Dear All,
I have a doubt. Recently I evaporated 100nm of Aluminium on the back
side (rough side) of a typical n-Si wafer using Edwards E-Beam
Evaporator and I found out that the color of the film had a
slight-golden tinge (instead of being bright-silvery). I know that there
is no contamination in my metal as I use the same source a lot and have
never seen such a result before. The crucible liner is inter-metallic.
Also, when I used another Aluminium source the result was again the same
(ie a golden-tinge). In both the cases, most of the process conditions
were very typical, namely,
Pressure of the chamber = 1-2 E-6 Torr
Max Temperature of the substrate during evaporation = 50'C
Although there was one thing that did happen. In both the above cases,
after I had evaporated 40-50nm of Al, the rate dropped to zero, which
was probably because there might be some cracks in the crucible because
of which Al was flowing out of it and shorting the beam current. Even
after increasing the current a lot, the rate remained at zero and so I
had to stop the evaporation.

Any inputs on the above would be greatly appreciated.

Thanks and regards,
Mantavya


Mantavya Sinha
PhD Student
Dept of ECE
NUS, Singapore