Bake more times?

On Mon, Dec 13, 2010 at 8:49 PM, Xin Yan  wrote:

> Hi everyone,
>
> i want to etch the 7740 about 4 to 20 um deep.  Using Cr with Photoresist
> 5214E  as the mask,  Cr layer was produced by DC sputtering about 200nm
> thick. The etchant is 1 HF : 2 HNO3 : 2 H2O to get high etch rate about
> 2um/min  to the 7740.
>
> we met a problem that  Cr can not stand in this solution even 2minutes.
>  After about 2 min, Cr begin to  peel off.
>
>  In the 49%HF without HNO3, Cr cannot stand even 1minutes.
>
> what cause the Cr so unstable or it is supposed to be like this?  or  i
> need
> to change the etchant ?
>
> Thank you
>
> Yan Xin

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