Laurent,

-optimizing Plasma etch process (Bosch or non-Bosch) silicon features
with tapered profile
can be achieved.

-for enlarging after plasma etch (Bosch process):
      -mixed acids (HNO3/HF...) can be used
      -TMAH/KOH can be used to improve the cavity wall only
      -isotropic plasma etch (SF6)

good luck
Ha-Duong Ngo
At 09:37 05.02.2007, you wrote:

>Hello everybody,
>
>After un DRIE etching (Bosch process), I would like to enlarge the entry of
>the cavities.
>
>I heard about :
>
>- HNO3/HF
>- TMAH
>- KOH
>- different post-bake for photoresist
>
>Has someone already done this ?
>
>If yes, what's the process to follow ?