I have been interested to read the ongoing comments regarding metal
adhesion.  At present we are experiencing difficulties in this area.  Our
metallisation consists of TiPdAu (500/2000/2000A) evaporated by e-beam onto
an SiO2 coated substrate. We then etch the silicon in an EDP solution.

Currently we are seeing poor adhesion of the metal after EDP etch although
we have had good results in the past. We have had the pads analysed by Auger
by milling through the pad to the interface.  There is no difference between
well adhered and poorly adhered pads. There is also little oxygen in the Ti
and no carbon at the interface.

Specifically I would be grateful to hear comments on the following questions:

Is there a known problem with this metallisation and EDP.? eg.An
electro-chemical effect.

Is it better, in general, to evaporate Ti at a faster or slower rate.?

Are we likely to get a better bond with Ti to an oxide or nitride surface.?


Martin Geear
Nortel Technology
London Road, Harlow
Essex, CM17 9NA, UK

Phone:  +44 1279 403677
FAX:    +44 1279 402765

e-mail: [email protected]