Try to see
Microelectronic Engineering 57–58 (2001) 781–786
i've tried this and it works great!

Andrea

> You're trying to etch silicon, right? Try the HF:HNO3:CH3COOH system. In
> this, HNO3 oxidizes Si, which is then etched by HF. There are lots of
> papers
> on it but start with Madou.
>
> On Fri, Aug 22, 2008 at 9:11 AM, Moshe  wrote:
>
>> > Hello
>> > When I operate wet etch to thin silicon wafer I get like
>> > scratches on the surface.
>> > I am locking for technique to get smooth surface on the silicon
>> > wafer when I operate thinning by wet etch .
>> > The wafer is without any mask.
>> > Thank You