Hi, I'm a graduate student working on fabricating nanoscale device.

I am recently trying to deposit cobalt on some materials such as Al2O3, gold and palladium.

Unlike other targets I use, the adhesion of cobalt is very poor even with adhesion layer, Ti.

After deposition of Cobalt(~200nm with Ti 20nm), the film comes off on its own in some areas.

In case of patterning with photolithography, the pattern is wiped out with lift-off.

I checked out that the film seemed to barely adhere on a sample, but it is removed right after acetone rinsing.

Target thickness and deposition rate was 200nm and 2A/s, however, the crystal sensor showed very instable deposition rate. (1~3A/s)

I think this is the cause of this issue... but I'm not sure it is correct.

Has anyone experienced a problem like this?

It would be very helpful if you advise me why the rate fluctuates so much and how to deposit cobalt well.

I hope you have a great day.

Thank you in advance!