Hi there,

you might try this recipe:

Spin S1818, 3000rpm.
Prebake at 95C for 1 min.
Expose, the time depends on your mask aligner.
Develop,  Shipley MF321, around 45s, make sure the required area is developed
completely.
Bake: 60C for 30min hotplate.
E-beam Evaporate Au/Cr, keep the evaporate rate less than 0.3nm/sec.
Soak in acetone and ultrasonicate to finish the lift-off.


Good luck,

Jianhua



Quoting Le Cao Hoai Nam :

> Dear MEMS reseachers,
>
> I am using S-1818 photoresist for a lift off process of Au/Cr on
> borosilicate glass substrate. The thickness of S-1818 is around 2um. And the
> thickness of Au and Cr is 50nm and 80 nm respectively. After a Cr/Au
> evaporation, I soaked the chip in an acetone container in an ultrasonic
> bath. I noticed that even after 50min of ultrasonication the photoresist
> still remained (the manufacturer recommends 10min of ultrasonication) around
> 50% on the chip. On the other hand, it seems that I didn't have the undercut
> pattern after development. I don't know if this have anything to do with the
> remaining of photoresist. I would appreciate it very much if someone could
> shed light on this problem.