Hi,

i'm assuming that you will realize your etch using KOH or TMAH.

As first you should deposit a mask against such echants.
I suggest 100nm of LPCVD silicon nitride.
Then you pattern the silicon nitride realizing your rectangles with the
long side aligned to the (111) plane.
Then you immerse the wafer in the etchant. 40% KOH @ 70-90 deg works well.

This is a general guideline. If you will specify better your problem more
suggestions will surely arise.

Best regards,
Andrea

>  hi,
>
> I need your advice on how to etch a rectangular pattern on <110> silicon
> wafer
>
> tehran polytechnic university
> [email protected]