Hi Jiang,

1. Try doing an HF etch before you put into the chamber. Maybe you have a
layer of oxide on the wafer and the HF is etching through the oxide.
Although sometimes the oxide tends to help adhesion between Cr and Si.
Could you look on the backside of the peel and see what color they are?
That will give you the point of failure.

2. Why so thick of Cr layer? Usually 50Ang to 100Ang will do. If you have a
way of measuring the stress of the films, do a study of stress as a
function of Cr thickness. My experience with Cr typically leads me to
believe that they are high stress, no matter whether you sputter or e-beam.

3. 49% HF does etch Cr under the Au at about 1um per minute (100Ang
Cr/1000Ang Au, e-beamed). If your features are small then this will happen.
Again, check the backside of the peel.

4. Try a tape test before your etch. According to your process, I would
imagine that the failure point for a tape test will be between tape/Au,
i.e. nothing should fail. If any of the layers fail, it is most likely the
source of your problem.

Good luck. Let us know once you find out more.

Henry

Jiang Zhe @memsnet.org on 04/09/2002 08:39:45 AM

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Subject:    [mems-talk] Cr/Au delamination



I have a 300A Cr/2500A Au delamination problem. Cr/Au

was deposited on p-type Si <100> wafer. Then it was
put

into concentrated HF and Cr/Au layer were peeled off

after 30 minutes. The pre-clean (RCA clean and a 2min

Ar plasma pre-etch) was well done before sputtering.

My question is, what's the possible reason of the

delamination? Any suggestion? Thanks!

Jiang
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