Jay

Does it look like there is Cr left on what should be bare Si after delamination?
That might be important. Also, how are you measuring thickness of the
deposition? What kind of boat or crucible are you using for the metals in the
hot filament system and how healthy are they? As you can see, I still have more
questions than answers.

Typically, an O2 plasma won't adversely oxidize silicon but it won't make up for
inadequate development during lithography. If the plasma process isn't tuned
properly or there are problems with the resist then it can transfer material
from the resist to the open areas and not provide any substantial gains in
cleaning. Lower power might be better if you're worried about this.

It's not conclusive but the gold underneath the peeled films suggests it's not
your litho process. If everything were fine with your metal layers and a resist
residue were causing delamination then you'd expect Cr coloured underside. I'd
guess off the top of my head that your Au layer is being overheated during
deposition, perhaps due to too high a deposition rate or the source being too
close to the target. The Au might be mixing with the underlying Cr, reducing
it's usefulness as an adhesion layer and giving you some Au colouration on the
underside. This is mere speculation not being able to see the films. I'd have
thought that the temperature required for this would adversely affect the resist
or make it difficult to remove though.

Anyhow, I'd try a slower deposition for Au and it couldn't hurt as someone else
pointed out to put down a thicker Cr adhesion layer.

Good luck,
Rick