[mems-talk] Problems with evaporating Titanium

[Yue Mun Pun, Jeffrey]

Hi,
In my process, I am trying to evaporate Titanium on uncrosslinked SU-8.  The purposes for the Titanium are:
1. To serve as a masking layer to protect the underlying uncrosslinked SU-8 from further i-line UV patterning processes.  Thus, it has to be at least 25nm thick.
2. To serve as an adhesion layer for Gold, which will be e-beam evaporated on the Titanium to a thickness of 200-300nm.

For Titanium as a masking layer, I am attempting to resistively or thermally evaporate the Titanium to a thickness of 30-40nm.  However, this continues to prove to be a challenge?  The evaporator I use is Edwards Auto 306 thermal evaporator.  I use Titanium granules of <2mm size and Titanium is 99.5% pure.

Can anyone advise me how to go about evaporating the Titanium or can I use e-beam evaporation of Titanium on uncrosslinked SU-8 2050.  E-beam evaporation is much easier, in my experience.  However, the only concern is that e-beam might cause undesired crosslinking of the underlying SU-8 2050.

Mr. Jeffrey Mun Pun YUE
Division of Bioengineering
Block E3, #05-18, Nanobioanalytics Lab
9 Engineering Drive 1
National University of Singapore
Singapore 117576
Tel: (65) 65165985, Fax: (65) 68723069
E-mail:  g0500396 at nus.edu.sg