Do you have access to either a thermal evaporation or e-beam deposition
system? That would eliminate the possibility of the sputter gas
contamination.

It is also possible that your target has been compromised and you are
depositing more than just Cr. That would explain the backside of the peel.

If the backside of the peel is silver, put it in a Cr etchant and see what
happens. I don't think there is a electrochemical effect between Cr/Au so
you should be able to remove the Cr off the back of the Au, assuming if
that is Cr.

You did not mention Piranha clean of wafers before HF. HF is aggressive to
oxide but will not remove contaminants. I would suggest first a Piranha
clean, and then an HF clean.

Good luck.

Henry

Jiang Zhe @memsnet.org on 04/09/2002 04:55:07 PM

Please respond to [email protected]

Sent by:    [email protected]


To:    [email protected]
cc:
Subject:    Re: [mems-talk] Cr/Au delamination



Dear folks,

Thank you for your warm help. Here are some detailed
 information of the etching:
1. The etching was in room temp, no agitation;
2. I did a 90s 2% HF dip before sputtering;
3. I tried 100ACr/2500AAu and 300Cr/8000A Au also, but
delamination also occured; The stress measuremnts
 shows the deposition thickness is correct;
4. I did type test before immersion into HF, Cr/Au
 layer adhered to Si substrate pretty well; didn't
found pin holes or porous structure from SEM pictures;

Now the only thing is Cr got etched in concentrated
HF. But the observation is the backside of the
delamination layer is silver (Cr color). If the
etching rate of Cr is so fast, why the so thin Cr
layer still left? Tommorrow I'll try to measure the
etch rate of Cr. Thanks again.

Jiang
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