it depends on the thickness. But generally speaking, it is very hard to get
a very uniform layer across the wafer.

What we did was to coat the entire wafer and cut out only a small central
area for further use. I know it is a waste but...

On Fri, Jun 10, 2011 at 9:39 AM, Khaled Mohamed Ramadan <
khaled.mohamedramadan@kaust.edu.sa> wrote:

> what thickness are you targeting?
>
> On Fri, Jun 10, 2011 at 5:03 PM, 첸로  >wrote:
>
> >
> > Hello
> >
> > I am using the su-8 spin coating on the silicon wafer. I expect a very
> flat
> > su-8 surface because it determines the photolithography resolution. I
> always
> > failedandthe surface is clearly not flat (there is no bubble) even the
> su-8
> > reflow in the softbake process the bead edge can move to the inner.
> >
> > Does anybody know how to make a flat surfacein the spin
> coatingprocesssuch
> > as the acceleration time and the last sudden accelerate 1000 rpm or
> > something?
> >
> > Any comments will be highly appreciated.
> >
> > Kind Regards