On 6/23/05, Brubaker Chad  wrote:
> The best suggestion I can make for the alignment is to do a simple
> masking step on the bare wafer, to put basic alignment keys (you could
> possibly even use the first level mask of the SU-8).  Then, do a shallow
> etch to define the patterns. You will then have alignment keys for the
> second layer.
>

HI,
I tried your suggestion which required that I spin the second layer
before developing the result. I have not yet tried to cast PDMS to
this microchannel and hence not sure if the layer will stick to the
wafer. However, I did notice that i see some patches on the
microchannel, which have the color of smoke. My first thought was that
I have not developed SU-8 enough. But I found that no matter how long
I develop, these pathches exist on the channel and the rest of the
wafer is absolutely free of SU-8. Have you encountered such problems
and if so what is the remedy.

Again, thanks a bunch for the help

Vishwa