As Karim says, a very common cause is insufficient exposure dose. Sticking
to the data sheet energy values may not take account of optical energy loss
from your mask and any filters in your system and in my experience much more
energy is often needed. Rapid temperature ramping during bakes (especially
cooling after PEB) is another major cause of delamination.
The bake times giving in the data sheets should be OK but do ramp up from RT
and allow to cool to below 40C before the next steps.

On Tue, Apr 5, 2011 at 22:43, Karim Ogando  wrote:

> Hi,
>
> Su-8 adhesion is highly dependent on the chemical environment of the
> resist. A lot of tips (about adhesion and other issues) can be found
> on memscyclopedia (http://memscyclopedia.org/su8.html).
>
> However, i recommend you to start incrementing the dose of UV
> exposure. As su-8 is a negative epoxy-based resist, the curing process
> is from top to bottom, resulting in poor adhesion if you no expose the
> resist above the critical dose for this thickness.
>
> Best regards,
>
> Karim