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. > >