Try doing a 110 deg post exposure bake instead of a hardbake, or do a 110
deg PEB and a 100 deg hardbake.  Usually a hardbake is not necessary for
plasma etch with S1813.

Robert

-----Original Message-----
From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org]
On Behalf Of Julie Verstraeten
Sent: Friday, July 22, 2005 10:58 AM
To: General MEMS discussion
Subject: [mems-talk] S1813: time and temperature hardbake before Si DRIE

Hi,

I'm currently coating S1813 photoresist on Si sample. The aim is to get
vertical
wall mask for DRIE process on Si (~1.3microns thick).

I have more or less found the exposure time that lead to vertical wall
(almost..). The problem is that the hard bake after development (to
reinforce
resist and so raised up the selectivity in DRIE process), changes the resist
profile in a bad manner (geometry "more round", less vertical wall).

I suppose the hard bake time and temperature are critical. I was using 30min
at
120°C in oven.

Does someone has better advices?

Is it better to use hot plate or oven?

Is postbake really needed before plasma etching?