[mems-talk] KOH etching

[Jeehwan]

Hi,
I didn't see the black color on the etched Si surface. 
Anyhow, if there exists native oxide on Si, it is possible for the etch rate
to be delayed. What you can do is putting your sample into very diluted HF
solution like 100:1 that dose not etch your mask much.
J. Kim 

-----Original Message-----
From: mems-talk-bounces at memsnet.org [mailto:mems-talk-bounces at memsnet.org]
On Behalf Of LSujatha
Sent: Friday, September 01, 2006 9:13 PM
To: mems-talk at memsnet.org
Subject: [mems-talk] KOH etching

Dear friends,
When I am doing KOH etching of Silicon with silicon dioxide mask in 30% 
solution I am getting the black color in the place of silicon to be etched 
and hence the etching starts very late. the etching time becomes almost 
twice.Can anyone tell the reason for this black color formation? How to 
avoid?
Temperature is 75 degrees Centigrade.