[IMAGE] Hello

I want to develop photoresist to form an angle.
The bottom of the open space(developed part) must be
larger than the upper part of the open space.
In other words, the 'entrance' of developed hole must
be narrower than the bottom side.

like this,

--------- ------------
pr / ` pr
---------------------------
wafer

If there's anybody who knows the way, tell me please.
Thanks.