It sounds like you are depositing too fast ( A/sec )

Try reducing the dep rate to 2A/sec and also try holding the
Pre-dep ramps longer to make sure the crucible/source metal is good and hot
before the shutter opens.

The power just before the shutter opens should be just under what the
deposition Power will typically be.

You don't want the source so hot that when you open the shutter , you get a
blast of metal 10-15A/sec.

Hope this helps.

 Regards,
 James Wynn

-----Original Message-----
From: Chongfei Shen [mailto:cfshen@gmail.com]
Sent: Wednesday, July 29, 2009 7:40 PM
To: mems-talk@memsnet.org
Subject: [mems-talk] question about ebeam evaportation of metals

Dear all,

I'm using ebeam evaporation to deposit Ti and Al. Both films have dense
particles observed under microscope. The evporation rates are controlled to
be 4A/s. The wafers were thoroughly cleaned.

What are the reasons that forms the particles? How to solve this problem?

Thank you very much for your suggestions.

cfshen