Steve,
You may use a diluted concentration. You may try HF:H2O2:DI (1:1:640)
which we usually use in Ti etching.
First, prepare a solution in a small beaker to mix 10 ml of HF, 10 ml of
H2O2, 80 ml of DI water. Then, add 1/4 of this mixture into 1575 ml of
DI water.
Good luck,


Kagan TOPALLI, Ph. D.
Senior Research Engineer
MEMS-VLSI and EMT Group
Middle East Technical University
Dept. of Electrical & Electronics Eng.
TR-06531 Ankara Turkey
Phone: +90 312 210 44 09 or +90 312 210 23 40
Fax: +90 312 210 23 04
http://www.mems.eee.metu.edu.tr/~topalli/
--



Stoffels Steve wrote:
> Hey everybody.
>
> Does anyone have experience etching titanium with SPR-220/7 resist as a
> mask for patterning?  I am using a H20:BHF (9:1) solution to etch
> titanium, however etching a 100nm thick titanium layer gives a undercut
> of 1.3 micron under the resist.  Did anyone else experience this problem
> or have a solution for this?  I tried a postbake in a oven of the resist
> on three different samples 80C 15mins / 80C 25mins / 90C 15mins, this
> did however not change the outcome.
> I also tried to etch in a H2O2 solution, this however takes 2.5 hours to
> etch and after this time the resist started to delaminate.
>
> Any help would be greatly appreciated.
> Greetings,
> Steve Stoffels.
>
>