Tom,

As a general rule you are correct, the mask size should be 1 inch larger
that the wafer or substrate you are pattering.  This can change
depending on the lithography tool you are using.  Most MEMS devices are
done using 1X contact lithography.  In some technologies reduction
lithography is used and the mask size is determined by the capabilities
of the system used.  This process uses a step and repeat in patterning
the wafer.

Dennis Baird
Photronics




Tom Fan wrote:
>
> Hi all,
>
> Whats the typical correlation between the sizes of photomasks and wafers in
> MEMS fabrication? If I were to fabricate microdevices on 4" wafers, do I need
> 4" or 5" photomasks? I learned from an Internet site that the masks should be
> 1" larger than the wafers to be used. Is this customary or masks of the same
> size as wafers can also be used? Anybody can clarify this issue for me?
>
> Thanks,
> Tom Fan
>
> _______________________________________________
> [email protected] mailing list: to unsubscribe or change your list
> options, visit http://mail.mems-exchange.org/mailman/listinfo/mems-talk
> Hosted by the MEMS Exchange, providers of MEMS processing services.
> Visit us at http://www.memsnet.org/