Hi all,

I am a design/process/development engineer in wafer fabrication. I have to make
Au ohmic contact on both sides of a Si <111> wafer (n+ and p+). Additional
requirement is that "gold shall be alloyed to minimum eutectic temperature".
Evaporating (e-beam) Au right on Si surface results in bad adhesion and peeling
off. Do you have any experience if I put adhesion layer (we have capabilities of
evaporating Ti) under Au, how thick should it be not to act as barrier layer for
interdiffusion of Au and Si, so Au-Si eutectic can be formed at next annealing
step? Also, eutectic temperature of Au-2.85% Si is 363oC. What should be the
sintering temperature - I am thinking of 380oC? How long should last the
sintering step? What is the best atmosphere - N2, H2, Forming gas (15%H2 -
85%N2)?

Thanking in advance to all of you that will spent a little from your precious
time to help me I am looking forward to hearing from you soon.

Nick