Hi Soumen,
You may want to consider using TMAH for the silicon etching. This
etchant is known to have limited effect on aluminum.

-Mike Pedersen

Soumen Das wrote:

> Hi all
> We are working on fabrication of various MEMS devices.We are facing some
> problem regarding how to protect the aluminium layer while doing the silicon
> etching in KOH solution. Is there any chemical (just like photoresist) which
> can be covered on aluminium layer and also can be patterned so that while
> dipping the silicon wafer in KOH solution the chemical layer will not be
> attacked by KOH solution and it can be used as protecting layer for underneath
> material.
> Any suggestions will be highly appreciated.
> Bye