Hi,
I am facing a similar problem with SU-8 2100. The procedure and the
problem is as below :-
1. Spin coat and bake Omnicoat
2. First layer of 2 micron SU-8
Spin coat SU-8 2002
Pre bake : 68 - 2minutes
90 - 5 minutes[ramped to 90 in 10 minutes]
cooled to room temperature
. Exposure : 8 seconds
. Post bake : Same as prebake
. Develop : 2 minutes
3. Second layer of 160 micron SU-8
Pre bake : 68 - 15minutes
90 - 30 minutes[ramped to 90 in 15 minutes]
cooled to room temperature
. Exposure : 2.5 seconds
. Post bake : Same as prebake
. Develop : 20 minutes
PROBLEM :-
While developing second level, some rainbow pattern is seen [an indication
of developer solution going under the crosslinked layers] and then the
structure comes out. When I verified with microscope, the SU-82100
structure came out along with Su-8 2002 layer which is in contact. So
after development of Su-8 2100 layer, SU-8 2002 patterns which are not in
contact with Su-8 2100 were left on the wafer.
Has anyone faced a similar problem ?
Regards
Seena
> Hi,
>
> I'm trying to make some features of about 70 to 80 microns high with
> SU-8 2025. I've used the recipe below. However, after the develop and
> hard bake the photoresist starts to come off the wafer. So it seems it's
> a bonding issue. Can anyone recommend a recipe for 70 micron high
> features with SU-8 2025?
>
> Would a layer of HMDS help the SU-8 bond to the wafer?
>
> Thanks.
>
> ----------
> 1. PhotoResist
> - Spin 8 sec 500 rpm
> - Spread 30 sec 1250 rpm
> - May Need to wipe perimeter of wafer for excess photoresist
>
> 2. Soft Bake
> - 65 deg. C 2 min
> - 95 deg. C 8 min
> - If wrinkles form on cool down try heating up and cooling down again
>
> 3. Exposure
> - 20 sec
>
> 4. PEB
> - 65 deg. C 1.5 min
> - 95 deg. C 6.5 min
>
> 5. Develop
> - Su-8 developer for 6 min
>
> 6. Descum
>
> 7. Hard Bake
> - Heat from 65 deg C to 160 deg C
> - Let sit at 160 deg C for 10 min
> - Cool down to room temp
> ----------------------------------
