Thank you Mikael for your advice.

in the former etching i use the Magnetic Stirrers to make the etching process
more uniform. Yesterday , i just put the wafer in the solution without
magnetic stirrer. Cr works fine. it can stand in solution at least 10min.
i 've no idea why become so different between this two circumstances.  for
luck, Cr mask works finally.

On Wed, Dec 15, 2010 at 12:06 AM, Mikael Evander wrote:

> Aha. So what we normally did in our lab was to use the chromium as an
> adhesion layer for the photoresist and use the photoresist as the etch
> mask. That way we etched down to 300 um in pyrex/borofloat and through
> entire 700 um wafers of white crown glass. Might be worth giving it a try.
>
> /Mikael

--
Yan Xin
-Pen-Tung Sah MEMS Research Center,
-Xiamen University, CHINA
XMU HOME:
http://memsc.xmu.edu.cn/mems_renchaiduiwu/XuYuan_Chen-Group/index_1.html