
Deposition material on crystal
holder opening is touching the
crystal.
Remove material buildup from
the crystal holder opening, being
careful not to scratch the crystal
seating surface (refer to
Deposition material on crystal
holder opening is partially
masking the crystal.
Short crystal life
Crystal life is highly dependent on process conditions of rate,
power radiated from source, location, material, and residual gas
composition.
Crystal does not oscillate or
oscillates intermittently (both in
vacuum and in air).
Damaged crystal.
Replace the crystal.
Sensor or feedthrough has
electrical short or open, or poor
electrical connections.
Check electrical continuity and
isolation of sensor and
feedthrough (see
Crystal oscillates in vacuum but
stops oscillation after open to air.
Crystal is near the end of its life;
opening to air causes film
oxidation, which increases film
stress.
Replace the crystal.
Excessive moisture
accumulation on the crystal.
Turn off cooling water to sensor
before venting vacuum
chamber.
Flow hot water through the
sensor when the vacuum
chamber is open.
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).
Crystal is not properly seated,
causing poor thermal transfer
from crystal to crystal holder.
Check and clean the crystal
seating surface of the crystal
holder (refer to
).
Thermal transfer from crystal
holder to sensor body is
insufficient for the application.
Install a thin metal washer
between crystal holder and
sensor body to improve thermal
transfer (refer to
).
Table 5-1 Symptom, Cause, Remedy (continued)
SYMPTOM
CAUSE
REMEDY