durusmail: mems-talk: SU8 adhesion problems
SU8 adhesion problems
2014-03-10
Janis Klavins
2014-03-11
Nadim Morhell
2014-03-11
王舒禹
2014-03-11
Sophie Roman
2014-03-11
Bill Moffat
2014-03-11
Janis Klavins
2014-03-12
Parrish Ralston
2014-03-11
João Tiago dos Santos Fernandes
SU8 adhesion problems
Janis Klavins
2014-03-11
Hello everybody,

 Thanks for the answers.

 I will try to answer to all the suggestions and make clear some
other
 things.

 1 Sophie, I want to make LCD's so we cannot change the substrate it

 is a soda-lime glass with ITO on it.
 2. Joao, I am using SU8-100 dissolving it with GBL if neccesary. SU8

 2000 are not possible to use as it uses cyclopentanone as solvent.
 3. Bill, The kiln is not an oven it is a kiln with ten sections of
 hotplate I can set up temperature for each section and how much time
the
 glass is in the kiln It not an oven we use.
 4. Nadim, The layer thickness we want to achieve is 15 microns. I
 dont actually know what thickness we have (it is close to 15
microns).
 Usually I have a two step cooling in the kiln first from 95 to 65
then
 to 45 and then to room temp.

 Increasing the exposure time spoils the patterns we have to expose.

 Another thing I am not coating the SU8 with spin-coater, but we are
 trying to coat it with screen printer. At the moment the layer is
not
 very even. So I have seen sheets where the SU8 is not developing at
all
 where the coating is thinner but is lifting off during development
at
 other parts.

 I will try to change the cooling of the sheet to slower rate and see

 what will happen.

 Another question from me. How much the post exposure bake could
 influence the adhesion to substrate?

 Thanks everyone for the answers,

 Janis

 On 11.03.2014. 17:05, Bill Moffat wrote:
 > Hi Bill
 > His problem is most likely underbaking. SU8 process
recommendations are specific. Hot plate is recommended, not kiln. If
what he means by kiln is an oven, he is probably forming a skin and
trapping solvents and not baking enough to get them out.
 >
 > As far as an adhesion promoter that he probably doesn't need,
APTES or GOPS would do. It's epoxy resist, so either epoxy to meld our
amine to bind....
 > Janis input from Ken Sautter our senior Process Engineer.
Additional thoughts, adhesion to ITO has always been difficult. I
quote Grant Wilson a true resist guru, "we have always had problems
with adhesion to ITO". This has been solved partially by treatment
with OCTS and totally with treatment with vapor OCTS. This is
unfortunately with standard positive resist. It may need APTES or GOPS
for adhesion to SU8. Bill Moffat
 >
 > -----Original Message-----
 > From: mems-talk-bounces+bmoffat=yieldengineering.com@memsnet.org
[mailto:mems-talk-bounces+bmoffat=yieldengineering.com@memsnet.org] On
Behalf Of Janis Klavins
 > Sent: Monday, March 10, 2014 7:51 AM
 > To: General MEMS discussion
 > Subject: [mems-talk] SU8 adhesion problems
 >
 > Hello everybody,
 >
 > I am trying to coat an SU8 material on ITO etched glass. I have a
problem that during development the SU8 lifts off the glass very
easily.
 > if the glass sheet is immersed in the developer the SU8 lifts off
and floats away.
 >
 > I believe that this is a baking problem (too much or not enough)
after coating the SU8. I am using a two step kiln 65 degrees ( 1 min)
and 95 degrees (4 min). The same settings for post exposure bake.
 >
 > Has anyone seen a problem like this?
 >
 > --
 > Best regards,
 > Mr. Janis Klavins
 > EuroLCDs
 > Phone: +37163600300
 > Mobile: +37126141049
 >
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 > Hosted by the MEMS and Nanotechnology Exchange, the country's
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 > Visit us at http://www.mems-exchange.org
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 >
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