Noah,

did you also try an area dispense instead of a standard dynamic dispense.
Because of the high viscosities of the BCB's it is sometimes difficult to
get a fully coverage or a good uniformity with no edge bead, especially on
structured wafers.
We coated structured wafers with two Coating methods (Spin and Spray
Coating) and we could avoid coating defects.

I will send our Application note about these BCB Coating tests directly to
you.

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Bernhard Wieder

EV Group Inc. -  Technology Manager  -  Phone: 602 437 9492,  FAX: 602 437
9435,  e-Mail: [email protected],  Internet: www.EVGroup.com
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-----Original Message-----
From: Noah Clay [mailto:[email protected]]
Sent: Monday, April 29, 2002 4:27 PM
To: [email protected]
Cc: [email protected]
Subject: [mems-talk] Spinning BCB on Nitride.


I'm having difficulty spinning BCB on nitride.  There appears to be a
consistent starburst or comet pattern on the wafer despite following the
manufacturer's instructions for dispensing the adhesion promoter and BCB
itself.  I'm using an eppendorf and dispensing until the wafer is
covered in the slow spin stage at 100RPM (I've tried not coating the
wafer completely, but the problem seems exacerbated in those instances).
I'm also dispensing at a level very close to the wafer and very
well-centered.  I've read that the comet pattern usually arises from air
bubbles in the BCB, but I've taken pains to allow settling prior to
dispense.  HELP!

Noah Clay
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