Hi Yuanfang Gao,
  KOH etch is bound to give you 54.74 degree slope, since KOH is anisotropic
etch--<100> etches faster than <111>.
  If you want isotropic etch use HF or HF:NH4F or HF:HNO3:CH3COOH:H20.

  I hope this helps.

  Aditya Bhandare

Yuanfang Gao  wrote:
  Dear all,


I met a problem while I tried to pattern metal electrodes into microchannels
of 15-20 um deep, the width is in the range of 10-70 um.


I used S1813 positive resist for lift-off, the problem is that at the edge
of the channel, I found out a metal line along one side of the channel, i.e.
the photoresist is not covering the edge of the channel, another problem is
that the wire to the channel is easily broken.


I used KOH etching of silicon to create the channels, the profile is not
vertical, has the 54.74 degree slope.


Anyone can help me to solve these two problems? Thanks a lot!

Yuanfang Gao