Hi chun.,

I had the same problem.But bubbles formed more during
pouring Su-8 and spin on.you can use primer (convert
hydrophobic to hydrophillic) to avoid buble formation
during spinning. In my process, the bubbles were not
formed during soft baking.

Bala.


--- Chun-Wei Chang  wrote:

> Dear all,
>       I got bubbles problems in  SU8.
> I fabricated micro structures using SU-8 GM1060.
> And I found that there are many bubbles in the SU8
> layer. These bubbles
> started to form at the beginning of  soft bake and
> can be visually
> observed. Otherwise, I cannot see any bubbles right
> after spin coating
> SU-8. Therefore, I excluded the reason of the air
> bubbles trapped in SU8
> during I pour the PR on silicon wafer.  Is the
> temperture of softbak too
> high? Dose anyone have the same problem? All
> suggestion or comment might
> be helpful. Thanks a lot.
>
> Fabrication Process
>
> 1. Carro's acid and BOE clean silicon wafer
> 2. Dehydration 120C  10min
> 3. Spin coating SU8
> 4. Softbake ramped hot plate 65C 10mins -->  95C
> 60mins --> Room
> temperture  (bubbles began to form at the begining
> of softbake)
> 5. Expose
> 6. PEB
> 7. Develop