INFICON STM-2XM 2-Channel Rate/Thickness Monitor - Manual (Page 124)

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STM-2XM Operating Manual
Crystal fail during deposition
before “normal” life of crystal is
exceeded. Crystal is being hit by small
droplets of molten material from
the evaporation source (spatter
or spitting). Use a shutter to shield the
sensor during source
conditioning.
Move the crystal farther away (at
least 25.4 cm (10 in.)) from the
source.
Damaged crystal or deposited
material is causing stress to
crystal. Replace the crystal.
Use an Alloy crystal if
appropriate for deposited
material.
Material buildup on crystal
holder is partially masking the
crystal surface. Clean or replace the crystal
holder. Refer to the sensor
operating manual.
Shutter is partially obstructing
deposition flux or sensor is
poorly positioned, causing
uneven distribution of material
on crystal. Visually check crystal for an
uneven coating, and if present,
correct shutter or sensor
positioning problem.
Crystal fail when vacuum
chamber is opened to air. Crystal was 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. Avoid condensation by turning
off cooling water to sensor
before opening the vacuum
chamber to air, and then flow
heated water above the dew
point of the room through the
sensor when the chamber is
open.
Table 6-1 General troubleshooting (continued)
SYMPTOM CAUSE REMEDY