INFICON STM-2XM 2-Channel Rate/Thickness Monitor - Manual (Page 126)

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STM-2XM Operating Manual
Thickness reading has large
excursions during source
warm-up or when source shutter
is opened (usually causes
Thickness reading to decrease)
and after the termination of
deposition (usually causes
Thickness reading to increase). Crystal not properly seated or
dirty crystal holder. Check crystal installation.
Clean the crystal seating surface
inside the crystal holder or
replace crystal holder. Refer to
the sensor operating manual.
Excessive heat input to the
crystal. If heat is due to radiation from
the evaporation source, move
sensor farther away (at least
25.4 cm (10 in.)) from source.
Use SPC-1157-G10 crystals
designed to minimize frequency
shifts due to thermal shock.
Inadequate cooling of crystal. Check water flow rate and
temperature for sensor cooling.
Refer to the sensor operating
manual.
Crystal is being heated by
electron flux. Use a sputtering sensor for
non-magnetron sputtering.
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.
Intermittent connection
occurring in sensor or
feedthrough with thermal
variation. Use an ohmmeter to check
electrical continuity / isolation of
sensor head, feedthrough, and
in-vacuum cable. Refer to the
sensor operating manual.
Thickness reproducibility is poor. Erratic evaporation flux
characteristics.
Move sensor to a different
location.
Check the evaporation source
for proper operating conditions.
Ensure relatively constant pool
height and avoid tunneling into
the melt.
Use sensor averaging (refer to
section 3.3.3 on page 3-19 ).
Material does not adhere well to
the crystal. Check for contamination on the
surface of the crystal.
Evaporate an intermediate layer
of appropriate material onto the
crystal to improve adhesion.
Use gold, silver, or alloy crystals,
as appropriate.
Table 6-1 General troubleshooting (continued)
SYMPTOM CAUSE REMEDY