Dear all:

  Here are the information I recieved about photoresist spining on
deep trench. Hope they are useful for you too. Thanks all peoples
who give me advice.
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Questions:

Dear all:

I will do some photolithography steps after some corrugations formed
on the wafers. The depth of the corrugations are about 5~7 microns.
The corrugations are formed by this way: Etching silicon by SF6+O2,
namely RIE etching silicon.
However, I found the effect of the photoresist spining was very bad,
even though I slow down the rev to 500 rpm. Could you give some advice
or share some experience with me? Any help will be greatly appreciated.

Thanks in advance,
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Advice:

1. I find that a fast spin speed for a VERY short time, then let the wafer
rest.  A more viscous resist (AZ 4000 series)  may help  with coverage.
Good Luck
Liz

2. One tip I received on helping with this is :

1)  Put wafer on spinner
2)  Flood wafer with resist thinner (for example, AZ 1500)
3)  Put on a lot of resist
4)  Wait about 15 seconds
5)  Spin

Hope this helps.

David Nemeth
Senior Process Engineer
Sophia Wireless, Inc.
14225-C Sullyfield Circle
Chantilly, VA
Ph: (703) 961-9573 x206
Fax:(703) 961-9576

3. Dear Li,

Try contacting an EVG representative in your region. EVG developed a spray
coating system to deal with coating uniformity on topography.

Web site: www.EVGroup.com 
With best regards,

Helge

4. if you want to get thick uniform PR, you can try AZ4620 from Clariant
Corp.
NJ. I did not use it actually. I found it from a paper.

5. Hi Li,
There is a very good reference paper of photoresist coating and
photolithographic technique for topological surface.
You can find the paper from the technical digest of Transducer'01.

J.W. Kwon and E.S. Kim "Microfluidic Channel Routing With Protected Convex
Corners" pp.644-647.

Good luck.

Mark

6. Two papers of Vladimir
"New photoresist coating method for 3-D structured wafers" Sensors &
Actuators,
85 (2000) 377~383.
"Patterning of polyimide and metal in deep trenches" Sensors & Actuators,
A 92, (2001) 208~213.
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Thanks again for you help. I'd like share the information I obtained with
you.

Regards,

Li Gang


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