Hi Prasanna,

Thanks for the reply. Dimension of my SiC mask is 4mmx500micron. Yes I am
stirring HF bath. I have tried BOE also but the composition of BOE which I
am currently using has very slow etch rate (~50nm/min).

Regards,
Priyesh Dhandharia

On Sun, May 30, 2010 at 1:57 AM, Prasanna Srinivasan wrote:

> 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