quesiton about thin Au film liftoff on Si substrate

Hello labmembers,

 

I’ve got into troubles lifting off very thin Au film recently. I used PMMA as photoresist, and patterned my sample (Si substrate) with ebeam. A very thin Au layer (5 angstroms) was deposited by Innotec. After liftoff, I found many Au nanoparticles or even clusters redeposited onto the unpatterned substrate. I thick it may be partially caused by the electronegativity between Au and Si. I wonder if there is anyway to prevent this behavior. Any comments and suggestions will be highly appreciated. Thanks for your attention.

 

Thanks,

Yuan