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Au-Sn peel off

2006

We have e-beam deposited Au-Sn (80-20) on the back of the wafer and we are mounting it on an adhesive tape for sawing. But this tape (which is least adhesive available in the market), is peeling off the Au-Sn layer. Is it possible to eliminate this problem by sintering, heating, etc? I appreciate your reply.

Regards,
Deepa

Deepasree Konduparthi
Semiconductor electronics - Westford, Massachusetts

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You could use a coating of wax on the backside before using adhesive tape, after dicing and removal of tape you can dissolve the wax.

What is your substrate? Are you depositing Au/Sn on top of any adhesion layer (say Cr/Au)? Au/Sn will not adhere if you deposit directly without a seed layer.

Annealing (@ 200 - 250'C for several hours ) might help reduce the stress in e-beam deposited Au/Sn (280'c is the melting point). Stress can cause the film to peel, it depends on the thickness, your deposition parameters, etc.

Without more information, it is difficult to give the right fix.

Good luck ..

Karthik Thambidurai
- Austin, Texas
2006