INFICON Sputtering Sensor - Manual (Page 17)

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Sputtering Crystal Sensor Operating Manual
1.2 Troubleshooting
The most useful tool for diagnosing sensor head problems is the DVM (Digital Volt
Meter). Disconnect the short oscillator cable from the feedthrough and measure the
resistance from the center pin to ground. If the reading is less than 1-2 megohms
the source of the leakage should be found and corrected. Likewise, with the
vacuum system open, check for center conductor continuity, a reading of more than
1
Ω from the feedthrough to the transducer contact indicates a problem. Cleaning
contacts or replacing the in-vacuum cable may be required.
Another useful diagnostic is to continuity-test the sensor head without a crystal.
Install the ceramic retainer (item 5) into the Sputtering Head (item 3) holder without
a crystal (item 6) and place into the Sputtering Head body (refer to
Figure 1-3 on
page 1-4 ). The DVM will measure 1
Ω
or less from the center pin of the feedthrough
to ground. Replacing the in-vacuum cable may be required
Table 1-2 Symptom - Cause - Remedy Chart
SYMPTOM CAUSE REMEDY
Large jumps of thickness
reading during deposition. Mode hopping due to
damaged crystal. Replace the crystal.
Use ModeLock
measurement system.
Crystal is near the end of its
life. Replace the crystal.
Scratches or foreign particles
on the crystal holder seating
surface. Clean or polish the crystal
seating surface on the crystal
holder.
Improper crystal seating. Check and clean the crystal
seating surface.
Small pieces of material fell
on the crystal (for crystal
facing-up situation). Check the crystal surface
and blow it off with clean air.
Small pieces of magnetic
material being attracted by
the sensor magnet and
contacting the crystal. Check the sensor opening
hole and remove any foreign
material.