Hi Priyesh,

The etch rate depends on the relative dimension of your features in the SiC
mask. How big is your exposed area? If the exposed area is too small, it
takes more time for the etchant to remove your oxide by capillary action.
Hope you are stirring your HF bath during this process. Certain oxides also
produce insoluble products when it reacts with concentrated HF which might
impede your etch rate. You may try BOE instead of concentrated HF etchant.

Regards,
Prasanna

On Sat, May 29, 2010 at 8:47 PM, priyesh dhandharia <
priyesh.dhandharia@gmail.com> wrote:

> Hi all,
>
> As a part of my project I have deposited 500 micron SiC film strips on
> Si/SiO2 wafer. SiO2 wafer is 1 micron thick. Now I want to etch SiO2 so
> that
> I can make a bridge. I have tried to etch SiO2 with concentrated HF for 1.5
> hrs but SiO2 layer is still there. Please help me.
>
> Thank You very much,
> Priyesh Dhandharia,
> M.Tech (Materials Science)
> IIT Bombay

--
Thanks & Regards,
Prasanna Srinivasan