[labnetwork] Crucible damage in e-beam evaporator

[Savitha P]

Hi,

We use a Leybold univex 400 with EV M-8 ferrotec e-gun assembly for out metal coatings. We have been using an optimized recipe for Al deposition in Cu crucibles for long.

Power % : Raise 1: 10% (V= 10 KV and I ~ 110 mA), 5 mins, hold 2 mins
                Raise 2: 22% (V= 10 KV and I ~ 220 mA), 5 mins, hold 2 mins
                During the deposition Power % goes up to 24% and the current
goes up to 240 mA ( V = 10 KV constant)

Some spit is seen during raise 2.

But recently we got serious concern of Cu crucible melting, mostly towards the gun side. We set the beam as spot pattern (for Ti, beam profile is infinity pattern), but it looks elongated. Beam is centred well.  We set the deposition rate to 0.3 nm/sec. Hearth cooling is done at 20 deg C, with water flow rate at 6 litre per minute. Al source fill in crucible is around 70-80%. Beam ramp down is 5 minutes. Chamber venting is set after 25 minutes.

We used an infinity beam pattern to deposit a thick Al metal coating sometime back. We changed all our settings back to spot pattern again. This issue started after that. Seems, somehow the beam did not come back to previous focus.

We need to know, has anyone came across something like this, and how to overcome this. Any information would be helpful.

Thanks.

Savitha


Dr. Savitha P
Chief Operating Officer
National Nanofabrication Centre
Centre for Nanoscience and Engineering
Indian Institute of Science
Bangalore - 560012
India.
Ph. +91 80 2293 3319
www.cense.iisc.ac.in

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