durusmail: mems-talk: thick photoresist development
thick photoresist development
2004-02-16
Qing Yao
2004-02-16
Isaac Wing Tak Chan
2004-02-16
sappasamy@APPLIEDIMAGE.com
2004-02-16
BobHendu@aol.com
2004-02-17
Gary
2004-02-17
Brubaker Chad
2004-02-17
Kevin
2004-02-18
Brubaker Chad
2004-02-18
Bill Moffat
thick photoresist development
Kevin
2004-02-17
  Hi,
  Does anyone have experience using AZ P4903?
  It suppose give you thicker layer because it viscoisty is higher.
  How is the performance as thick photoresist?

  Kevin Tsao

  ----- Original Message -----
  From: "Brubaker Chad" 
  To: "General MEMS discussion" 
  Cc: "Brubaker Chad" 
  Sent: Tuesday, February 17, 2004 1:07 PM
  Subject: RE: [mems-talk] thick photoresist development


  > Qing,
  >
  > I see two possible issues with the method you are using.
  >
  > First, I can almost guarantee you are performing an insufficient
softbake.  The idea of the short soft-bakes in between coats isn't bad (bear
in mind, for a 10 um thick coat of AZ P4620, you will typically need a bake
in excess of 3 min).  However, you need to bear in mind that a cured layer
of photoresist becomes a heat resistance film, so, as you get thicker, its
important to eventually increase the bake time.  Your best bet would be on
the final coat, when you'll probably want a bake of ~ ten minutes. Even
better would be to try to get the proper film thickness in fewer coats
(AZP4620 should easily be capable of a 20 - 25 um coat, if your spinner is
good enough; even >50 is possible).  That way, you are not over-curing (and
making harder to expose/develop) the lower layers.
  >
  > The second issue has to do with the exposure method.  For good sidewall
performance, its necessary to use a collimated light source, which most
flood expose systems are not.  Based on the exposure source, its possible to
create a light angle of several tens of degrees, which directly translates
to sidewall profile.  You'd be better off using a proximity/contact mask
aligner such as an EVG620.
  >
  >
  > Best Regards,
  >
  > Chad Brubaker
  >
  > EV Group       invent * innovate * implement
  > Technology - Tel: (602) 437-9492, Fax: (602)437-9435 e-mail:
C.Brubaker@EVGroup.com, www.EVGroup.com
  >
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  >
  >
  >  -----Original Message-----
  > From: mems-talk-bounces+c.brubaker=evgroup.com@memsnet.org
[mailto:mems-talk-bounces+c.brubaker=evgroup.com@memsnet.org]  On Behalf Of
Qing Yao
  > Sent: Monday, February 16, 2004 10:19 AM
  > To: MEMS-talk
  > Subject: [mems-talk] thick photoresist development
  >
  > Hi,
  >
  > I have difficulty in patterning thick photoresist. The following is what
I did:
  >
  > 1> coat a 4" Si wafer with 5 layers of AZ4620 using a spinner. The
thickness of each layer is about 10 microns and the total thickness of PR is
about 50 microns. Bake the wafer at 110 degree centigrade for 1 min. after
the deposition of each single layer.
  >
  >
  > 2> print the image pattern on a transparency (emulsion down) using a
5080-dpi laser printer. put the transparency mask on top of the PR layer and
put a 4" quartz plate on top of the mask. Then do Fusion Flood exposure. the
dose is about 3300 mJ/cm2. Lots of bubbles are generated during the exposure
process.
  >
  > 3> use 1:4 AZ400K to develop the PR for about 9 minutes.
  >
  > I used both optical microscope and surface profilometer to measure the
side wall. The slope angle is about 50 degrees.
  >
  > However, I need the slope angle to be close to 90 degrees (at least
larger than 80 degrees) so that it is almost perpendicular to the substrate.
What can I do to achieve it? Would you please give me any suggestions?
  >
  > by the way, the thick photoresist layer is sort of mold (for electroless
plating of Ni on Si substrate).
  >
  >
  >
  >
  > Best Regards,
  >
  >
  > Qing Yao
  > ___________________
  > M&IE @ UIUC
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