Hi
There are many possible reasons (most if which have been discussed before).
I would guess thermal stress due to your baking steps is the most likely
reason. Make sure you ramp the temperature slowly and don't cool too
quickly.
Do you really need the hardbake step? It is rarely necessary and could
make adhesion worse due to the additional stress.
Gareth
Chen Han Lee wrote:
>Hi all,
>
>I am wondering if someone can advise me on how to improve the adhesion
>between su-8 and oxide wafers.
>
>The su-8 film (20um thick) breaks and peels off from the wafer after KOH
>etch.
>
>I did hardbake the su-8 at 150C for 3 minutes after developing.