Hi Denis,

>From personnal experience, these bubbles are salts that are formed during
the etching process.

To avoid them, use strong stirring (ultrasonics is even better) during the
etching process and once the etching is done, don't forget to rinse your
wafers in dilute HCl to neutralize and remove those salts.

Edouard Duriau
CS-ABS Imaging engineer
ASML




On Thu, Jan 20, 2011 at 6:05 PM, Denis Petrov wrote:

> Hello,
>
> we are experiencing the following problem.
>
> After a KOH etching of Si the etched surfaces (especially walls) are
> covered
> with small particles (they look like... mmm... bubbles or mushrooms).
> Surface roughness is alright. This is only these "bubbles" that bother.
> Mask is SiO2. Does anybody have any idea what it could be and how to avoid
> them?
>
> Many thanks in advance!
>
> Regards
> --
> Denis