[labnetwork] Black Layer Formation During Au E-Beam Evaporation

[Chandan H B]

Dear LabNetwork Community,

We would like to seek inputs from cleanroom/fab facility managers and
process owners regarding an issue observed during *Au deposition in our
E-Beam Evaporators*.

We have observed the formation of *black/dark layer on the Au charge after
a few melt cycles*. The observation occurs during repeated melting of Au in
a tungsten liner/crucible. We are currently investigating whether this
could be related to *material surface contamination, crucible/liner
condition, outgassing, chamber history, or the Au pre-cleaning/conditioning
procedure*.

We would appreciate your experience on the following:

   - Have you observed *black/dark spots or a black layer forming on Au
   during repeated E-beam melting/evaporation*?
   - What *Au purity and material form* do you use?
   - Do you perform any *cleaning/degreasing of the Au charge before
   loading*? If yes, what procedure?
   - Do you follow a specific *crucible/liner cleaning or replacement
   procedure*?
   - If you have identified a *root cause or corrective action* for a
   similar observation, any details would be highly appreciated.

Our objective is to compare practices across facilities and determine
whether this is a *material-handling, source/liner, chamber-condition, or
process-related phenomenon*.
Any suggestions/inputs are highly appreciated.
Thanks in advance!

Regards,
CHANDAN H B
THIN FILMS ENGINEER
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