INFICON IC6 Thin Film Deposition Controller User Manual

Page 292

15 - 22

IC6 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 (XtalSix
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

6. Poor thickness reproducibility a. Variable source flux

distribution

a. Move sensor to a more central
location to reliably sample
evaporant, ensure constant
relative pool height of melt,
avoid tunneling into the melt

b. Sweep, dither, or position
where the electron beam strikes
the melt has been changed
since the last deposition

b. Maintain consistent source
distribution by maintaining
consistent sweep frequencies,
sweep amplitude and electron
beam position settings

c. Material does not adhere to
the crystal

c. Make certain the crystal
surface is clean; avoid touching
crystal with fingers, make use of
an intermediate adhesion layer

d. Cyclic change in rate

d. Make certain source's sweep
frequency is not "beating" with
the IC6's measurement
frequency

Table 15-8 Troubleshooting Transducers/Sensors (continued)

SYMPTOM

CAUSE

REMEDY