Hi Lee,

Try SU-8 2005 and SU-8 2050 together or SU-8 5 and
SU-8 50 together. In this way, it should work. Because
SU-8 series and SU-8 2000 series are with different
solvent. Two layers with different solvent will
wrinkle when temperature higher than Tg.

Ren Yang

--- Chen Han Lee  wrote:

> Hi memstalk members,
>
> I hope you guys can help me with this.
> I am trying to make a 2 level su-8 structure.
> the bottom layer is 5um su-8 2005 and top layer is
> 50 um su-8 50.
> after the postbake of the bottom layer, i spin
> deposit the top layer and prebake,
> in the first minute of the 65C stage, the su-8
> starts to wrinkle and  it affect the exposure
> process.
> i have tried developing the bottom layer before
> depositing the top, and it improves a little but
> there are still wrinkles on the surface.
> I have also tried depositing the top layer
> immediately after exposing the bottom layer and
> prebake, so that the postbake of the bottom layer
> and prebake of the top layer is done at the same
> time. But it made it even worse, the su-8 becomes
> puddle-like.