Dear vikrant,

In my opinion there are two issues you can look at:

If your SiN is thin enough in such a way the etch time is short then you have to
check your step coverage, a thick resist layer will do the job.

However, if your SiN is thick, you will need a long etch time even with a good
step coverage. You may have under etch or/and adhesion problem of the resist to
the surface. In this case you need to solve the adhesion problem as well.

Keep in mind that you may have both issues at the same time...

Regards

> Date: Fri, 6 Aug 2010 08:39:38 +0530
> From: [email protected]
> To: [email protected]
> Subject: [mems-talk] Lithography on Textured Si surface
>
> hello,
>
> We have been trying to pattern SiN deposited on textured Si using
> lithography, but we are unable to obtain desire pattern, as the entire SiN
> gets etched in BHF, the height of the textured surfaces are about 8-10 um.
> Do we need to spin coat a thick layer so that the textured surface is
> covered, or there is there something else?
>
> Do let us know.
>
> vikrant