[mems-talk] Gold pad bonding problem

[Guillaume Bougrine]

Hello,

I am currently facing a problem with gold pads deposited on a tungsten layer.
My gold pads are deposited by sputtering and patterned by lift off.
When a gold wire contacts the pad, the pad-wire bonding is stronger than the tungsten-pad bonding and then the pad is removed.

On one hand, I read papers where they assume this problem can come from the creation of a thin tungsten oxide layer which avoid a stronger bonding. Then the idea would be to etch tungsten a bit just before depositing gold. Do you think it is right?

On the other, friends of mine faced a similar problem but with Silicon instead of Tungsten. They used a chrome layer in between Gold and Si (SiO2) and it worked. I cannot find any information about this for the moment... So, do you think it could work? (or do you know where I could find information?)

Hope one of you will have an idea or at least will give me his/her opinion.

Thank you,

BOUGRINE Guillaume